bluuebunny/crossref_metadata_2025 huggingface dataset:
Parents' perspectives on having their children interviewed for research
Authors: Hadley Emily K. , Smith Carrol A.M. , Gallo Agatha M. , Angst Denise B. , Knafl Kathleen A.
Published: December 2007

We describe parents' perspectives on research interviews with their children with single gene conditions. One hundred forty‐two parents were interviewed between 2002 and 2003 in a larger study using a qualitative descriptive design. Two questions from the semi‐structured interview guide were used to identify parents' perspectives about future interviews. Almost all of the parents said they would allow an interview with their children, but some parents specified stipulations. These stipulations included: focusing on age‐appropriate information, limiting information with child, considering input from parents, and providing a child‐oriented environment. Knowing this information, researchers can prepare to work more collaboratively with parents and include them more fully in the research process. © 2007 Wiley Periodicals, Inc. Res Nurs Health 31:4–11, 2008
Development and psychometric evaluation of the instrument: Attitude toward patient advocacy
Authors: Bu Xiaoyan , Wu Yow‐wu B.
Published: December 2007

Nurses' patient advocacy can influence patient outcomes. There is a lack of reliable and valid instruments on patient advocacy. The purpose of this study was to develop an instrument to measure nurses' attitudes toward patient advocacy. Bu and Jezewski's theory of patient advocacy and Fishbein and Ajzen's definition of attitude were used to guide the development and evaluation of the scale. Seven experts evaluated scale content validity. Two samples (N = 200; N = 2,500) were randomly selected from the Oncology Nursing Society membership to allow us to examine psychometric properties of the scale. The scale possessed satisfactory psychometric properties. © 2007 Wiley Periodicals, Inc. Res Nurs Health 31:63–75, 2008
Negotiating the challenges of multidisciplinary responses to sexual assault victims: Sexual assault nurse examiner and victim advocacy programs
Authors: Cole Jennifer , Logan T.K.
Published: December 2007

The purpose of this study was to examine Sexual Assault Nurse Examiner (SANE) programs' relationships with victim advocacy organizations. A national telephone survey was conducted of randomly selected SANE programs, all of which served adults, and some of which also served adolescents and children. Nearly one‐third of 231 participants reported that SANEs in their program had experienced conflicts related to roles and boundaries with victim advocacy organizations at some point during the program's history. The most frequently mentioned conflicts involved professional autonomy, control, or turf issues. Future researchers should address personnel, organizational, and structural factors that facilitate collaborative relationships between SANE and victim advocacy organizations. © 2007 Wiley Periodicals, Inc. Res Nurs Health 31:76–85, 2008
Effectiveness of teaching an early parenting approach within a community‐based support service for adolescent mothers
Authors: Drummond Jane E. , Letourneau Nicole , Neufeld Susan M. , Stewart Miriam , Weir Angela
Published: December 2007

A single blind, pre‐test, post‐test design was used to test the effectiveness of the Keys to Caregiving Program in enhancing adolescent mother–infant interactions. Participants were sequentially allocated to groups in order of referral. The outcome was the enhancement of maternal and infant behaviors that exhibited mutual responsiveness as measured by the Nursing Child Assessment Teaching Scale. Issues with recruitment and collaboration with the community agencies made achieving a desirable sample size difficult. Pre‐tests and post‐tests were completed for 13 participants. While the sample size was insufficient to confidently establish whether or not the Keys to Caregiving produced a between groups treatment effect, mothers within the treatment group evidenced significantly greater contingent responsiveness over time than those within the control group. © 2007 Wiley Periodicals, Inc. Res Nurs Health 31:12–22, 2008
Antibiotic use in five children's hospitals during 2002–2006: the impact of antibiotic guidelines issued by the Chinese Ministry of Health
Authors: Zhang Wenshuang , Shen Xuzhuang , Wang Yi , Chen Yuan , Huang Min , Zeng Qiyi , Wei Jinghai , Lu Quan , Wang Gang , Deng Li , Wang Xiaohong , Yao Kaihu , Yu Sangjie , Yang Yonghong
Published: December 2007

Purpose

To investigate the pattern of antibiotic use in five Chinese children's hospitals from 2002 to 2006. To see if the Guidelines to encourage rational use of antibiotics issued by the Ministry of Health in October 2004 have any impact on the use.

Methods

The Anatomical Therapeutic Chemical Classification/Defined Daily Doses (ATC/DDD) methodology was used. Aggregate data on antibiotic use (ATC code‐J01) were expressed in numbers of DDD/100 bed‐days for inpatients.

Results

Total 56 different substances of systemic antibiotics were used. The overall consumption of antibiotic drugs was 68.2, 58.4, 65.8, 65.6 and 49.9 DDD/100 bed‐days for the years 2002–2006, respectively. The top antibiotics used were third‐generation cephalosporins. There was considerable variation in both type and amount of antibiotics used in the five hospitals. In 2002, some hospitals had twice the antibiotic use compared to others. While the overall antibiotic use in 2005 was largely unchanged compared with previous years, by 2006 antibiotic use had decreased by 22.6% and the variation in use between hospitals was also reduced.

Conclusions

The ATC/DDD methodology proved useful for studying overall antibiotic usage in children's hospitals. The decline in antibiotic usage found in 2006 (and the reduced variation between hospitals) may be attributed to the impact of the Ministry of Health guidelines which took some time to be promulgated to individual staff members. Further research will focus on compliance of antibiotic use in these five hospitals with particular guideline recommendations for specific clinical problems such as bacterial resistance and surgical antibiotic prophylaxis. Copyright © 2007 John Wiley & Sons, Ltd.
Factors influencing the CON bond strength of the alkoxyamines in the styrene–acrylonitrile–TEMPO copolymerization system
Authors: Megiel E. , Kaim A.
Published: December 2007

Homolytic bond dissociation energy (BDE) of the (CON) bond for several N‐alkoxyamines derived from 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and the corresponding (CH) bonds were determined from quantum‐mechanical calculations including the B3‐LYP6‐31G(d), B3‐LYP/6‐311++G(2df,p), UB3‐LYP/6‐311+G(3df,2p), and integrated IMOMO (G3:ROMP2/6‐31G(d)) method. The investigated N‐alkoxyamines were considered as models for dormant forms of propagating chains in the radical copolymerization process of styrene with acrylonitrile in the presence of TEMPO according to the terminal and penultimate model. The substituent effect on BDE was investigated. Radical stabilization energies (RSE) for radicals created from homolysis of the investigated N‐alkoxyamines were calculated according to Rüchardt's method. Polar, steric, and stabilization effects on CON alkoxyamine bond homolysis were studied. A dramatically weakened CON bond in the alkoxyamine‐containing two consecutive styrene units in the propagating chain was ascribed to geometric parameters characterizing energetically unfavorable conformation of the substituents. These phenomena can be regarded as the penultimate effect in the radical living/controlled copolymerization system of styrene with acrylonitrile. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1165–1177, 2008
Surface‐initiated ring‐opening polymerization of p‐dioxanone on Wang resin bead
Authors: Lee Hyo Jin , Ramaraj B. , Lee Soo Min , Yoon Kuk Ro
Published: December 2007

Biodegradable poly(p‐dioxanone) (PPDO) was formed on Wang resin surface by surface‐initiated ring‐opening polymerization (SI‐ROP). The SI‐ROP of p‐dioxanone (PDO) was achieved by heating a mixture of Tin(II) bis(2‐ethylhexanoate) [Sn(Oct)2], hydroxyl functionalized Wang resin, and PDO in anhydrous toluene at 80 °C. The resultant polymer‐grafted Wang resin (Wang‐g‐PPDO) was characterized by fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), optical microscopy (OM), and field‐emission scanning electron microscopy (FE‐SEM). The FTIR spectra of Wang‐g‐PPDO show peak characteristic of PPDO at 2943 cm−1 (CH stretch), at 1741 cm−1 (CO stretch), and 1136 cm−1 (COC stretch) indicating the formation of ester linkage between PPDO and hydroxyl terminated Wang resin. The DSC thermogram show melting peak corresponding to PPDO polymer on Wang resin surface. Thermogravimetric investigation shows increase in PPDO content on the Wang resin surface in terms of percentage of weight loss with increase in reaction time. The OM and SEM photographs clearly show the formation of PPDO polymer on the Wang resin surface without altering the spherical nature of Wang resin bead. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1178–1184, 2008
Vinyl addition polymerization of norbornene using cyclopentadienylzirconium trichloride activated by isobutyl‐modified methylaluminoxane
Authors: Nishizawa Osamu , Misaka Hideki , Kakuchi Toyoji , Satoh Toshifumi
Published: December 2007

Norbornene polymerization using the commercially available and inexpensive catalyst system, cyclopentadienylzirconium trichloride (CpZrCl3) and isobutyl‐modified methylaluminoxane (MMAO), were carried out over a wide range of polymerization temperatures and monomer concentrations. For the CpZrCl3 catalyst system activated by aluminoxane with a 40 mol % methyl group and a 60 mol % isobutyl group (MMAO40/60), the polymerization temperature and monomer concentration significantly affected the molecular weight (Mn) of the obtained polymer and the catalytic activity. With an increase in the polymerization temperature from 0 to 27 °C, the catalytic activity and Mn increased, but these values dramatically decreased with the increasing polymerization temperature from 27 to 70 °C, meaning that the most suitable temperature was 27 °C. The CpZrCl3/MMAO40/60 ([Al]/[Zr] = 1000) catalyst system with the [NB] of 2.76 mol L−1 at 27 °C showed the highest activity of 145 kg molZr−1 h−1 and molecular weight of 211,000 g mol−1. The polymerization using the CpZrCl3/MMAO40/60 catalyst system proceeds through the vinyl addition mechanism to produce atactic polynorbornene, which was soluble in chloroform, toluene, and 1,2‐dichlorobenzene, but insoluble in methanol. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1185–1191, 2008
One‐stage synthesis of narrowly dispersed polymeric core‐shell microspheres
Authors: Wen Fei , Zhang Wangqing , Zheng Peiwen , Zhang Xu , Yang Xinlin , Wang Yao , Jiang Xiaowei , Wei Guanwei , Shi Linqi
Published: December 2007

A method of one‐stage soap‐free emulsion polymerization to synthesize narrowly dispersed core‐shell microspheres is proposed. Following this method, core‐shell microspheres of poly(styrene‐co‐4‐vinylpyridine), poly(styrene‐co‐methyl acrylic acid), and poly[styrene‐co‐2‐(acetoacetoxy)ethyl methacrylate‐co‐methyl acrylic acid] are synthesized by one‐stage soap‐free emulsion polymerization of a mixture of one or two hydrophobic monomers and a suitable hydrophilic monomer in water. The effect of the molar ratio of the hydrophobic monomer to the hydrophilic one on the size, the core thickness, and the shell thickness of the core‐shell microspheres is discussed. The molar ratio of the hydrophobic and hydrophilic monomers and the hydrophilicity of the resultant oligomers of the hydrophilic monomer are optimized to synthesize narrowly dispersed core‐shell microspheres. A possible mechanism of one‐stage soap‐free emulsion polymerization to synthesize core‐shell microspheres is suggested and coagglutination of the oligomers of the hydrophilic monomers on the hydrophobic core is considered to be the key to form core‐shell microspheres. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1192–1202, 2008
Styrene polymerization catalyzed by metal porphyrin complex/MAO for in situ synthesizing polystyrene containing air stable π cation radicals
Authors: Li Jianzhong , Li Min , Li Shiyun , Shi Liya , Ren Changyi , Cui Dongmei , Wang Yanhui , Tang Tao
Published: December 2007

A novel catalyst system based on nickel(II) tetraphenylporphyrin (Ni(II)TPP) and methylaluminoxane for styrene polymerization was developed. This catalyst system has a high thermal stability and show fairly good activity. The obtained polystyrene (PS) was isotactic‐rich atactic polymer by 13C NMR analysis, and its molecular weight distribution was rather narrow (Mw/Mn ≈ 1.6, by GPC analysis). ESR revealed that Ni(II)TPP π cation radicals were formed in the polymerization and could remain in the resulting PS stably. The mechanism of the polymerization was discussed and a special coordination mechanism was proposed. The PS product containing Ni(II)TPP π cation radicals can be used as a potential functional material. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1240–1248, 2008
Precision synthesis of microstructures in star‐shaped copolymers of ϵ‐caprolactone, L‐lactide, and 1,5‐dioxepan‐2‐one
Authors: Odelius Karin , Albertsson Ann‐Christine
Published: December 2007

Star‐shaped homo‐ and copolymers were synthesized in a controlled fashion using two different initiating systems. Homopolymers of ε‐caprolactone, L‐lactide, and 1,5‐dioxepan‐2‐one were firstly polymerized using (I) a spirocyclic tin initiator and (II) stannous octoate (cocatalyst) together with pentaerythritol ethoxylate 15/4 EO/OH (coinitiator), to give polymers with identical core moieties. Our gained understanding of the versatile and controllable initiator systems kinetics, the transesterification reactions occurring, and the role which the reaction conditions play on the material outcome, made it possible to tailor the copolymer microstructure. Two strategies were used to successfully synthesize copolymers of different microstructures with the two initiator systems, i.e., a more multiblock‐ or a block‐structure. The correct choice of the monomer addition order enabled two distinct blocks to be created for the copolymers of poly(DXO‐co‐LLA) and poly(CL‐co‐LLA). In the case of poly(CL‐co‐DXO), multiblock copolymers were created using both systems whereas longer blocks were created with the spirocyclic tin initiator. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 1249–1264, 2008
Synthesis and characterization of novel photoisomerizable liquid crystalline polymers containing cinnamoyl groups
Authors: Yang Po‐Chih , Liu Jui‐Hsiang
Published: December 2007

A series of novel liquid crystalline monomers and polymers incorporating phenylbenzoate or phenylcinnamate segments as mesogenic cores have been synthesized to investigate the sensitivity of the photochromic cinnamoyl derivatives and to overcome the defects of the thermal instability of azobenzene. Their liquid crystalline, thermal, and photoinduced properties of all monomers and polymers were characterized. The polymers showed excellent solubility in common organic solvents such as CHCl3, toluene, and DMF and exhibited good thermal stability with decomposition temperatures (Td) at 5% weight loss greater than 340 °C and about 50% weight loss occurred beyond 430 °C under nitrogen atmosphere. The pitch length (about 574 nm) of the synthesized cholesteric polymeric film (CP2) was estimated using scanning electron microscopy. These photochromic polymers exhibited strong UV–vis absorption maxima at about 264 or 320 nm. Moreover, photo induced configurational E/Z isomerization further changed the π‐electron conjugation systems leading to a decrease at the π‐π* transition and an increase in the range of 300 nm to 400 nm for photochromic copolymers. The thermal stability of the Z‐structural segment was confirmed by heating the polymer at 50 °C for over 5 h. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1289–1304, 2008
Synthesis of conjugated polymers with pendant ruthenium terpyridine trithiocyanato complexes and their applications in heterojunction photovoltaic cells
Authors: Cheng Kai Wing , Mak Chris S. C. , Chan Wai Kin , Ching Ng Alan Man , Djurišić Aleksandra B.
Published: December 2007

Two conjugated polymers based on poly(phenylenethiophene) and poly (fluorenethiophene) main chain functionalized with pendant trithiocyanato ruthenium terpyridine complexes were synthesized by the Suzuki coupling reaction. The ruthenium complexes can extend the absorption band to longer wavelength and enhance the photosensitivity in this region. The polymers exhibit very broad absorption band spanning from 400 to 750 nm due to the presence of π‐conjugated system and the ruthenium complexes. Such enhancement in optical absorption enables the utilization of solar light in the near IR region. By space charge limited current modeling, the hole carrier mobilities of the polymers were calculated to be in the order of 10−4 cm2 V−1 s−1, which greatly facilitate the transport of charges after the separation of excitons. Heterojunction photovoltaic cells with simple structure ITO/polymer/C60/Al were fabricated. Under simulated AM1.5 solar light illumination, the short circuit currents, open circuit voltages, and power conversion efficiencies of the photovoltaic cells were measured to be 1.53–2.58 mA cm−2, 0.12–0.24 V, and 0.084–0.12%, respectively. Deposition of PEDOT:PSS on ITO surface did not show significant difference in device performance. Plot of incident photon to charge efficiency as the function of wavelength suggests that absorption by both conjugated main chain and ruthenium complex are essential to the photocurrent generation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1305–1317, 2008
A new strategy to characterize the extent of reaction of thermoset elastomers
Authors: Webb Antonio R. , Yang Jian , Ameer Guillermo A.
Published: December 2007

A new method for determining the extent of reaction of thermoset elastomers was developed based on equilibrium swelling and dynamic mechanical analysis (DMA). The extent of reaction was defined based on the molecular weight between crosslinks (Mc) of a polymer sample in relation toMcat the onset of gelation and at complete reaction. The molecular weight between crosslinks was measured using equilibrium swelling, whereas rheology and DMA were used to determine the exact point of gelation and reaction completion, respectively. The extent of reaction of poly(1,8‐octanediol‐co‐citrate) at various polymerization conditions was investigated and this method was used to study the relationship between mechanical properties, molecular weight between crosslinks, and extent of reaction. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1318–1328, 2008
Synthesis and thiol–ene photopolymerization of allyl‐ether functionalized dendrimers
Authors: Nilsson Camilla , Simpson Neil , Malkoch Michael , Johansson Mats , Malmström Eva
Published: December 2007

Well‐defined, allyl‐ether functional, first‐generation dendrimers have been synthesized. The convergent growth approach was utilized, using the anhydride of the allyl‐ether terminated building block. Three different core moieties were used: trimethylolpropane, trisphenol, and ditrimethylolpropane. The coupling reactions proceeded in good yields and all compounds were characterized by NMR, MALDI‐TOF, and SEC. The allyl‐terminated dendrimers were crosslinked by thiol–ene chemistry, using a multifunctional thiol, TriThiol, to give clear and smooth films. The photopolymerization was conducted in the presence of a photoinitiator, Irgacure 651, and no traces of either allyl‐ether groups or thiols were observed by FT‐Raman after cure. All crosslinked films were characterized with respect to mechanical (DMA) and thermal (DSC) properties. It was found that homogeneous networks were formed and that the core functionality and structure had little effect on the network properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1339–1348, 2008
Conjugated polymers containing electron‐transporting, hole‐transporting, and light‐emitting units in the polymer main chain
Authors: Fu Yaqin , Sun Minghao , Wu Yonggang , Bo Zhishan , Ma Dongge
Published: December 2007

Conjugated polymers containing electron‐transporting, hole‐transporting, and blue light‐emitting units were synthesized by Suzuki polycondensation. These copolymers exhibited excellent thermal and optical stability. Optical investigation indicated that the incorporation of the spirobifluorene units in the polymer main chain could markedly increase the effective conjugation length of polymers. Electrochemical studies showed that the incorporation of spirobifluorene unit could raise the electrochemical stability and improve the electron‐ and hole‐injecting abilities. The electroluminescent results also showed that the introducing of spirobifluorene units could significantly improve the device performance. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1349–1356, 2008
Alkyl side chain driven tunable red–yellow–green emission: Investigation on the new π‐conjugated polymers comprising of 2,7‐carbazole unit and 2,1,3‐benzo‐thiadiazole units with different side chains
Authors: Du Junping , Xu Erjian , Zhong Hongliang , Yu Feng , Liu Chang , Wu Huanrong , Zeng Danli , Ren Shijie , Sun Jing , Liu Yingchun , Cao Amin , Fang Qiang
Published: December 2007

Four new soluble polymers containing a 2,7‐carbazole unit and a 2,1,3‐benzothiadiazole unit in the main chain were synthesized by Suzuki polycondensation. Variation of the substituent groups (R) at 5‐position of 2,1,3‐benzothiadiazole unit resulted in different color emission of the copolymers. Thus, when R was CH3 (or H), the polymer showed yellow–green (or red) emission; whereas the polymers showed the emission from green to yellow–green, when R was CH2(CH2)5CH3 or CH2OCH(CH3)2. To investigate the nature of the color change, a Gaussian 03 program was used for estimation of the dihedral angles between a 5‐R‐2,1,3‐benzothiadiazole unit and a 2,7‐carbazole unit. The results showed that the different substituents at 5‐position of 2,1,3‐benzothiadiazole brought about different the dihedral angles, which gave the different conjugation levels to the polymers. Hence, the tunablity of emission color may be attributed to the different conjugation levels between 2,7‐carbazole units and 5‐R‐2,1,3‐benzothiadiazole units induced by simply changing substituent groups at 5‐position of benzothiadiazole unit. Electrochemically, the copolymers exhibited a higher oxidation potential as well as the reversible reduction behavior bearing from 2,1,3‐benzothiadiazole unit. To investigate the electroluminescent properties of the polymers, the nonoptimized devices were fabricated and the results showed that the electroluminescent emission wavelength was basically similar to that of the photoluminescent. All polymers showed good thermal stability with 5 wt % loss temperature of more than 296 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1376–1387, 2008
Synthesis and micellization of star‐like hyperbranched polymer with poly(ethylene oxide) and poly(ε‐caprolactone) arms
Authors: Wang Huan‐Bing , Chen Xue‐Si , Pan Cai‐Yuan
Published: December 2007

Novel star‐like hyperbranched polymers with amphiphilic arms were synthesized via three steps. Hyperbranched poly(amido amine)s containing secondary amine and hydroxyl groups were successfully synthesized via Michael addition polymerization of triacrylamide (TT) and 3‐amino‐1,2‐propanediol (APD) with feed molar ratio of 1:2. 1H, 13C, and HSQC NMR techniques were used to clarify polymerization mechanism and the structures of the resultant hyperbranched polymers. Methoxyl poly(ethylene oxide) acrylate (A‐MPEO) and carboxylic acid‐terminated poly(ε‐caprolactone) (PCL) were sequentially reacted with secondary amine and hydroxyl group, and the core–shell structures with poly(1TT‐2APD) as core and two distinguishing polymer chains, PEO and PCL, as shell were constructed. The star‐like hyperbranched polymers have different sizes in dimethyl sulfonate, chloroform, and deionized water, which were characterized by DLS and 1H NMR. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1388–1401, 2008
The effect of γ‐cyclodextrin addition in the self‐assembly behavior of pyrene labeled poly(acrylic) acid with different chain sizes
Authors: Costa Telma , Seixas de Melo J. S.
Published: December 2007

The interaction between poly(acrylic acid) polymers (PAA) of low‐ (2000 g/mol) and high‐ (450,000 g/mol) molecular weight (Mw) hydrophobically modified with pyrene (PAAMePy) and β‐ and γ‐cyclodextrins (β‐CD, γ‐CD) was investigated with fluorescent techniques. The interaction with β‐CD promotes little variation in the spectral and photophysical behavior of the polymer, whereas significant changes are observed upon addition of γ‐CD. The degree of inclusion (between the pyrene groups of the polymer and the cyclodextrins) is followed through the observation of the changes in the absorption, excitation (collected in the monomer and excimer emission regions) and emission (IE/IM ratio) spectra and from time‐resolved data. Within the studied range of γ‐CD concentration, the fluorescence decays of the long chain (high Mw) PAAMePy polymers were found tri‐exponential in the monomer and excimer emission regions in agreement with previous studies. In the case of the low Mw PAAMePy polymers, tri‐exponential decays were observed at the monomer and excimer emission wavelengths. However, when a γ‐CD concentration of 0.01 and 0.03 M is reached for, respectively, the low‐ and high‐labeled pyrene short chain (low Mw) polymers, the fluorescence decays in the excimer region become biexponential (two excimers) with no rising component, thus showing that all pyrene groups are encapsulated (and preassociated) into the γ‐CD cavity. In the case of the high Mw polymers, the addition of γ‐CD has been found to change the level of polymer interaction from pure intramolecular (water in the absence of cyclodextrin) to a coexistence of intra‐ with intermolecular interactions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1402–1415, 2008
Thermally latent polyaddition and curing of Di‐ and tri‐functional hemiacetal esters with diepoxide by salen‐zinc complex with tunable catalytic activity and model and networking reactions
Authors: Komatsu Hiroyuki , Ochiai Bungo , Endo Takeshi
Published: December 2007

Salen‐zinc complexes (Zn/1R) thermal‐latently catalyzed the polyaddition of a diepoxide (2) with a difunctional hemiacetal ester (3), which proceeded at moderate temperatures (100–150 °C) for curing of mixtures containing monomers and initiators. The catalytic activities of Zn/1R depended on the Lewis acidities of the complexes controlled by the electronic character of the salen ligands. For example, Zn/13,5‐Cl bearing four electron‐withdrawing chlorine atoms initiated the polyaddition at the lowest temperature (100 °C), and Zn/1OMe bearing two electron‐donating methoxy groups initiated the polyaddition at 120 °C. The Lewis acidities of the complexes were evaluated by NMR and IR spectroscopies and computational calculation. The polyadditions with the salen‐zinc complexes proceeded quantitatively at 150 °C, and the use of a tri‐functional hemiacetal ester (7) with 2 afforded the corresponding networked polymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1427–1439, 2008
Polysaccharide‐templated twisted assemble of 2‐anilinonaphthalene‐6‐sulfonic acid
Authors: Shimada Naohiko , Okobira Tadashi , Takeda Yoichi , Shinkai Seiji , Sakurai Kazuo
Published: December 2007

Schizophyllan (SPG) is a natural β‐1,3‐glucan that forms a triple helix (t‐SPG) in neutral aqueous solutions and t‐SPG can be denatured to single chains (s‐SPGs) in DMSO or alkaline solutions. Exchanging the denatured solutions for neutral water leads the renaturation of the triple helix. We have reported that hydrophobic molecules can form a complex with s‐SPG when they are present in the renaturation process. Some of these, for example poly(dA) and polyaniline, were found to have aromatic amino moieties. This report demonstrates whether s‐SPG can interact with other aromatic amino compounds such as anilinonaphthalene sulfonic acid (ANS) derivatives. Enhanced fluorescence intensity and red‐shifted UV absorption spectra were observed in the mixture of s‐SPG and 2,6‐ANS or 2,6‐TNS. In the circular dichroism measurement, the positive Cotton effects appeared after mixing 2, 6‐ANS with s‐SPG. When the amino proton was replaced by the methyl group or used in intramolecular hydrogen bonds, any spectral changes were not observed. These results indicate that amino proton in the ANS derivatives plays a key role in the complexation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1440–1448, 2008
Branched polymer via free radical polymerization of chain transfer monomer: A theoretical and experimental investigation
Authors: Liu Jianhua , Wang Yusong , Fu Qi , Zhu Xiangyang , Shi Wenfang
Published: December 2007

A simple mathematic model for the free radical polymerization of chain transfer monomers containing both polymerizable vinyl groups and telogen groups was proposed. The molecular architecture of the obtained polymer can be prognosticated according to the developed model, which was validated experimentally by homopolymerization of 4‐vinyl benzyl thiol (VBT) and its copolymerization with styrene. The chain transfer constant (CT) of telogen group in a chain transfer monomer is considered to play an important role to determine the architecture of obtained polymer according to the proposed model, either in homopolymerization or copolymerization. A highly branched polymer will be formed when the CT value is around unity, while a linear polymer with a certain extent of side chains will be obtained when the CT value is much bigger or smaller than unity. The CT of VBT was determined to be around 15 by using the developed model and 1H NMR monitored experiments. The obtained poly(VBT) and its copolymers were substantiated to be mainly consisted of linear main chain with side branching chains, which is in agreement with the anticipation from the developed model. The glass transition temperature, number average molecular weight, and its distribution of those obtained polymer were primarily investigated. This model is hopefully to be used as a strategy to select appropriate chain transfer monomers for preparing hyperbranched polymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1449–1459, 2008
Propagation kinetics of free‐radical polymerizations in ionic liquids
Authors: Woecht Inga , Schmidt‐Naake Gudrun , Beuermann Sabine , Buback Michael , García Nuria
Published: December 2007

Propagation rate coefficients,kp, of methyl methacrylate (MMA) and glycidyl methacrylate (GMA) homopolymerizations were measured at ambient pressure in four ionic liquids (ILs): 1‐ethyl‐3‐methylimidazolium ([emim]) ethyl sulfate and [emim] hexyl sulfate as well as butyl‐3‐methylimidazolium ([bmim]) hexafluorophosphate and [bmim] tetrafluoroborate via the pulsed‐laser polymerization size‐exclusion chromatography technique. In passing from bulk polymerization at 40 °C polymerization in IL solution containing 20 vol % monomer,kpis enhanced by up to a factor of 4 with MMA and by a factor of 2 with GMA. This enhancement ofkpprimarily results from a lowering of activation energy upon partial replacement of monomer by ionic liquid species. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1460–1469, 2008
Fluorescent polymer particles incorporating pyrene derivatives
Authors: Tamai Toshiyuki , Watanabe Mitsuru , Maeda Hajime , Mizuno Kazuhiko
Published: December 2007

Fluorescent polymer particles incorporating pyrene and alkynylpyrenes were prepared by miniemulsion polymerization of styrene. The pyrenes were simply dissolved in styrene monomer and then added to the reaction mixture in a vessel, followed by ultrasonication and the polymerization. The pyrenes were incorporated in the polystyrene particles and gave monomer fluorescence emission. The fluorescent particles incorporating the alkynylpyrenes, which have high fluorescence quantum yield and short fluorescence lifetime, showed the same fluorescence emission intensity under air and nitrogen. The fluorescence of the alkynylpyrenes in the polymer particles will not be quenched by molecular dioxygen in contrast to that in organic solvents. Incorporation of fluorophore into polymer particles will protect the fluorophore from its undesirable interaction with oxygen, affording the particles highly fluorescent even under air. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1470–1475, 2008
Styrene/1,3‐butadiene copolymerization by C2‐symmetric group 4 metallocenes based catalysts
Authors: Napoli Mariagrazia , Ricciardi Rosa , Memoli Antonia , Longo Pasquale
Published: December 2007

C2‐symmetric group 4 metallocenes based catalysts (rac‐[CH2(3‐tert‐butyl‐1‐indenyl)2]ZrCl2(1), rac‐[CH2(1‐indenyl)2]ZrCl2(2) and rac‐[CH2(3‐tert‐butyl‐1‐indenyl)2]TiCl2(3)) are able to copolymerize styrene and 1,3‐butadiene, to give products with high molecular weight. In agreement with symmetry properties of metallocene precatalysts, styrene homosequences are in isotactic arrangements. Full determination of microstructure of copolymers was obtained by 13C NMR and FTIR analysis and it reveals that insertion of butadiene on styrene chain‐end happens prevailingly with 1,4‐trans configuration. In the butadiene homosequences, using zirconocene‐based catalysts, the 1,4‐trans arrangement is favored over 1,4‐cis, but the latter is prevailing in the presence of titanocene (3). Diad composition analysis of the copolymers makes possible to estimate the reactivity ratios of copolymerization: zirconocenes (1) and (2) produced copolymers having r1 × r2 = 0.5 and 3.0, respectively (where 1 refers to styrene and 2 to butadiene); while titanocene (3) gave tendencially blocky styrene–butadiene copolymers (r1 × r2 = 8.5). The copolymers do not exhibit crystallinity, even when they contain a high molar fraction of styrene. Probably, comonomer homosequences are too short to crystallize (ns = 16, in the copolymer at highest styrene molar fraction). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1476–1487, 2008
Styrene‐ethylene co‐oligomerization with bis‐(diphenylphosphino)‐amine/chromium catalysts and the use of the co‐oligomerization products in copolymerization reactions with metallocenes
Authors: Du Toit Aletta , De Wet‐Roos Deon , Joubert Dawie J. , Van Reenen Albert J.
Published: December 2007

Ethylene‐styrene (or 4‐methylstyrene) co‐oligomerization using various bis(diphenylphoshino)amine ligands in combination with chromium is discussed. GC analysis of the reaction mixture shows that various phenyl‐hexene and phenyl‐octene isomers are formed either through cotrimerization or cotetramerization. It seems that the more bulky ligands display lower selectivity to co‐oligomerization and favor ethylene homo‐oligomerization. Subsequent copolymerization of the oligomerization reaction mixture using a metallocene polymerization catalyst results in a copolymer with a branched structure as indicated by Crystaf and 13C NMR analysis. Assignments of the 13C NMR spectrum are proposed from an APT NMR experiment combined with calculated NMR chemical shift data using additivity rules. An indication of the ability of the different co‐oligomerization products to copolymerize into the polyethylene chain could be established from these assignments. Unreacted styrene and the more bulky isomers, 3‐phenyl‐1‐hexene and 3‐phenyl‐1‐octene, are not readily incorporated while branches resulting from the other isomers present in the co‐oligomerization reaction mixture are detected in the NMR spectrum. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 1488–1501, 2008
High‐throughput kinetic analysis of acrylate and thiol‐ene photopolymerization using temperature and exposure time gradients
Authors: Johnson Peter M. , Stansbury Jeffrey W. , Bowman Christopher N.
Published: December 2007

In this work, a high‐throughput technique for evaluating photopolymers is developed to enable simultaneous measurement of the effects of temperature in combination with exposure time. Temperature and exposure time gradients were produced in orthogonal directions on a single sample, and subsequently sampled using Fourier transform infrared (FTIR) spectroscopy. The technique developed here allows for photopolymerization kinetics to be analyzed rapidly over a large range of industrially relevant temperatures, giving insight into the role temperature and the polymer's glass transition temperature have in dictating the photopolymerization kinetics. In the 70/30 wt % hexyl acrylate and hexanediol diacrylate system, conversion in samples below the glass transition temperature (TG) was 66 ± 2% after 12 s, significantly lower than the 93 ± 4% conversion at 12 s for samples polymerized at temperatures above the TG. In addition, a thiol‐ene system was analyzed to study the effect of temperature on the ene homopolymerization in allyl ether monomers, which leads to incomplete thiol conversion in stoichiometrically balanced systems. At a 60% thiol conversion, the allyl ether‐ene conversion at all temperatures is 65 ± 3% irrespective of initial formulation temperature, indicative of the homopolymerization behavior being nearly independent of temperature. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1502–1509, 2008
Synthesis and properties of highly refractive polyimides derived from fluorene‐bridged sulfur‐containing dianhydrides and diamines
Authors: Terraza Claudio A. , Liu Jin‐Gang , Nakamura Yasuhiro , Shibasaki Yuji , Ando Shinji , Ueda Mitsuru
Published: December 2007

Highly refractive and transparent polyimides (PIs) based on fluorene‐bridged and sulfur‐containing monomers have been developed. An aromatic dianhydride, 4,4′‐[p‐thiobis(phenylenesulfanyl)]diphthalic anhydride (3SDEA), was polymerized with several fluorene‐containing diamines, including commercially available 9,9′‐bis(p‐aminophenyl)fluorene (APF), 9,9′‐bis[4‐(p‐aminophenoxy)phenyl]fluorene (OAPF), and newly synthesized 9,9′‐bis[4‐(p‐aminophenyl)sulfanylphenyl]fluorene (ASPF) to afford series A PIs. Meanwhile, series B PIs were obtained from a new dianhydride, 4,4′‐[(9H‐fluorene‐9‐ylidene)bis(p‐phenylsulfanyl)]diphthalic anhydride (FPSP) and two aromatic diamines, ASPF and 4,4′‐thiobis[(p‐phenylenesulfanyl)aniline] (3SDA) via a two‐step polycondensation procedure. The PIs exhibit good thermal stabilities, such as relatively high glass transition temperatures in the range of 220–270 °C and high initial thermal decomposition temperatures (T10%) exceeding 490 °C. The 9,9′‐disubstituted fluorene moieties endow the PI films with good optical transparency. The optical transmittances of the PI films at 450 nm are all higher than 80% for the thickness of about 10 μm. Furthermore, the highly aromatic fluorene moiety and flexible thioether linkages in the molecular chains of the PIs provide them with high refractive indices of 1.6951–1.7258 and small birefringence of 0.0056–0.0070. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1510–1520, 2008
Synthesis of chalcone‐based fluorescent polymers: Diels‐Alder reaction of chalcones and their polymerization through ROMP
Authors: Kamakshi R. , Reddy B. S. R.
Published: December 2007

Ring opening metathesis polymerization (ROMP) was carried out on Diels‐Alder adducts formed from reactions between chalcones and cyclopentadiene. Most of the chalcones gave predominantly endo‐adducts and the exo‐adducts were obtained in good yields from reacting cyclopentadiene with furfurylidine acetone and N,N,diethylaminobenzylidine‐(4‐hydroxy)acetophenone. These exo‐adducts were subjected to ROMP using Grubbs catalyst, bis(tricyclohexylphosphine)benzylidinedichloride. The monomers and polymers were characterized using spectroscopic techniques like FT‐IR, 1HNMR. The polymers were characterized using TGA, DSC, and GPC. The polymers were found to possess fluorescent properties and poly[2‐(4‐diethylamino)phenyl‐3,5‐divinylcyclopentyl](4‐hydroxyphenyl) methanone was found to have good emissive property at two wavelengths. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1521–1531, 2008
Cyclic oligomer chemistry
Authors: Brunelle Daniel J.
Published: December 2007

Cyclic oligomers of engineering plastics such as polycarbonate and aromatic polyesters have been known for some time, being formed at very low levels during commercial manufacture. At GE Global Research, we have devised methods for high‐yielding and selective preparation of such cyclic oligomers, that are amenable to commercial manufacture. The mixtures of cyclic oligomers have melting points significantly lower than individual ring sizes, and have very low viscosities in the melt. Ring‐opening polymerization using appropriate initiators affords rapid reactions (2–6 min) without measurable exotherm, providing very high‐molecular‐weight polymers and without reaction byproducts. These materials have been scaled to commercial quantities, and have shown to be extremely useful for fabrication of glass and carbon fiber composites with high‐fiber fractions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1151–1164, 2008
Dynamic mechanical and rheological properties of binary S–(S/B)–S triblock copolymer blends
Authors: Thunga M. , Satapathy B. K. , Staudinger U. , Weidisch R. , Abdel‐Goad M. , Janke A. , Knoll K.
Published: December 2007

The rheology and dynamic mechanical properties of binary block copolymer blends consisting of a symmetrical triblock copolymer with thermoplastic elastomeric behavior (LN4) and an asymmetrical thermoplastic triblock copolymer (LN3) were investigated. TEM images of the blends show a systematic variation in the morphologies from worms (∼20–0 wt % LN3) to cylinders (∼60–30 wt % LN3) to lamellae (100–70 wt % LN3) as a function of LN3 content. DMA analysis has revealed that the increase in LN3 content leads to a decrease in miscibility between the PS end blocks and the S/B middle block. The frequency and temperature dependence of the storage modulus (G′), loss modulus (G″), and complex viscosity (|η*|) has been studied for LN4 (weakly segregated) and LN3 (strongly segregated) from their master curves. By comparing the rheological properties of these blend compositions at low‐frequency regime, it is observed that with the increase in LN3 content the shear modulus and complex viscosity increase. Blend compositions with 70–100 wt % of LN3 show nonterminal behavior at reduced frequencies due to the presence of highly ordered microdomains when compared to blends with ∼0–20 wt % of LN3 content. van Gurp–Palmen plots were constructed to observe the transition from liquid‐ to solid‐like behavior in the vicinity of order‐to‐disorder transition (ODT) temperature. ODT temperature increases as the thermoplastic LN3 content increases which are also confirmed by the Han plots. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 329–343, 2008
Mean‐field theoretical analysis of brush‐coated nanoparticle dispersion in polymer matrices
Authors: Harton Shane E. , Kumar Sanat K.
Published: December 2007

The equilibrium dispersion of nanoparticles with grafted polymer chains into polymer matrices, of the same chemical structure as the brush, is studied through the device of mean‐field theory. Our results show that the disperion of brush‐coated nanoparticles into a matrix polymer is improved with (i) decreasing particle radius and (ii) increasing brush chain length. Both of these aspects can be understood based on the fact that, unlike the case of planar surfaces, homopolymer chains end‐grafted to spherical nanoparticle surfaces tangentially spread away from the surface thus alleviating the packing frustration that is created by the relatively high grafting densities. This permits significant brush/matrix overlap, even at high grafting densities, a regime that has only recently become experimentally available due to advances in polymer synthesis (i.e., the “grafting‐to” methods). © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 351–358, 2008
Electrical and dielectric properties in carbon fiber‐filled LMWPE/UHMWPE composites with different blend ratios
Authors: Chen Qingyun , Xi Ying , Bin Yuezhen , Matsuo Masaru
Published: December 2007

Carbon fiber (CF) filled low‐molecular‐weight polyethylene (LMWPE) and ultra‐high molecular weight polyethylene (UHMWPE) composites were prepared by the gelation from solution and the kneading in the melting state. The content of carbon fibers was fixed to be 23.5 vol %. The resistivity, positive temperature coefficient (PTC), and dielectric behaviors of the composites became more pronounced with increasing content of LMWPE with much higher thermal expansion than that of UHMWPE. The PTC effect became most significant, when the blend ratio of LMWPE to UHMWPE was 9/1. Beyond 9/1, the PTC effect was less pronounced. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) revealed that the UHMWPE and LMWPE chains within the composite crystallized independently by gelation from solution and were virtually unaffected by the presence of carbon fibers. Consequently, it was confirmed that carbon fibers selectively were localized in the mixed region of LMWPE and UHMWPE for the composite (3/1 and 6/1) and mainly in the region of LMWPE for the 9/1, 12/1, and 15/1 composites. This indicated that the content of carbon fibers within LMWPE region was the highest for the 9/1 composite and the 9/1 composite provides the most significant PTC effect. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 359–369, 2008
Phase behavior of a single polyethylene chain confined between two adsorption walls
Authors: Su Jiaye , Zhang Linxi
Published: December 2007

The phase behavior of a single polyethylene chain confined between two adsorption walls is investigated by using molecular dynamics simulations. In the free space, it is confirmed in our calculation that the isolated polymer chain exhibits a disordered coil state at high temperatures, and collapses into a condensed state at low temperatures, that is, the coil‐to‐globule transition, and the finite chain length effects are considered since the critical region depends on chain lengths. When the chain is confined between two attractive walls, however, the equilibrium properties not only depend on the chain length but also depend on the adsorption energy and the confinement. Mainly, we focus on the influence of polymer chain length, confinement, and adsorption interaction on the equilibrium thermodynamic properties of the polyethylene chains. Chain lengths of N = 40, 80, and 120 beads, distances between the two walls of D = 10, 20, 30, 50, and 90 Å, and adsorption energies of w = 1.5, 2.5, 3.5, 6.5, and 8.5 kcal/mol are considered here. By considering the confinement–adsorption interactions, some new folding structures are found, that is, the hairpin structure for short chain of N = 40 beads, and the enhanced hairpin or crystal like structures for long chains of N = 80 and 120 beads. The results obtained in our simulations may provide some insights into the phase behaviors of confined polymers, which can not be obtained by previous studies without considering confinement–adsorption interactions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 370–387, 2008