bluuebunny/crossref_metadata_2025 huggingface dataset:
Virus‐inhibiting surgical glove to reduce the risk of infection by enveloped viruses
Authors: Bricout Fernand , Moraillon Anne , Sonntag Philippe , Hoerner Pierre , Blackwelder William , Plotkin Stanley
Published: February 2003

Needle puncture and other accidents that occur during surgery and other procedures may lead to viral infections of medical personnel, notably by hepatitis C (HCV) and human immunodeficiency virus (HIV), now that hepatitis B can be prevented by vaccination. A new surgical glove called G‐VIR, which contains a disinfecting agent for enveloped viruses, has been developed. Herpes simplex type 1 (HSV) was used as a standard enveloped virus in both in vitro and in vivo tests of the virucidal capacity of the glove. Bovine viral diarrhea virus (BVDV) and feline immunodeficiency virus (FIV) were used as models for HCV and HIV, respectively. For in vitro study, a contaminated needle was passed through a glove and residual virus was titrated; for in vivo studies, animals were stuck with a contaminated needle through a glove. Despite variation in virus enumeration inherent in the puncture technique, statistical evaluation showed that infection was reproducibly and substantially reduced by passage through the virucidal layer. For BVDV, the amount of virus passing through the virucidal glove was reduced in 82% of pairwise comparisons with control gloves that lacked the virucidal agent; when plaque counts were adjusted to a common dilution, the median count for the virucidal glove was on the average reduced >10‐fold. In experiments in which the proportion of wells infected with FIV was measured, the ratio of TCID50 values (control glove to G‐VIR) was >15, and probably much higher. For HSV, the amount of virus passing through the virucidal glove was reduced in 81% of comparisons with control gloves; the median of adjusted plaque counts was reduced on the average approximately eightfold or ninefold. In vivo tests with FIV and HSV in cats and mice, respectively, found smaller percentage reductions in infection than the in vitro tests but confirmed the virucidal effect of the gloves. J. Med. Virol. 69:538–545, 2003. © 2003 Wiley‐Liss, Inc.
Human papillomavirus type‐16 variants in Quechua aboriginals from Argentina
Authors: Picconi María Alejandra , Alonio Lidia Virginia , Sichero Laura , Mbayed Viviana , Villa Luisa Lina , Gronda Jorge , Campos Rodolfo , Teyssié Angélica
Published: February 2003

Cervical carcinoma is the leading cause of cancer death in Quechua indians from Jujuy (northwestern Argentina). To determine the prevalence of HPV‐16 variants, 106 HPV‐16 positive cervical samples were studied, including 33 low‐grade squamous intraepithelial lesions (LSIL), 28 high‐grade squamous intraepithelial lesions (HSIL), 9 invasive cervical cancer (ICC), and 36 samples from women with normal colposcopy and cytology. HPV genome variability was examined in the L1 and E6 genes by PCR‐hybridization. In a subset of 20 samples, a LCR fragment was also analyzed by PCR‐sequencing. Most variants belonged to the European branch with subtle differences that depended on the viral gene fragment studied. Only about 10% of the specimens had non‐European variants, including eight Asian‐American, two Asian, and one North‐American‐1. E6 gene analysis revealed that 43% of the samples were identical to HPV‐16 prototype, while 57% corresponded to variants. Interestingly, the majority (87%) of normal smears had HPV‐16 prototype, whereas variants were detected mainly in SIL and ICC. LCR sequencing yielded 80% of variants, including 69% of European, 19% Asian‐American, and 12% Asian. We identified a new variant, the Argentine Quechua‐51 (AQ‐51), similar to B‐14 plus two additional changes: G7842→A and A7837→C; phylogenetic inference allocated it in the Asian‐American branch. The high proportion of European variants may reflect Spanish colonial influence on these native Inca descendants. The predominance of HPV‐16 variants in pathologic samples when compared to normal controls could have implications for the natural history of cervical lesions. J. Med. Virol. 69:546–552, 2003. © 2003 Wiley‐Liss, Inc.
Pathogenicity and antigenicity of a new influenza a (H5N1) virus isolated from duck meat
Authors: Lu X. , Cho D. , Hall H. , Rowe T. , Sung H. , Kim W. , Kang C. , Mo I. , Cox N. , Klimov A. , Katz J.
Published: February 2003

Avian influenza A viruses are the ancestral origin of all human influenza viruses. The outbreak of highly pathogenic (HP) avian H5N1 in Hong Kong in 1997 highlighted the potential of these viruses to infect and cause severe disease in humans. Since 1999, HP H5N1 viruses were isolated several times from domestic poultry in Asia. In 2001, a HP H5N1 virus, A/Duck/Anyang/AVL‐1/2001 (Dk/Anyang), was isolated from imported frozen duck meat in Korea. Because of this novel source of HP H5N1 virus isolation, concerns were raised about the potential for human exposure and infection; we therefore compared the Dk/Anyang virus with HP H5N1 viruses isolated from humans in 1997 in terms of antigenicity and pathogenicity for mammals. At high doses, Dk/Anyang virus caused up to 50% mortality in BALB/c mice, was isolated from the brains and lymphoid organs of mice, and caused lymphopenia. Overall Dk/Anyang virus was substantially less pathogenic for mice than the H5N1 virus isolated from a fatal human case in 1997. Likewise, Dk/Anyang virus was apathogenic for ferrets. Dk/Anyang virus was antigenically distinguishable by hemagglutination‐inhibition (HI) assay from human H5N1 viruses isolated in 1997 and avian H5N1 viruses isolated in 2001 in Hong Kong. Nevertheless, prior infection with Dk/Anyang virus protected mice from death after secondary infection with HP human H5N1 viruses. These results indicate that compared with HP human H5N1 viruses, Dk/Anyang virus is substantially less pathogenic for mammalian species. Nevertheless, the novel source of isolation of this avian H5N1 virus must be considered when evaluating the potential risk to public health. J. Med. Virol. 69:553–559, 2003. © 2003 Wiley‐Liss, Inc.
Immunogenicity and safety of a novel liposomal influenza subunit vaccine (INFLUSOME‐VAC) in young adults
Authors: Ben‐Yehuda Arie , Joseph Aviva , Zeira Evelyne , Even‐Chen Simcha , Louria‐Hayon Igal , Babai Ilan , Zakay‐Rones Zichria , Greenbaum Evgenia , Barenholz Yechezkel , Kedar Eli
Published: February 2003

Influenza and its complications account for substantial morbidity and mortality among young adults and especially among the elderly. In young adults, immunization provides 70–90% protection, while among the elderly the vaccine may be only 30–40% effective; hence the need for new, more immunogenic vaccines. We compared the safety and immunogenicity of a novel IL‐2‐supplemented liposomal influenza vaccine (designated INFLUSOME‐VAC) with that of a commercial subunit vaccine and a commercial split virion vaccine in young adults (mean age 28 years) in the winter of 1999–2000. Seventy‐three healthy young adults were randomly assigned to be vaccinated intramuscularly with the following: a commercial subunit vaccine (n = 17, group A), INFLUSOME‐VAC (n = 36, group B), and a commercial split virion vaccine (n = 20, group C). The three vaccines contained equal amounts of hemagglutinin (∼15 μg each) from the strains A/Sydney (H3N2), A/Beijing (H1N1), and B/Yamanashi. INFLUSOME‐VAC induced higher geometric mean HI titers and higher‐fold increases in HI titers against all three strains, compared with the two commercial vaccines. In addition, seroconversion rates for the A/Sydney and B/Yamanashi strains were significantly higher (P < 0.05) compared with the split virion vaccine, and significantly higher for the three strains compared with the subunit vaccine (69–97% vs 35–65%, P ≤ 0.02). Moreover, the anti‐neuraminidase response was significantly greater (P = 0.05) in group B vs group A. INFLUSOME‐VAC caused mild local pain at the injection site in a significantly higher proportion of the vaccinees (83%). Thus, INFLUSOME‐VAC is an immunogenic and safe vaccine in young adults. J. Med. Virol. 69:560–567, 2003. © 2003 Wiley‐Liss, Inc.
Incidence and characteristics of endemic Norwalk‐like virus‐associated gastroenteritis
Authors: Marshall John A. , Hellard Margaret E. , Sinclair Martha I. , Fairley Christopher K. , Cox Bradley J. , Catton Michael G. , Kelly Heath , Wright Peter J.
Published: February 2003

Endemic gastroenteritis associated with the Norwalk‐like viruses (NLVs) is little understood. This study tested for NLV in gastroenteritis cases in 257 households in Melbourne, Australia, for the period September 1997 to February 1999 by a reverse transcription hemi‐nested polymerase chain reaction. Positive samples were studied by nucleotide sequencing and phylogenetic analysis. NLV was detected in 73 (11.4%) of 638 faecal specimens tested. Twelve (1.9%) were NLV genogroup 1 (G1) and 61 (9.6%) NLV genogroup 2 (G2). Gastroenteritis symptoms associated with NLV G2/no other pathogens were significantly more severe than where no NLV was detected. NLV G1 and NLV G2 were detected in adults and children, males and females. NLV G2 incidence showed a marked seasonal periodicity with significant peaks in the Australian late spring/early summer periods. NLV G1 seasonality was significantly different from that of NLV G2. Seven major NLV clusters were identified by phylogenetic analysis. J. Med. Virol. 69:568–578, 2003. © 2003 Wiley‐Liss, Inc.
Epidemiological features of rotavirus infection among hospitalized children with gastroenteristis in Ho Chi Minh City, Vietnam
Authors: Doan Lan Thi Phuong , Okitsu Shoko , Nishio Osamu , Pham Dung Trung , Nguyen Dung Hoang , Ushijima Hiroshi
Published: February 2003

An epidemiological study of the G serotype and P genotype distribution of group A rotaviruses by using ELISA and/or RT‐PCR was conducted in children (aged 1 month to 15 years) with diarrhea that were admitted to the General Children's Hospital No. 1, Ho Chi Minh City, Vietnam from December 1999 to November 2000. The results showed that rotavirus is associated with 65.6% (889/1355) of diarrheal admissions. Rotavirus infection mostly affected children under 2 years of age with a peak incidence in children 1 to 2 years of age (75.7%) and it occurs year round with a slight seasonal pattern; 99.5% of the specimens could be G‐typed: G1 was predominant (68.7%), followed by G4 (15.4%), G2 (12.3%), G3 (0.6%), and G9 (0.5%). High identities of VP7 nucleotide (96.3 to 96.9%) and deduced amino acid (98.1 to 98.4%) were found between two Vietnamese G9 strains and also the recent emergence of G9 strains US 1205, Brazilian R143, and Malawian MW69. Mixed infections were identified in 17 (2.0%), and 5 strains (0.5%) remained untypable. The four most common worldwide strains, G1P[8], G2P[4], G3P[8], and G4P[8], constituted 81.1% of all rotaviruses typed with G1P[8] being the most prevalent type (58.2%). Unusual G/P combinations (11 strains) were detected in 11.7% of all strains, of which, G1P[4] was the most prevalent, accounting for 5.6% of the total. Several combinations of G and P types were observed in this study, suggesting a complex rotavirus infection pattern in Vietnam. This study has provided for the first time clear indication on the circulating G and P genotypes among hospitalized children in Ho Chi Minh City, Vietnam. The results suggest that these viral infections are prevalent among hospitalized children and that the four most common worldwide G types as well as the four most common G‐P combinations were also infecting children in Ho Chi Minh City, Vietnam. This result could have important implications for rotavirus vaccine programs and for understanding the epidemiological characteristics of human rotavirus in Ho Chi Minh City, Vietnam. J. Med. Virol. 69:588–594, 2003. © 2003 Wiley‐Liss, Inc.
Antibody response after RSV infection in children younger than 1 year of age living in a rural area of Mozambique
Authors: Roca Anna , Quintó Llorenç , Abacassamo Fátima , Loscertales Maria Paz , Gómez‐Olivé Francesc Xavier , Fenwick Fiona , Cane Patricia A. , Saiz Juan Carlos , Toms Geoffrey , Alonso Pedro L.
Published: February 2003

Serological responses have been studied in respiratory syncytial virus (RSV) infected children  < 1 year of age attending the outpatient department of the Manhiça District Hospital (Mozambique). Molecular characterization of viral RNA in nasopharyngeal aspirates from the infected children indicated a high level of genetic uniformity among the infecting viruses, all of which belonged to a single genotype of RSV group A. A representative virus strain, Moz00, was isolated from one of the infants and was used, together with the group A strain A2 and the group B strain 8/60, as antigens in the quantification of infant antibody responses. In this study, 97.5% (39/40) and 96.4% (27/28) of infected children produced an antibody response against Moz00 detected by the membrane fluorescent antibody test (MFAT) and the neutralization test (NT), respectively. Seroconversion rates decreased when the A2 and 8/60 strains were used as antigen in MFAT (95.4% and 88.2%, respectively) or NT (81.8% and 54.5%, respectively), indicating that antibody responses had both group‐ and strain‐specific components. Antibodies in convalescent sera of infected children were compared with maternally derived antibodies detected in a group of children also  < 1 year of age, but with no evidence of RSV infection. The convalescent sera exhibited reduced neutralizing capacity when the 8/60 strain was used as antigen (P = 0.028), suggesting that the infant antibody response lacks neutralizing capacity against strains of the heterologous virus group. Restricted cross‐reactivity and neutralizing capacity of antibodies generated by young children might be expected to induce only moderate protection in subsequent epidemics against genetically distant strains. J. Med. Virol. 69:579–587, 2003. © 2003 Wiley‐Liss, Inc.
Aqueous Gels of Diblock Oxyethylene‐Oxypropylene Copolymers
Authors: Kelarakis Antonis , Havredaki Vassiliki , Booth Colin
Published: February 2003

Aqueous solutions of diblock copolymers E102P37 and E92P55 (E = oxyethylene unit, P = oxypropylene unit) were investigated by rheometry. Storage (G′) and loss (G″) modulus and yield stress (σy) were used to detect and characterise hard and soft gels in experiments which covered the concentration range 4–28 wt.‐% copolymer and the temperature range 5–85 °C. Comparison is made with phase diagrams reported for other diblock copoly(oxyalkylene)s, and it is shown that the mesophase behaviour of these systems depends on the effective thickness of the E‐block corona and the stability of the micelles at low temperatures.

Hard‐gel boundaries (circles) and soft‐gel boundaries (squares) for aqueous solutions of copolymers (○, □) E92P55 and (•, ▪) E96B18.

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Hard‐gel boundaries (circles) and soft‐gel boundaries (squares) for aqueous solutions of copolymers (○, □) E92P55 and (•, ▪) E96B18.
Magnetic Polystyrene Nanoparticles with a High Magnetite Content Obtained by Miniemulsion Processes
Authors: Ramírez Liliana P. , Landfester Katharina
Published: February 2003

The encapsulation of high amounts of magnetite into polystyrene particles can efficiently be achieved by a new three‐step preparation route including two miniemulsion processes. In the first step, a dispersion of oleic acid coated magnetite particles in octane is obtained. In the second step, magnetite aggregates in water are produced in a miniemulsion process by using sodium dodecyl sulfate (SDS) as surfactant. In the third step, the dispersion with the magnetite aggregates which are covered by an oleic acid/SDS bilayer were mixed with a monomer miniemulsion and a second miniemulsion process, an ad‐miniemulsification process, is used to obtain full encapsulation. After polymerization, polymer encapsulated magnetite aggregates were obtained. Characterization by thermogravimetry, preparative ultracentrifugation, and transmission electron microscopy showed that up to 40% magnetite could be encapsulated resulting in particles with a high homogeneity of the magnetite content. Magnetometry measurements reveal that the included iron oxide aggregates still consist of separated superparamagnetic magnetite particles.

Transmission electron micrograph for magnetite polystyrene particles (Latex‐1).

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Transmission electron micrograph for magnetite polystyrene particles (Latex‐1).
ADMET Polymerization as a Route to Functionalized Polycarbosilanes
Authors: Church A. Cameron , Pawlow James H. , Wagener K. B.
Published: February 2003

It is now evident that ADMET chemistry can be employed to prepare a family of unsaturated carbosilane polymers containing a common backbone decorated with different alkoxysilane pendant groups, demonstrating the generality and potential utility of this chemistry. Four functionalized silicon containing dienes have been synthesized by nucleophilic substitution of the same parent diene monomer containing two reactive silicon‐chlorine bonds. These new α,ω‐diene monomers have been polymerized under ADMET conditions using the 2nd generation Grubbs's ruthenium catalyst, producing polymers with useful molecular weights. Variation of the pendant group results in differing chemical and physical properties of the resulting polymers. We believe this chemistry offers much to broaden the synthetic pathways to new organosilicon polymers.

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Synthesis of π‐Conjugated Organometallic Polymer Networks
Authors: Kokil Akshay , Huber Christian , Caseri Walter R. , Weder Christoph
Published: February 2003

The present paper reports the synthesis of π‐conjugated organometallic polymer networks based on poly[2,5‐dioctyloxy‐1,4‐diethynyl‐phenylene‐alt‐2,5,‐bis(2′‐ethylhexyloxy)‐1,4‐phenylene] (EHO‐OPPE), a soluble poly(p‐phenylene ethynylene) (PPE) derivative. The ethynylene moieties of the polymer coordinate to Pt0 centers, which act as conjugated cross‐links. These materials are readily accessible through ligand‐exchange reactions between the linear PPE and Pt(styrene)3. The in‐situ NMR investigation of model reactions of Pt(styrene)3 with diphenylacetylene (DPA) has shown that the ethynylene moieties comprised in the PPE readily coordinate to Pt0 centers under release of the relatively weakly‐bound styrene ligands. Spin‐coating has resulted in cross‐linked films of good optical quality. We also have been able to produce PPE‐Pt‐gels with high solvent content (> 95 wt.‐%). As expected, the coordination of Pt markedly influences the photophysical characteristics of the PPE. The photoluminescence is efficiently quenched, and the absorption maximum in the visible regime experiences a hypsochromic shift.

Ligand‐exchange reaction between EHO‐OPPE and [Pt(PhCHCH2)3] leading to the target EHO‐OPPE‐Pt0 networks.

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Ligand‐exchange reaction between EHO‐OPPE and [Pt(PhCHCH2)3] leading to the target EHO‐OPPE‐Pt0 networks.
Synthesis, Structure and Properties of Melamine‐Based pTHF‐Urethane Supramolecular Compounds
Authors: Öjelund Karin , Loontjens Ton , Steeman Paul , Palmans Anja , Maurer Frans
Published: February 2003

The properties of melamine based supramolecular compounds have been studied with rheological, thermal, mechanical, dielectric and scattering techniques and compared with similar covalently bonded materials. The complexes are based on a linear pTHF‐diol (Mn = 1 000) connected via a diisocyanate with melamine. The results obtained show that, despite of the material's low molecular weight (< 2 000 g · mol−1), it has properties typical for high molar mass polymers. The material has a high modulus above the glass transition temperature, and shows behavior similar to a semi‐crystalline material. This is attributed to the presence of the hydrogen bonds, in combination with phase separation giving rise to hard domain formation. In comparison with a covalently bonded and a low molecular weight material of similar composition, the supramolecular compounds have a higher and more temperature dependent viscosity. By exchanging parts of the pTHF with a low molecular weight diol, in our case hexane diol, the mechanical properties at room temperature could be modified to a stiffer but more brittle material.

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Oligothiophenes for Pattern Formation by Stamping
Authors: Allard Sybille , Braun Lydia , Brehmer Martin , Zentel Rudolf
Published: February 2003

Oligothiophene monomers with a fixed length varying from 3 to 5 thiophene rings were prepared by Stille coupling. They were functionalised with one or two methacrylate groups to allow polymerization and cross‐linking. These monomers can be patterned with the help of soft silicon stamps (e.g., with the micro‐injection moulding in capillaries process) on substrates like glass or flexible polymer foils. If a photoinitiator has been added, they can then be hardened by exposure to UV‐light through the transparent stamp. Afterwards the stamp can be removed. This allows the preparation of several centimeters long oligothiophene lines of a width varying between 50 and 0.5 μm. These lines of semiconducting organic material can be used e.g., as an orientation layer for liquid crystals.

The resulting line patterns from embossing oligomer 17, line width 500 nm.

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The resulting line patterns from embossing oligomer 17, line width 500 nm.
Morphological Evolution of Polyoctenamer upon Photo‐Ageing
Authors: Commereuc Sophie , Svecova Lenka , Verney Vincent
Published: February 2003

The morphological structure evolutions of polyoctenamer upon photo‐ageing have been monitored with the aim of correlating the changes of the microstructure with our previous results concerning chemical and molecular evolutions. The influence of the experimental temperature of photo‐oxidation has been investigated with regard to the melting temperature of the different crystalline microphases. A critical point was clearly exhibited (10 h of UV exposure at 35 °C). Before this point the degradation occurs according an oxidative process and takes place only in the amorphous phases. During this period, the molecular structure changes to induce rapid cross‐linking. After the critical point, the chemical oxidation results from a photolytic process. The extent of the tridimensional network becomes invariant and imperfect crystalline zones are then affected.

Kinetic curves of the formation of carbonylated by‐products (□) and peroxidic species (▪) through photo‐oxidation of V6040 films (thickness about 100 μm) at λ > 300 nm at 35 °C.

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Kinetic curves of the formation of carbonylated by‐products (□) and peroxidic species (▪) through photo‐oxidation of V6040 films (thickness about 100 μm) at λ > 300 nm at 35 °C.
Thermo‐Responsive Organic/Inorganic Hybrid Hydrogels based on Poly(N‐vinylcaprolactam)
Authors: Loos Wouter , Verbrugghe Sam , Goethals Eric J. , Du Prez Filip E. , Bakeeva Irena V. , Zubov Vitali P.
Published: February 2003

A new type of ‘intelligent’ hydrogels has been developed in the form of organic/inorganic hybrid materials by making use of the sol‐gel technology. Poly(N‐vinylcaprolactam) (PVCL) has been incorporated in these materials for its thermo‐responsive properties. The synthesis of the hybrid hydrogels was achieved by the in situ formation of an inorganic silica phase in the presence of an aqueous solution of high molecular weight PVCL. This methodology results in the preparation of micro‐heterogeneous systems in which silica particles of nanometer dimensions act as physical cross‐links for the PVCL molecules. Hydrogen bonds between the remaining non‐condensed silanol groups and the PVCL carbonyl functions, together with physical entanglements, are responsible for the strong interactions between the organic and inorganic phases. Stress‐strain tests on highly swollen materials demonstrated that the unique structure of these thermo‐responsive hybrid hydrogels improves the mechanical stability to a great extent as compared to conventional hydrogels. Transmission measurements demonstrate that the presence of the inorganic phase does not influence the cloud point temperatures of PVCL significantly. On the other hand, the response of the reinforced hybrid hydrogels to temperature becomes less pronounced for increasing silica fractions. The reversibility of the swelling/deswelling process has been demonstrated by swelling experiments as a function of temperature.

PVCL/SiO2 hybrid hydrogels.

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PVCL/SiO2 hybrid hydrogels.
Novel Fluorinated Polymer by Radiation‐Induced Polyaddition of Bisperfluoroisopropenyl Terephthalate with 1,4‐Dioxane
Authors: Enomoto Kazuyuki , Narita Tadashi , Maekawa Yasunari , Yoshida Masaru , Hamana Hiroshi
Published: February 2003

Radical polyaddition of bis(α‐trifluoromethyl‐β,β‐difluorovinyl) terephthalate [CF2C(CF3)OCOC6H4COOC(CF3)CF2] (BFP) with 1,4‐dioxane (DOX) was investigated under γ‐rays radiation from a 60Co source to produce higher molecular weight polymers compared to those yielded by benzoyl peroxide initiation. Prior to polyaddition, the addition reactions of 2‐benzoxypentafluoropropene [CF2C(CF3)OCOC6H5] (BPFP) with tetrahydrofuran (THF) and DOX, and BFP with THF were examined in order to develop probable polyaddition reaction conditions. The polymer bearing 1.5 × 104 as a molecular weight was obtained under the feed molar ratio of DOX/BFP = 16 with an irradiation dose of 2 000 kGy at 40 °C, which is a much higher molecular weight compared to that yielded by benzoyl peroxide.

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Determination of Polyisoprene‐block‐poly(methyl methacrylate) Domain Sizes Using 1H Spin Diffusion
Authors: Werkhoven Thekla M. , Mulder Fokko M. , Zune Catherine , Jérôme Robert , de Groot Huub J. M.
Published: February 2003

The microphase structure of polyisoprene‐block‐poly(methyl methacrylate) diblock copolymers was studied using solid‐state NMR techniques. Wideline separation spectroscopy reveals a narrow interphase between the two polymers. The domain sizes of a lamellar sample and a sample with hexagonally ordered cylinders were determined using 1H spin diffusion. The lamellar sample shows a domain size of 16 ± 2 nm for the minor polyisoprene phase and a long period of 33 ± 4 nm. The cylindrical structure has a long period of 38 ± 7 nm, the diameter of the PMMA cylinders is 21 ± 4 nm. These results are about 20% below the estimates obtained from theoretical calculations according to Helfand and Wasserman.

Morphologies of an a) lamellar, and b) hexagonally ordered cylindrical sample (schematic). The triangle in (b) indicates the symmetry that can be used to calculate the dL.

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Morphologies of an a) lamellar, and b) hexagonally ordered cylindrical sample (schematic). The triangle in (b) indicates the symmetry that can be used to calculate the dL.
SAXS from Four‐Arm Polyelectrolyte Stars in Semi‐Dilute Solutions
Authors: Moinard Delphine , Taton Daniel , Gnanou Yves , Rochas Cyrille , Borsali Redouane
Published: February 2003

We have performed small‐angle X‐ray scattering experiments on semi‐dilute solutions of highly charged star polyelectrolytes. Poly(sodium acrylate) (PANa) and poly(cesium acrylate) (PACs) stars with four arms were successfully synthesized by a combination of atom transfer radical polymerization and chemical modifications. Over a wide range of polyelectrolyte concentration Cp, these two systems as well as their equivalent linear polyelectrolytes were investigated at different ionic strengths. Scattering experiments show the existence of a scattering peak denoted as qmax, which disappears with the addition of a simple electrolyte, evidencing the electrostatic character of the interactions. We have also studied the effect of the charge parameter and the nature of the counterion (Na and Cs) on the scattering properties of these star polyelectrolytes. In the case of PACs, qmax scales with the polyelectrolyte concentration as Cp1/2 over the whole range of studied concentrations, whereas it scales as Cp1/2 (for Cp < 45 mg · ml−1) and Cp1/4 (for Cp > 45 mg · ml−1) in the case of PANa.

Variation of qmax as a function of polyelectrolyte concentration Cp for PA1Cs (○) and PA2Cs (•) stars (error bars are indicated).

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Variation of qmax as a function of polyelectrolyte concentration Cp for PA1Cs (○) and PA2Cs (•) stars (error bars are indicated).
Effect of tert‐Butyl Chloride on the Isoprene Polymerization with Neodymium Isopropoxide/Diisobutylaluminum Hydride and Neodymium Isopropoxide/Methylaluminoxane Catalysts
Authors: Dong Weimin , Endo Kiyoshi , Masuda Toshio
Published: February 2003

The effect of tert‐butyl chloride (tBuCl) as a third catalyst component on the isoprene polymerization with neodymium isopropoxide (Nd(OiPr)3)/diisobutylaluminum hydride (Al(iBu)2H) and Nd(OiPr)3/methylaluminoxane(MAO) catalysts was examined in heptane at a fixed [Al]/[Nd] ratio of 30 and reaction temperatures of 30 and 60 °C. The Nd(OiPr)3/Al(iBu)2H catalyst was inactive without tBuCl, i.e., at [Cl]/[Nd] = 0, while it showed the highest activity under the conditions of [Cl]/[Nd] = 3.0 and an addition order of {Al(iBu)2H + tBuCl} + Nd(OiPr)3 to yield polyisoprene with relatively low molecular weight (Mn ca. 5 × 104), broad MWD (Mw/Mn ca. 5.4), and high cis‐1,4 content (ca. 96%) at 30 °C. On the other hand, the Nd(OiPr)3/MAO catalyst was effective at [Cl]/[Nd] = 0, and the most active at [Cl]/[Nd] = 1.0–1.5 with an addition order of {Nd(OiPr)3 + MAO} + tBuCl to afford polymer with high molecular weight (Mn ca. 8 × 105), fairly narrow MWD (Mw/Mn ca. 1.6) and high cis‐1,4 content (ca. 94%) at 30 °C. Thus, the novel Nd(OiPr)3/MAO/tBuCl system features high activity, high molecular weight, narrow MWD, and high cis‐1,4 stereospecificity, as compared with the conventional Nd(OiPr)3/Al(iBu)2H/tBuCl system.

Effect of the [Cl]/[Nd] mole ratio on the cis‐1,4 contents with Nd(OiPr)3/Al(iBu)2H/tBuCl catalyst. Curve a: at 30 °C, 180 min; curve b: at 60 °C, 90 min.

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Effect of the [Cl]/[Nd] mole ratio on the cis‐1,4 contents with Nd(OiPr)3/Al(iBu)2H/tBuCl catalyst. Curve a: at 30 °C, 180 min; curve b: at 60 °C, 90 min.
Crystallization in ABC Triblock Copolymers with Two Different Crystalline End Blocks: Influence of Confinement on Self‐Nucleation Behavior
Authors: Schmalz Holger , Müller Alejandro J. , Abetz Volker
Published: February 2003

The influence of different confinements active during crystallization within polybutadiene‐block‐polyisoprene‐block‐poly(ethylene oxide) (PB‐b‐PI‐b‐PEO) and the corresponding hydrogenated polyethylene‐block‐poly(ethylene‐alt‐propylene)‐block‐poly(ethylene oxide) (PE‐b‐PEP‐b‐PEO) triblock copolymers on the self‐nucleation behavior of the crystallizable PEO and PE blocks is investigated by means of differential scanning calorimetry (DSC). In triblock copolymers with PEO contents ≤ 20 wt.‐% crystallization of PEO is confined within small isolated microdomains (spheres or cylinders), and PEO crystallization takes place exclusively at high supercoolings. Self‐nucleation experiments reveal an anomalous behavior in comparison to the classical self‐nucleation behavior found in semicrystalline homopolymers. In these systems, domain II (exclusive self‐nucleation domain) vanishes, and self‐nucleation can only take place at lower temperatures in domain IIISA, when annealing is already active. The self‐nucleation behavior of the PE blocks is significantly different compared with that of the PEO blocks. Regardless of the low PE content (10–25 wt.‐%) in the investigated PE‐b‐PEP‐b‐PEO triblock copolymers a classical self‐nucleation behavior is observed, i.e., all three self‐nucleation domains, usually present in crystallizable homopolymers, can be located. This is a direct result of the small segmental interaction parameter of the PEP and PE segments in the melt. As a consequence, crystallization of PE occurs without confinement from a homogeneous mixture of PE and PEP segments.

Self‐nucleation regimes of a block copolymer showing confined crystallization by means of DSC.

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Self‐nucleation regimes of a block copolymer showing confined crystallization by means of DSC.
Dansyl Fluorescence and Local Structure of Dansyl‐Labeled Core‐Shell and Core‐Hair Type Microspheres in Solution
Authors: Horie Kazuyuki , Yamada Sadakazu , Machida Shinjiro , Takahashi Satoshi , Isono Yoko , Kawaguchi Haruma
Published: February 2003

Core‐shell type microspheres with fluorescent dansyl groups at random sites in crosslinked poly(N‐isopropylacrylamide) (PNIPAM) shell chains and core‐hair type microspheres with dansyl groups at terminal sites of PNIPAM hair chains graft‐polymerized with living‐radical mechanism were prepared. Fluorescent spectra indicating the microenvironments of dansyl groups attached to the microspheres and their dependences on temperature and solvent compositions were compared to those of dansyl groups in PNIPAM bulk gels and in free solutions. Fluorescence peak wavelength of dansyl groups in the core‐shell type microspheres showed an extraordinary blue shift in water, suggesting that dansyl groups are incorporated in the semi‐interpenetrating polymer network (SIPN) region of the core‐shell boundary. This is supported by a confocal laser‐scanning fluorescence microscope (CLFM) image of a single particle for the core‐shell type microsphere. Dansyl groups at the chain ends of PNIPAN hairs of the core‐hair type microspheres in water are also located on the surface of hydrophobic cores.

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Hydrogen‐Bonding‐Directed Template Synthesis of Novel Stereo‐Regular Organo‐Bridged Ladder‐Like Polymethylsiloxane
Authors: Tang Huadong , Sun Jin , Zhou Xiaoshu , Fu Pengfei , Xie Ping , Zhang Rongben
Published: February 2003

A novel stereo‐regular organo‐bridged ladder‐like polymethylsiloxane (LPMS) was synthesized by a stepwise coupling polymerization on the basis of an amido H‐bonding‐assisted self‐assembling template. The monomer N,N′‐bis{4‐[3‐(diethoxymethylsilyl)propoxy]‐phenyl}terephthalamide (M), prepared by hydrosilylation reaction at high temperature, was hydrolyzed in a dilute solution at a low temperature to form a ladder‐like supramolecular intermediate through amido H‐bonding interactions, which was further condensed to form the polymer LPMS. A combination of techniques including 1H NMR, 29Si NMR, and FT‐IR spectroscopies X‐ray diffraction (XRD), and differential scanning calorimetry (DSC) were used to characterize the titled polymer LPMS, and the results indicate that the polymer possesses an ordered ladder‐like structure.

29Si NMR spectrum of the polymer LPMS.

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29Si NMR spectrum of the polymer LPMS.
Palladium‐Catalyzed Phosphonation of Polyphenylsulfone
Authors: Jakoby Kai , Peinemann K. V. , Nunes Suzana P.
Published: February 2003

An efficient synthetic procedure for the phosphonation of aromatic polymers was developed and is here exemplified for polyphenylsulfone. This procedure involved the bromination of the polymer and the subsequent bromine‐phosphorus exchange by means of a Pd(0)‐catalyzed PC coupling reaction. In the resulting product, the phosphonate ester pendant groups were attached to aromatic rings of the polymer chain without alkylene spacer units. A substitution degree of almost one phosphonate moiety per repeating unit of the polymer was achieved in the presence of Pd2(dba)3 · CHCl3 as catalyst at 120 °C. Polymers with free phosphonic acid groups were prepared by ester hydrolysis.

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On the Lamellar Crystal Structure of Nylons 6,8 and 8,10: A Study Combining Electron Microscopy and Energy Analysis
Authors: Bermúdez Marta , León Salvador , Alemán Carlos , Muñoz‐Guerra Sebastián
Published: February 2003

Lamellar crystals of nylon 6,8 and nylon 8,10 with chains in a fully extended conformation were obtained by crystallization in solution, and examined by electron and X‐ray diffraction. The same crystal structure appeared to be shared by both nylons crystallized in glycerin. This structure consisted of a mixture of α‐ and β‐forms with features similar to that previously described for lamellar crystals of nylon 4,6 grown in the same solvent. Crystallization of nylon 8,10 in hexane‐2,5‐diol afforded lamellar crystals with sheets stacked in the β‐form. A comparative energy evaluation of the different models that are feasible for the crystal structure of these nylons with fully extended chains indicated very small energy differences among them. The presence of different chain arrangements in the same lamellar crystal, as well as the crystallization of the same nylon in different crystal forms upon slight modification of the crystallization conditions, are fully consistent, therefore, with the results obtained in the energy analysis.

Nylon 8,10 crystals grown in hexane‐2,5‐diol at 150 °C. Inset: The respective electron diffraction patterns.

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Nylon 8,10 crystals grown in hexane‐2,5‐diol at 150 °C. Inset: The respective electron diffraction patterns.
Formation of Regular Hole Pattern in Polymer Films
Authors: Peng Juan , Han Yanchun , Fu Jun , Yang Yuming , Li Binyao
Published: February 2003

Ordered macroporous materials recently have attracted much attention. A method that utilizes the condensation of monodisperse water droplets on a polymer solution is proposed for the preparation of honeycomb microporous films. Our results show that it is a general method that can be used for patterning a wide range of polymers. The presence of water vapor and polymer is necessary for the formation of regular holes in films. The formation of hexagonal packing instead of other kinds of packing takes place because the hexagonal packing has the lowest free energy. The formation mechanisms of regular hole pattern and imperfections in the hexagonal packing are proposed.

Hexagonal hole structures in a PMMA film.

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Hexagonal hole structures in a PMMA film.
Model ω‐Functionalized Linear Polystyrenes with One, Two, and Three Sulfobetaine End Groups: Synthesis, Characterization, and Association Behavior
Authors: Sakellariou Giorgos , Pispas Stergios , Hadjichristidis Nikos
Published: February 2003

Three series of ω‐functionalized polystyrenes (PS) with different molecular weights, the first consisting of dimethylamino end‐capped PSs and the other two of ω‐branched PSs end‐capped with two and three low‐molecular‐weight (Mn ∼ 500 g · mol−1) dimethylamino ω‐functionalized polybutadienes (PB), were synthesized by high‐vacuum anionic polymerization techniques using the functional initiator ([3‐(dimethylaminopropyl)]lithium) and chlorosilane linking chemistry. The ω‐dimethylamino polymers (precursors) were molecularly characterized by size‐exclusion chromatography, low‐angle laser light scattering (LALLS), membrane osmometry, and NMR spectroscopy. The characterization results indicate a high degree of molecular and structural homogeneity. The dimethylamino end groups were transformed to the highly polar sulfozwitterionic ones (see Figure) by reaction with cyclopropanosultone. The mono‐, di‐, and tri‐zwitterion capped polymers were found by LALLS, dynamic light scattering (DLS) and viscometry, to associate in carbon tetrachloride, a good nonpolar solvent for the PS tail. In contrast, results on dimethylamino‐capped precursors show no evidence of aggregation. Aggregation numbers increase in decalin compared with those in carbon tetrachloride. At constant molecular weight of the parental PS, the degree of association increases with increasing number of functional groups and for a given number of functional groups with decreasing molecular weight of the PS tail. Temperature‐dependent light scattering measurements in decalin indicate that aggregation persists at the highest temperature investigated.

A schematic representation of the materials investigated in this study.

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A schematic representation of the materials investigated in this study.
Low‐Temperature Polymerization of Olefins in the Presence of Titanium Monoamidinate/MAO Catalyst
Authors: Liguori Dario , Grisi Fabia , Sessa Irene , Zambelli Adolfo
Published: February 2003

This paper reports the predominantly syndiotactic‐specific polymerization of propylene in the presence of titanium monoamidinate/methylaluminoxane (MAO) catalysts. The same catalysts, depending on the reaction conditions, also promote either predominantly 1,4‐cis or 1,4‐trans polymerization of 1,3‐butadiene and polymerization of styrene either to highly syndiotactic or to stereoirregular polymer. Some preliminary information about the features of propylene polyinsertion is also reported.

Expansion of the 20–24 ppm region of the 13C NMR spectrum of sample 2. The starred resonance at 21.75 ppm and the shoulders are not assigned.

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Expansion of the 20–24 ppm region of the 13C NMR spectrum of sample 2. The starred resonance at 21.75 ppm and the shoulders are not assigned.
Combining ATRP of Methacrylates and ROP of L,L‐Dilactide and ε‐Caprolactone
Authors: Ydens Isabelle , Degée Philippe , Dubois Philippe , Libiszowski Jan , Duda Andrzej , Penczek Stanislaw
Published: February 2003

Coupling atom transfer radical polymerization (ATRP) and coordination‐insertion ring‐opening polymerization (ROP) provided a controlled two‐step access to polymethacrylate‐graft‐polyaliphatic ester graft copolymers. In the first step, copolymerization of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA) was carried out at 80 °C at high MMA concentration by using ethyl 2‐bromoisobutyrate and [NiBr2(PPh3)2] as initiator and catalyst, respectively. Kinetic and molar masses measurements, as well as 1H NMR spectra analysis of the resulting poly(MMA‐co‐HEMA)s highlighted the controlled character of the radical copolymerization, while the determination of the reactivity ratios attested preferential incorporation of HEMA. The second step consisted of the ROP of ε‐caprolactone or L,L‐dilactide, in THF at 80 °C, promoted by tin octoate (Sn(Oct)2) and coinitiated by poly(MMA‐co‐HEMA)s obtained in the first step. Once again, kinetic, molar mass, and 1H NMR data demonstrated that the copolymerization was under control and started on the hydroxyl functions available on the poly(MMA‐co‐HEMA) multifunctional macroinitiator.

Comparison of the SEC traces for the poly(MMA‐co‐HEMA) macroinitiator P2 (line only), the polymethacrylate‐g‐PLA copolymer C2 (line marked by ○), and the polymethacrylate‐g‐PLA C3 (line marked by ▵).

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Comparison of the SEC traces for the poly(MMA‐co‐HEMA) macroinitiator P2 (line only), the polymethacrylate‐g‐PLA copolymer C2 (line marked by ○), and the polymethacrylate‐g‐PLA C3 (line marked by ▵).
Nanoscopic Polymer Particles with a Well‐Defined Surface: Synthesis, Characterization, and Properties
Authors: Ballauff Matthias
Published: February 2003

We review our recent work on polymeric latex particles having a well‐defined surface of grafted polymers. Two types of particles are discussed: i) particles with a thermosensitive shell, and ii) particles bearing a dense layer of linear polyelectrolyte chains on their surface (“spherical polyelectrolyte brush”). Both types of particles consist of a polystyrene core onto which either linear or crosslinked chains are grafted. The synthesis of these core–shell particles proceeds in a two‐step process which is reviewed in detail. In particular, we discuss the photo‐emulsion polymerization used for the synthesis of the spherical polyelectrolyte brushes. Most of the studies of these particles have been done in aqueous suspension. Here the equilibrium structure of the surface layer of the particles has been investigated by dynamic light scattering and by small‐angle X‐ray scattering. Results deduced from the flow behavior of the particles in dilute solution can directly be derived from static data. Very recent data refer to the interaction of the spherical polyelectrolyte brushes with solid interfaces. It is demonstrated that particles bearing positively charged polyelectrolyte chains interact strongly with negatively charged surfaces. The strong interaction that is directly evident from AFM studies can be used to generate 2D networks of the particles on the surface.

Schematic representation of the synthesis of defined spherical polyelectrolyte brushes.

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Schematic representation of the synthesis of defined spherical polyelectrolyte brushes.
Block Copolymers: Past Successes and Future Challenges
Authors: Lodge Timothy P.
Published: February 2003

Block copolymers are the focus of a great deal of research activity in contemporary macromolecular science. This is attributable to a range of fascinating fundamental issues associated with understanding self‐assembly processes in both solution and in bulk, coupled to an adventitious convergence of substantial progress in synthetic versatility, developments in molecular and structural characterization, understanding of the factors that control phase behavior, and elucidation of the response of copolymer materials to external fields. It is argued that due to the rapid progress in these areas block copolymers now stand on the verge of a new generation of sophisticated materials applications, in which particular nanostructures will play a crucial role. This may be contrasted with the current billion dollar annual market for block copolymer materials, in which no substantial advantage is taken of any particular nanostructure. A variety of persistent challenges are identified that stand between block copolymers and widespread success in novel applications; foremost amongst these are issues concerned with processing.
Nuclear Magnetic Resonance Spectroscopy in Macromolecular Science
Authors: Spiess Hans Wolfgang
Published: February 2003

A historical overview of the role of NMR spectroscopy in macromolecular science in general and its coverage in “Macromolecular Chemistry and Physics” in particular is given. In the early days physics‐application to study molecular dynamics, partial alignment of macromolecules and phase separation prevailed, deduced from broad‐line solid‐state NMR. Only somewhat later, high‐resolution NMR in solution was established as an important tool for elucidating the chain microstructure. In the future, these two aspects are expected to merge.

Side group liquid crystalline polymers: 2H NMR has elucidated alignment and dynamics of these complex materials.

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Side group liquid crystalline polymers: 2H NMR has elucidated alignment and dynamics of these complex materials.
Hermann Staudinger Prize 2002
Authors: Mülhaupt Rolf
Published: February 2003

This section contains news of the macromolecular community all over the world. Articles about, for example, people, projects, and market trends are welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E‐mail to macromol@wiley‐vch.de. The editorial office decides which articles will be published.
Computer Simulations for Macromolecular Science
Authors: Kremer Kurt
Published: February 2003

In the context of a few characteristic examples, the perspectives of computational materials science for polymeric systems are being discussed. The examples chosen cover the range from atomistic/quantum models to coarse grained bead spring polymer models.

Cartoon of the average chain conformations near the surface. Since the chains are relatively short and only the chain ends adsorb, there is no entanglement network, which would otherwise enhance the bulk adhesion to the surface. Black lines represent chains with both chain ends stuck to the surface, red lines represent chains with only one chain end stuck to the surface and the other in the bulk, and light blue lines represent chains in the bulk.29

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Cartoon of the average chain conformations near the surface. Since the chains are relatively short and only the chain ends adsorb, there is no entanglement network, which would otherwise enhance the bulk adhesion to the surface. Black lines represent chains with both chain ends stuck to the surface, red lines represent chains with only one chain end stuck to the surface and the other in the bulk, and light blue lines represent chains in the bulk.29