bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of cyclooxygenase isoforms in normal human skin and chronic venous ulcers
Authors: Abd‐El‐Aleem Seham A. , Ferguson Mark W. J. , Appleton Ian , Bhowmick Arnab , McCollum Charles N. , Ireland Grenham W.
Published: August 2002

Chronic venous ulcers are an example of abnormal wound healing showing chronic inflammation which together with the underlying vascular pathology results in delayed healing. Prostaglandins are among the most important mediators of inflammation. They have proinflammatory effects, predominantly by affecting the vasculature. Cyclooxygenase (COX) is the rate‐limiting enzyme in prostanoid synthesis. It is present in two isoforms: COX‐1 (constitutive cyclooxygenase) which is produced in the body to maintain normal haemostatic functions, and COX‐2 (inducible cyclooxygenase), which is induced during inflammation in response to cytokines. Using immunoenzymatic labelling and western blot analysis, this study has shown that both COX‐1 and COX‐2 were up‐regulated in chronic venous leg ulcers by comparison with normal human skin. De novo appearance of COX‐2 in chronic venous ulcers was demonstrated, which is not seen in normal human skin. The main cellular sources of both COX isoforms are macrophages and endothelial cells. COX‐2 is also produced by mast cells and fibroblasts. A COX radioimmunoassay showed up‐regulation of COX activity in chronic venous ulcers compared with normal skin (p<0.05). Up‐regulation of COX‐1 in chronic venous leg ulcers could produce prostacyclin, which contributes to angiogenesis. Thus, inhibition of COX‐1 by non‐steroidal anti‐inflammatory drugs (NSAIDs) could increase the local ischaemia and hypoxia associated with chronic venous ulcers. On the other hand, up‐regulation of COX‐2 is most likely responsible for the persistent inflammation in chronic venous leg ulcers. COX‐2 selective inhibitors could therefore be effective in the treatment of chronic venous ulcers. Copyright © 2001 John Wiley & Sons, Ltd.
Effects of the extracellular matrix on lumican expression in rat aortic smooth muscle cells in vitro
Authors: Qin Hanjuan , Ishiwata Toshiyuki , Asano Goro
Published: August 2002

Lumican is a small leucine‐rich proteoglycan (SLRP), which contributes to cell migration, proliferation, tissue hydration, and collagen fibrillogenesis. Whether lumican is localized in rat aortic smooth muscle cells (SMCs) and what its relationships might be to other extracellular matrix components have not yet been elucidated. In this study, using reverse transcription‐polymerase chain reaction (RT‐PCR), competitive RT‐PCR, and western blot, lumican messenger ribonucleic acid (mRNA) was expressed in cultured rat aortic SMCs. SMCs cultured in serum‐free medium showed four bands at 68, 62, 50, and 37 kD. The 68 and 62 kD bands corresponded to proteoglycan, the 50 kD band to glycoprotein, and the 37 kD band to the core protein form of lumican. The relationships of lumican to fibronectin and laminin were also investigated. The lumican mRNA level in SMCs cultured on fibronectin was highest at day 1, but it increased at day 3 in SMCs cultured on laminin. On the fibronectin or laminin‐coated plates, SMCs expressed only the 68 and 62 kD bands, corresponding to proteoglycan. Pretreatment with anti‐β1 integrin receptor antibody revealed a decrease in the proteoglycan forms of lumican protein and an additional two bands at 50 and 37 kD, indicating glycoprotein and the core protein of lumican. These results show that lumican was synthesized in cultured rat aortic SMCs as proteoglycan, glycoprotein, and core protein. The extracellular matrix (ECM) affected lumican protein production and restricted the lumican protein form to proteoglycan via the β1 integrin receptor in SMCs. Copyright © 2001 John Wiley & Sons, Ltd.
Quantification of the production of dihydrokaempferol by flavanone 3‐hydroxytransferase using capillary electrophoresis
Authors: Owens Daniel K. , Hale Tracy , Wilson Lori J. , McIntosh Cecilia A.
Published: August 2002

A sensitive method using capillary electrophoresis for the separation, detection, and quantification of dihydrokaempferol (1) is reported. Well‐resolved, sharp symmetrical peaks were obtained in grapefruit leaf extracts for 1, naringenin (2), and the internal standard, naringin (3). Long columns were required to resolve 1 from 2 in crude enzyme reactions and this resulted in run times of 60 min. The limit of detection for 1 was found to be 1.44 ng/µL (4.2 pg). The method showed excellent linearity and reproducibility. The method was used to determine the activity of flavanone 3‐hydroxytransferase (F3H) in leaf tissue of grapefruit by quantification of the production of dihydrokaempferol in controlled time course reactions. The sensitivity of the method makes it adaptable to assaying F3H activity in individual young seedlings and/or in small tissue samples and requires only 100 mg of tissue. Copyright © 2002 John Wiley & Sons, Ltd.
Prenatal diagnosis of hydrocephalus‐stenosis of the aqueduct of Sylvius by ultrasound in the first trimester of pregnancy. Report of two cases
Authors: Senat M. V. , Bernard J. P. , Delezoide A. , Saugier‐Veber P. , Hillion Y. , Roume J. , Ville Y.
Published: August 2002

Hydrocephalus‐stenosis of the acqueduct of Sylvius sequence (HSAS) is characterized by hydrocephalus, macrocephaly, adducted thumbs, spasticity, agenesis of the corpus callosum and mental retardation. X‐linked hydrocephalus is known to be due to mutations in the gene coding for the neural cell adhesion molecule L1 (L1‐CAM) and diagnosis is made by identification of a mutation in the L1‐CAM gene. Prenatal diagnosis of HSAS is usually suggested on ultrasound examination showing hydrocephalus in a male fetus associated with bilateral adducted thumbs. Mutation screening of the L1‐CAM gene is indicated when neuropathological examination shows hypoplasia of the corticospinal tract associated with aqueductal stenosis. We report here two cases of HSAS diagnosed within the same family by ultrasound examination in the first trimester of pregnancy when bilateral adducted thumbs were the only early ultrasound marker. Copyright © 2001 John Wiley & Sons, Ltd.
Middle cerebral artery Doppler study in fetuses with homozygous α‐thalassaemia‐1 at 12–13 weeks of gestation
Authors: Hang Lam Yung , Hoi Yin Tang Mary
Published: August 2002

Objective

Fetuses affected by homozygous α‐thalassaemia‐1 are anaemic from the first trimester of pregnancy. We investigated middle cerebral artery Doppler velocimetry in these affected fetuses at 12–13 weeks of gestation to assess its use in predicting fetal anaemia.

Methods

Women referred for the prenatal diagnosis of homozygous α‐thalassaemia‐1 before 14 weeks of gestation were recruited. All fetuses underwent pulsed Doppler examinations following colour flow mapping at 12 or 13 weeks of gestation. Homozygous α‐thalassaemia‐1 was diagnosed by DNA or haemoglobin study. The middle cerebral artery Doppler indices were compared between the affected fetuses and fetuses unaffected by homozygous α‐thalassaemia‐1.

Results

Between 1998 and 2000, 80 eligible women were recruited. Of these, 19 fetuses were affected by homozygous α‐thalassaemia‐1. Two of them showed hydropic changes at the time of Doppler study. The affected fetuses had significantly higher middle cerebral artery peak systolic velocity (Vmax) (36% increase) and time‐averaged maximum velocity (Vtamx) (33% increase).

Conclusion

The increase of cerebral blood flow in affected fetuses is consistent with our previous finding of an increased forward flow in the ductus venosus, cardiac dilatation and an increase of cardiac output to preferentially shunt more oxygenated blood to the brain as a compensatory mechanism. However, extensive overlap of the middle cerebral artery flow velocity values between affected and unaffected fetuses precludes its use in predicting anaemia at 12–13 weeks' gestation. Copyright © 2002 John Wiley & Sons, Ltd.
Ultrasound diagnosis of structural abnormalities in the first trimester
Authors: Dugoff Lorraine
Published: August 2002

The advances in ultrasound technology have made it possible to identify fetal structural abnormalities and genetic syndromes in the first trimester. First trimester prenatal diagnosis of fetal central nervous system, renal, gastrointestinal, cardiac, and skeletal abnormalities is reviewed. Copyright © 2002 John Wiley & Sons, Ltd.
The effect of fast reporting by amnio‐PCR on anxiety levels in women with positive biochemical screening for Down syndrome — a randomized controlled trial
Authors: Cheong Leung Wing , Hang Lam Yung , Wong Ying , T. Lau Elizabeth , Hoi Yin Tang Mary
Published: August 2002

Objective

To study the effect of fast reporting by polymerase chain reaction on amniotic fluid cells (amnio‐PCR) on anxiety levels in women with positive biochemical screening for Down syndrome.

Method

Between May 2000 and April 2001, 60 screen‐positive women were randomized before amniocentesis into either having (group A) or not having (group B) fast‐reporting by amnio‐PCR. Anxiety levels were measured by the Spielberger State‐Trait Anxiety Inventory just prior to amniocentesis, three days (when PCR results were known to group A) and three weeks (when standard karyotype results were known to both groups) afterwards.

Results

Two women were excluded because in one woman amnio‐PCR showed trisomy 21 and the other miscarried shortly after amniocentesis. The state‐anxiety scores increased over the three‐week period after being informed of the positive‐screen result in both groups. The trait‐ and state‐anxiety scores at all points did not differ between the two groups.

Conclusions

In contrast to the general belief, fast reporting by amnio‐PCR did not alleviate anxiety in women who are screen‐positive for Down syndrome. Copyright © 2002 John Wiley & Sons, Ltd.
Dyslipidaemia and diabetes
Authors: John Betteridge D.
Published: August 2002

Dyslipidaemia, characterized by hypertriglyceridaemia, low HDL cholesterol, the accumulation of remnant particles and small dense LDL, is one of the major risk factors contributing to the burden of macrovascular disease in type 2 diabetes. It is open to therapeutic intervention by lifestyle and lipid‐lowering drugs and goals for lipid and lipoprotein concentrations are now included in international guidelines for patient management. There is good evidence from subgroup analyses of major coronary heart disease (CHD) secondary prevention trials that lipid‐lowering drugs are beneficial in diabetic patients. Less information is available for primary prevention and the results of on‐going trials performed specifically in diabetic populations are awaited. Nevertheless many patients will fulfil the absolute CHD risk criteria for primary prevention with lipid‐lowering drugs. Copyright © 2001 John Wiley & Sons, Ltd.
Effect of electron‐beam irradiation on poly(vinyl chloride)/epoxidized natural rubber blend: dynamic mechanical analysis
Authors: Ratnam Chantara Thevy , Nasir Mohd , Baharin Azhari , Zaman Khairul
Published: August 2002

The irradiation‐induced crosslinking in 50/50 poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blend was investigated by means of dynamic mechanical analysis. The influence of trimethylolpropane triacrylate on the irradiation‐induced crosslinking of PVC/ENR blends was also studied. The enhancement in storage modulus and Tg with irradiation dose indicated the formation of irradiation‐induced crosslinks. This is further supported by the decrease in tan δmax and loss modulus peak. The compatibility of the blend was found to be improved upon irradiation. The Fox model was used to provide a further insight into the irradiation‐induced compatibility in the blend. Scanning electron microscopy studies on the cryofracture surface morphology of the blends as well as the homopolymer have been undertaken in order to gain more evidence on the irradiation‐induced crosslinking.

© 2001 Society of Chemical Industry
Associating behaviour of polyacrylamide modified with a new hydrophobic zwitterionic monomer
Authors: Grassl Bruno , Francois Jeanne , Billon Laurent
Published: August 2002

The nucleophilic ring opening of dicyanoketene ethylene acetal by tertiary amino monomers leads to an hydrophobic zwitterionic monomer [(dimethylammonioethoxy)dicyanoethenolate]propylmethacrylamide (DADPMA) characterized by a very high dipole moment. Hydrophobically modified water soluble polymers have been prepared by classical radical polymerization of acrylamide and DADPMA either in homogeneous medium (water/ethanol mixtures) or in micellar solution (water containing sodium dodecylsulphate (SDS)). The copolymers obtained have a high molecular weight (M
w = 2–5 × 106 g mol−1) and are water soluble for a content of DADPMA lower than 1% mole/mole. The properties of the copolymers in aqueous solution depend on the synthesis conditions, especially on the ratio ethanol:zwitterionic monomer.

© 2001 Society of Chemical Industry
Optically active poly(ester‐amide)s: synthesis and characterization
Authors: Philip Biju , Sreekumar K
Published: August 2002

The synthesis and characterization of a new series of chiral poly(ester‐amide)s are reported. They were prepared by the simple reaction of diacid chlorides with biphenolic azo chromophores and optically active dihydroxy compound (isosorbide) in dimethyl acetamide at 100 °C. The polymers containing isosorbide units were optically active. The polymers showed Tg between 100 and 190 °C and were stable up to 400 °C. These poly(ester‐amide)s showed a positive solvatochromism in UV–visible absorption spectra. Second harmonic generation activities were measured by the powder method.

© 2001 Society of Chemical Industry
Influence of experimental variables on thermally stimulated recovery results: analysis of simulations and real data on a polymeric system
Authors: Alves N M , Mano J F , Gómez Ribelles J L
Published: August 2002

Thermally stimulated recovery (TSR) is a low frequency mechanical spectroscopy technique that allows investigation of conformational mobility in polymeric systems. In this study the effect of initial parameters chosen to perform experiments on the TSR response of a material in the thermal sampling mode is investigated. The studied experimental parameters are creep time (tσ) recovery time (tr) and window width (ΔTw); all are independently changed at one constant creep temperature. A simple model, able to describe global TSR and TS measurements, is used to evaluate the influence of each of the different parameters. The simulations are conducted for a system with a uniform distribution of activation energies and a fixed pre‐exponential factor. These simulation results are qualitatively compared with some experimental data obtained for semicrystalline poly(ethylene terephthalate) under different conditions in the glass transition region. The tendencies resulting from the influence of the studied parameters on the intensity, the position of the TS peaks and the corresponding activation energies are found to be the same for the experimental and simulated results. Only the variation of the activation energy with tσ is opposite to that observed with the modelling results; this feature is explained on the basis of structural relaxation effects.

© 2002 Society of Chemical Industry
Tensile behaviour of homogeneous ethylene copolymers
Authors: Xu Xu‐Rong , Xu Jun‐Ting , Feng Lin‐Xian
Published: August 2002

The tensile behaviour of homogeneous ethylene–butene copolymer and heterogeneous ethylene–butene copolymer has been compared in uniaxial tension. The homogeneous copolymer exhibits a more marked double yield behaviour. Composition distribution and heat treatment greatly influence the double yield behaviour of ethylene copolymer. A more homogeneous composition distribution has the same effect as rising draw temperature and decreasing draw rate on the double yield behaviour of ethylene copolymers. It is found that the occurrence of the double yield phenomenon is distinguished by the difference between two yield strains. Metallocene‐based ethylene copolymer shows better tensile break properties than conventional ethylene copolymer.

© 2002 Society of Chemical Industry
Synthesis and characterization of some polyamides incorporating modified isophthalic acid units
Authors: Onciu Marioara , Rusu Elena
Published: August 2002

Some polyamides with side chains were prepared using a direct polycondensation reaction between carboxyl groups from O‐cinnamoyl‐5‐hydroxyisophthalic acid and N‐cinnamoyl‐5‐aminoisophthalic acid and various diisocyanates in the presence of 4‐dimethylaminopyridine, as catalyst, without use of condensing agents. The polymers were characterized by elemental analysis, viscosimetry, spectroscopic and thermal measurements.

© 2002 Society of Chemical Industry
Microstructure analysis of N‐vinyl‐2‐pyrrolidone/vinyl acetate copolymers by NMR spectroscopy
Authors: Brar Ajaib S , Kumar Rajeev
Published: August 2002

N‐Vinyl‐2‐pyrrolidone (V) and vinyl acetate (A) copolymers of different compositions were synthesized by free radical bulk polymerization. The copolymer composition of these copolymers was determined using quantitative 13C{1H} NMR spectra. The reactivity ratios for these comonomers were determined using the Kelen–Tudos (KT) and non‐linear least‐square error‐in‐variable (EVM) methods. The reactivity ratios calculated from the KT and EVM methods are rV = 2.86 ± 0.16, rA = 0.36 ± 0.09 and rV = 2.56, rA = 0.33, respectively. 1H, 13C{1H} and 1H–13C heteronuclear shift correlation spectroscopy (HSQC) and 1H–1H homonuclear total correlation spectroscopy (TOCSY) were used for the compositional and configurational assignments of V/A copolymers. The 13C distortionless enhancement by polarization transfer (DEPT) technique was used to resolve the methine, methylene and methyl resonance signals in the V/A copolymers.

© 2002 Society of Chemical Industry
Effect of isomerization on thermal behaviour of bisitaconimides
Authors: Solanki Anjali , Choudhary Veena , Varma I K
Published: August 2002

The effect of isomerization of N,N′‐bisitaconimido‐4,4′‐diphenyl ether to the corresponding biscitraconimide on the curing characteristics and thermal stability of cured resins is described. Resins having bisitaconimide:biscitraconimide ratios of 23:77–93:7 were prepared by reacting 4,4′‐diaminodiphenyl ether with itaconic anhydride in solvents of different polarities and under different reaction conditions. Resins containing a higher proportion of citraconimide had a lower melting point (191 vs 208 °C). The curing exotherm was observed immediately after melting in all the resins and exothermic peak temperature reduced with increase in citraconimide content. Resins having a higher proportion of citraconimide on isothermal curing (200 °C, 2 h) and subsequent heating in nitrogen atmosphere degraded at a slightly lower temperature. However, the char yield at 800 °C did not show any systematic dependence on citraconimide content.

© 2002 Society of Chemical Industry
Gel formation in atom transfer radical polymerization of 2‐(N,N‐dimethylamino)ethyl methacrylate and ethylene glycol dimethacrylate
Authors: Jiang Chengfa , Shen Youqing , Zhu Shiping , Hunkeler David
Published: August 2002

Copolymers of 2‐(N,N‐dimethylamino)ethyl methacrylate (DMAEMA) and ethylene glycol dimethacrylate (EGDMA) were synthesized via atom transfer radical polymerization using ethyl 2‐bromoisobutyrate as the initiator, Cu(I)Br as the catalyst, and 1,1,4,7,10,10‐hexamethyltriethylene tetramine as the ligand. At low crosslinker levels, the polymerizations followed the first‐order kinetics. However, when the crosslinker level was above 10 mol %, the ln([M]0/[M]) versus time curves showed deceleration at medium conversions because of the higher reactivity of EGDMA than that of DMAEMA. An acceleration at high conversions was also observed and probably caused by the diffusion limitations of catalyst/ligand complex in the polymer network. The hydrogels were characterized by swelling experiments, and the sol polymers were characterized by the size exclusion chromatographic technique to determine the number‐average molecular weight and polydispersity. The gel data were analyzed and, via a comparison to Flory's gelation theory, found to be more homogeneous than similar hydrogels prepared by conventional free‐radical polymerization methods. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3780–3788, 2001
Amine–quinone polyimides
Authors: Han Mijeong , Nikles David E.
Published: August 2002

Two dianiline monomers were prepared by the reaction of either 4,4′‐methylenedianiline or 4,4′‐oxydianiline with 1,4‐benzoquinone. These monomers were used to synthesize a series of amine–quinone polyimides by condensation with either 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride or 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride to make the corresponding polyamic acid. The polyamic acids were converted to the polyimides by thermal imidization at 290 °C. The amine–quinone polyimides gave freestanding films with tensile strengths in the range of 90 to 150 MPa and Young's moduli of 0.9 to 1.5 GPa. The thermal decomposition temperature under nitrogen was 440 to 480 °C and the glass‐transition temperature was in the range of 280 to 310 °C. The amine–quinone polyimides had the excellent thermal and mechanical properties that one expects for polyimides. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4044–4049, 2001
Synthesis and characterization of novel crosslinkable polymers with a nonlinear optical chromophore as a pendant group
Authors: Jin Sung‐Ho , Kim Sung‐Hyun , Gal Yeong‐Soon
Published: August 2002

New crosslinkable polymers with a nonlinear optical (NLO) active chromophore as a pendant group were synthesized by condensation chain polymerization via palladium‐catalyzed carbon–carbon coupling reactions. The polymerization yields were almost quantitative between the diiodobenzene (DIB) and diethyldipropargyl malonate (DEDPM) or 4‐(dimethylamino)‐4′‐(6‐dipropargylacetoxypropylsulfonyl)stilbene (DASS‐6) monomers. To improve the molecular weight and mechanical properties of the NLO active polymer, we carried out the copolymerization with DIB and DASS‐6 with various feed ratios of DEDPM. The resulting polymers were soluble in organic solvents and spun‐cast onto indium tin oxide‐coated glass substrates to make thin films. The molecular structures of the resulting polymers were characterized with various instrumental methods to confirm the carbon–carbon coupling reactions between the DIB and diacetylene monomers. The absorption of the ultraviolet–visible spectrum of the resulting polymers was drastically reduced after thermal curing at 160 °C because of the crosslinking of the reactive acetylene group in the polymer backbone. The electrooptic coefficient (r33) measured at 1.3 μm ranged from 7 to 15 pm/V. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4025–4034, 2001
Aqueous photopolymerization with visible‐light photoinitiators: Acrylamide polymerization photoinitiated with a phenoxazine dye/amine system
Authors: Villegas L. , Encinas M. V. , Rufs A. M. , Bueno C. , Bertolotti S. , Previtali C. M.
Published: August 2002

We studied the photoinduced electron‐transfer polymerization of acrylamide with, as a visible‐light initiator, the heterocycle‐N‐oxide resazurin in the presence of triethanolamine. The irradiation of resazurin produces resorufin, which also absorbs in the visible region. Both phenoxazine dyes in the presence of the amine are efficient photoinitiators of acrylamide polymerization in an aqueous medium. The polymerization rates were measured at several amine concentrations. These values increase with the amine concentration, reaching a maximum value; further amine addition slightly decreases the polymerization rate. Time‐resolved photolysis studies of the dyes were carried out under the polymerization conditions. The quenching of the dye excited states by the amine was analyzed with static‐fluorescence and laser‐flash photolysis. These data were used for fitting curves of the polymerization rate versus the amine concentration, and it was concluded that the interaction of triplet excited dyes with the amine leads to acrylamide polymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4074–4082, 2001
Synthesis of linear and starlike polymers from poly(propylene glycol) methacrylate using controlled radical polymerization
Authors: Shemper Bianca S. , Acar A. Ersin , Mathias Lon J.
Published: August 2002

The copper‐catalyzed atom transfer radical polymerization (ATRP) of poly(propylene glycol) methacrylate (PPGM) in solution to produce linear and starlike polymers is reported, using methylethyl ketone as the solvent and a temperature of 80 °C. The ATRP system used was efficient for polymerization of the functionalized monomer without protecting hydroxyl end groups of monomer. The polymerizations were consistent with “living” or controlled processes, as revealed by the linear evolution of molecular weight with conversion. Increasing the [M]0:[I]0 ratio resulted in increasing molecular weights, whereas the polydispersity indices remained low (Mw/Mn < 1.4) even at high conversion. Decreasing the [CuBr]0:[I]0 ratio resulted in lower conversions, slightly larger polydispersities, and decreased molecular weights, likely resulting from a lower initiation efficiency. Polymers were characterized by 1H and 13C NMR; molecular weights of polymers with low degrees of polymerization were estimated by end‐group analysis from 13C NMR spectra obtained using distortionless enhancement by polarization transfer and the gated decoupling techniques. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 334–343, 2002
Synthesis and biodegradation of poly(ester amide)s containing amino acid residues: The effect of the stereoisomeric composition of L‐ and D‐phenylalanines on the enzymatic degradation of the polymers
Authors: Fan Yujiang , Kobayashi Masami , Kise Hideo
Published: August 2002

Biodegradable poly(ester amide)s that contained phenylalanine residues in the main chains were synthesized by the polycondensation of di‐p‐nitrophenyl sebacate and phenylalanine 2‐aminoethyl ester. The stereoisomeric composition (L/D ratio) of the phenylalanine residue in the monomer did not affect the yield and molecular weight of the polymer much. From the optical rotations of the polymers, it was found that the L/D ratio of the phenylalanine residue in the polymer was almost equal to the L/D ratio of the phenylalanine residue in the monomer. The biodegradability of the poly(ester amide)s was studied in aqueous solutions with proteases as catalysts. The polymer with 100% L‐phenylalanine residue was effectively degraded by α‐chymotrypsin or subtilisins. However, the replacement of 10% L‐phenylalanine with D‐isomer resulted in a dramatic decrease in degradability. The polymers with less than 30% L‐isomer were hardly degraded by the enzymes. Gel permeation chromatography studies suggested that the solubility of the degradation products in water greatly affected the rate and extent of biodegradation. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 385–392, 2002
Novel tricontinuous hydrophilic–lipophilic–oxyphilic membranes: Synthesis and characterization
Authors: Kurian Pious , Kennedy Joseph P.
Published: August 2002

Novel tricontinuous membranes consisting of well‐defined hydrophilic poly(ethylene glycol) (PEG) and lipophilic polyisobutylene (PIB) segments crosslinked by oxyphilic poly(pentamethylcyclopentasiloxane) (PD5) domains have been synthesized and characterized. Tricontinuity arises because the three membrane constituents—PEG, PIB, and PD5—are mutually incompatible and give rise to three independent cocontinuous phases (channels). The continuous PEG segments impart swelling in water (hydrogel character), the rubbery PIB moieties provide strength, and the PD5 domains provide crosslinking and enhanced O2 permeability. The synthesis involves the random cohydrosilation of various lengths (number‐average molecular weights) of α,ω‐diallyl‐PEG and α,ω‐diallyl‐PIB segments by pentamethylcyclopentasiloxane (D5H) followed by water‐mediated oxidation of the SiH groups of the D5H to SiOH groups, which immediately polycondense to PD5 domains. Membranes containing about equal amounts of PEG, PIB, and PD5 give rise to tricontinuous morphologies that allow the simultaneous permeation of water, heptane, and oxygen via three cocontinuous channels. The number‐average molecular weight of the PEG segment, that is, the number‐average molecular weight of the hydrophilic segment between two PD5 crosslink sites, determines the dimensions (pore sizes) of the channels through which water can permeate. A method has been developed for studying the oxygen permeability of membranes. The microarchitecture of the membranes has been investigated with selective swelling experiments and Fourier transform infrared spectroscopy, their mechanical properties have been examined in the water‐swollen state with Instron measurements, and their bulk morphologies and thermal degradation have been determined with differential scanning calorimetry and thermogravimetric analysis, respectively. The findings have been interpreted in terms of phase‐separated PEG, PIB, and PD5 microdomains. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1209–1217, 2002
Synthesis and properties of poly(ether imide)s based on a benzonorbornane bis(ether anhydride)
Authors: Hsiao Sheng‐Huei , Huang Tai‐Lin
Published: August 2002

A novel bis(ether anhydride) monomer, 3,6‐bis(3,4‐dicarboxyphenoxy)benzonorbornane dianhydride, was synthesized from the nitro displacement of 4‐nitrophthalonitrile with 3,6‐dihydroxybenzonorbornane in the presence of potassium carbonate, followed by the alkaline hydrolysis of the intermediate bis(ether dinitrile) and the cyclodehydration of the resulting bis(ether diacid). A series of poly(ether imide)s bearing pendant norbornane groups were prepared from the bis(ether anhydride) with various aromatic diamines via a conventional two‐stage process that included ring‐opening polyaddition to form the poly(amic acid)s followed by thermal imidization to the poly(ether imide)s. The inherent viscosities of the poly(amic acid) precursors were 0.81–1.81 dL/g. The poly(ether imide) with m‐phenylenediamine as a diamine showed good organosolubility. Most of the cast poly(ether imide) films have had high tensile strengths and moduli. The glass‐transition temperatures of these poly(ether imide)s, except for those from rigid p‐phenylenediamine and benzidine, were recorded between 211 and 246 °C by differential scanning calorimetry. The softening temperatures of all the poly(ether imide) films stayed within 210–330 °C according to thermomechanical analysis. No polymers showed significant decomposition before 500 °C in a nitrogen or air atmosphere. A comparative study of the properties with the corresponding poly(ether imide)s without pendant substituents was also made. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1712–1725, 2002
Synthesis, characterization, and in vitro degradation of liquid‐crystalline terpolyesters of 4‐hydroxyphenylacetic acid/3‐(4‐hydroxyphenyl)propionic acid with terephthalic acid and 2,6‐naphthalene diol
Authors: Prasad V. S. , Pillai C. K. S.
Published: August 2002

Melt‐processable liquid‐crystalline terpolyesters of 4‐hydroxyphenylacetic acid (HPAA) and 3‐(4‐hydroxyphenyl)propionic acid (HPPA) with terephthalic acid and 2,6‐naphthalene diol were synthesized by one‐step acidolysis melt polycondensation followed by postpolymerization and were characterized with viscosity studies, Fourier transform infrared (FTIR) and NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarized light microscopy, and wide‐angle X‐ray diffraction. The melting behaviors and liquid‐crystalline transition temperatures of the terpolyesters were dependent on the composition of the HPAA/HPPA content. The transition temperatures of the polyesters could be effectively reduced by the introduction of an even number of built‐in short methylene spacers in combination with the 2,6‐naphthalene offset structure. A terpolyester with an HPPA content of 33% (NTP33) showed optimum properties for the glass‐transition temperature, around 71 °C, and the melting temperature, near 240 °C, with a Schlieren nematic texture. The polymer showed excellent flow behavior in a Brabender plasticorder. It was also thermally stable up to 400 °C. NTP33 showed 2.5% in vitro hydrolytic degradation in buffer solutions of pH 10 at 60 °C after 540 h. Considerable enzymatic degradation was also observed with porcine pancreas lipase/buffer solutions in comparison with Candida rugosa lipase after 60 days. The degradation was also followed with FTIR, DSC, and TGA. Apart from the temperature and pH of the buffer solution, several structural parameters, such as the aromatic content, crystallinity percentage, and composition of the polymer, affected the degradation behavior. FTIR studies indicated the involvement of chain scission during degradation. Scanning electron microscopy studies further showed that surface erosion also played a major role in the degradation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1845–1857, 2002
MALDI‐TOF‐MS analysis of living cationic polymerization of vinyl ethers. II. Living nature of growing end and side reactions
Authors: Katayama Hiroshi , Kamigaito Masami , Sawamoto Mitsuo
Published: August 2002

Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analysis revealed that the HCl–vinyl ether adduct/SnCl4/n‐Bu4NCl initiating system induced living cationic polymerization of isobutyl vinyl ether in CH2Cl2 at −78 °C, that is, the well‐resolved spectra demonstrated that the produced polymers consist of only one series of polymers carrying one initiator fragment at the α end and one methoxy group originated from quenching with methanol at the ω end. The polymer molecular weight as well as the terminal structure were unchanged even when the reaction mixtures were kept unquenched at −78 °C for an interval of more than five times longer than the reaction period after complete consumption of monomer, which indicates the long lifetime of the living end even under such starved conditions. In contrast, the polymers obtained at a higher temperature, −15 °C, showed an additional minor series of polymers formed via proton initiation, originating from adventitious water. Under the starved conditions, other side reactions occurred to generate minor series of polymers with an aldehyde ω end or a diisobutyl acetal ω end. Rather surprisingly, however, unsaturated CC end groups were not detected, which means the absence of β‐proton elimination under these conditions. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1249–1257, 2001
Hydrazone initiators for vinyl polymerizations
Authors: Wolf Richard A. , Warakomski John M. , Staples Thomas L. , Fazio Michael J.
Published: August 2002

A series of hydrazones were prepared and tested for their ability to act as free‐radical initiators for vinyl monomers. The most active initiators were the tertiary butyl hydrazones of aromatic, aliphatic ketones. The most reactive vinyl monomers were acrylate‐type monomers, with methacrylate‐type monomers being somewhat less reactive. When the most reactive hydrazone initiators, such as compound 1, were added to ambient‐temperature solutions of acrylate monomers, such as aqueous sodium acrylate or aqueous acrylamide, polymerizations to hard gels occured within 1 min. In some cases of vinyl polymerizations, these hydrazone initiators can act as low‐temperature alternatives to redox initiators. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1391–1402, 2001
Synthesis, characterization, and crosslinking of novel stars comprising eight poly(isobutylene‐azeotropic‐styrene) copolymer arms with allyl or hydroxyl termini. II. Stars of eight isobutylene/styrene azeotropic copolymer arms emanating from a calix[8]arene core
Authors: Hull Diana L. , Kennedy Joseph P.
Published: August 2002

Our objective was the precision synthesis of novel stars consisting of a well‐defined calix[8]arene core out of which radiate eight poly(isobutylene‐aze‐styrene) [P(IB‐aze‐St)] arms fitted with crosslinkable end groups. We reached our objective by preparing the octafunctional calixarene derivative C[8]OCH3, inducing the living azeotropic copolymerization of IB/St charges with the C[8]OCH3/BCl3·TiCl4 initiating system, and end‐quenching living IB/St copolymerizations with allyltrimethylsilane. With this strategy, we obtained stars C[8][P(IB‐aze‐St)CH2CHCH2]8 of various molecular weights. The number of CH2CHCH2 termini of the arms was 8.0 ± 0.2 by quantitative 1H NMR analysis. The eight allyl termini were quantitatively converted to CH2CH2CH2OH termini by hydroboration/oxidation. To confirm that the latter second‐generation stars possessed eight primary alcohol end groups, we quantitatively converted the CH2OH termini to OSi(CH3)3 termini, the concentration of which was quantitated by 1H NMR spectroscopy. According to this analysis, the stars contained 8.0 ± 0.3 hydroxyl termini. The glass‐transition temperatures of the P(IB‐aze‐St) arms increased from 59 to 65 °C as the weight‐average molecular weights of the arms increased from about 2500 to about 4300 g/mol, respectively. The α and K constants of the Mark–Houwink–Sakurada relationship and the intrinsic viscosity of a representative allyl‐telechelic star were determined and compared with a linear azeotropic IB/St copolymer of similar molecular weight. The crosslinking of C[8][P(IB‐aze‐St)CH2CH2CH2OH]8 stars with 4,4′‐methylene bis(phenyl) diisocyanate and 2,4‐tolylene diisocyanate in various solvents afforded tightly crosslinked films of potential interest for scratch‐resistant coatings, mar‐resistant coatings, or both. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1525–1532, 2001
Using polymers to control substrate, ligand, or catalyst solubility
Authors: Bergbreiter David E.
Published: August 2002

The attributes and design of soluble polymer supports for catalysis and synthesis are discussed. By manipulating polymer structure, polymer supports can be prepared so that the solubility of an attached reagent, substrate, or ligand is affected by heating, cooling, pH, or solvent identity. Supports with such engineered solubility are useful both in organic synthesis and catalysis. They can be used as purification handles in organic synthesis as a way to recover catalysts, as a way to turn reactions on or off, and more generally, as a handle for separations. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2351–2363, 2001
Photoinitiated polymerization of methacrylic monomers in a polybutadiene matrix (PB): Kinetic, mechanistic, and structural aspects
Authors: Mateo J. L. , Calvo M. , Bosch P.
Published: August 2002

The kinetics and mechanism of the photoinitiated polymerization of tetrafunctional and difunctional methacrylic monomers [1,6‐hexanediol dimethacylate (HDDMA) and 2‐ethylhexyl methacrylate (EHMA)] in a polybutadiene matrix (PB) have been studied. The maximum double‐bond conversion, the maximum polymerization rate, the intrinsic reactivity, and the kinetic constants for propagation and termination have been calculated. Unlike the behavior followed by the SBS‐HDDMA and PS‐HDDMA systems, where a reaction‐diffusion mechanism occurs from the start of the polymerization at low monomer concentrations (<30–40%), in the PB‐HDDMA system the reaction diffusion controls the termination process only after approximately 10% conversion is reached, as for the bulk polymerization of polyfunctional methacrylic monomers. Before reaching 10% conversion the behavior observed can be better explained by a combination of segmental diffusion‐controlled (autoaccelerated) and reaction‐diffusion mechanisms. This is probably a consequence of the lower force of attraction between the monomer and the matrix and between the growing macroradical and the matrix than those corresponding to the other systems mentioned. For the PB‐EHMA system, the termination mechanism is principally diffusion‐controlled from the beginning of the polymerization for monomer concentrations below 30–40%, and for higher monomer concentrations, a standard termination mechanism takes place (kt ≈ 106) at low double‐bond conversions, which is diffusion‐controlled for high conversions (>40%). For PB‐HDDMA and PB‐EHMA systems, crosslinked polymerized products are obtained as a result of the participation of the double bonds of the matrix in the polymerization process. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2444–2453, 2001
Emulsion polymerization of methyl methacrylate in the presence of novel addition–fragmentation chain‐transfer reactive surfactant (transurf)
Authors: Monteiro Michael J. , Bussels Raf , Wilkinson Terence S.
Published: August 2002

Reactive surfactants allow the surfactant molecules to become covalently bound to the particles and thus provide added stability to the colloid particles, longer shelf life, better shear resistance, and polymer particles that can be redispersed. This article reports for the first time the use of a novel addition–fragmentation chain‐transfer reactive surfactant (transurf) in ab initio emulsion polymerizations of methyl methacrylate at 70 °C. It was found that the rate was lowered and average particle diameter nearly doubled when the transurf was used as compared with the SDS experiments (control). In addition the molecular weight distribution was very broad but had a lower Mn than observed in the sodium dodecyl sulfate experiment. Unfortunately because of the formation of many water‐soluble oligomers, the amount of transurf incorporated could not be obtained accurately. However, it was estimated theoretically that only a very small amount of transurf would be consumed, but for an alternative method to increase the incorporation of transurf into the particles, the ratio of monomer to transurf must be kept as low as possible. The best way to achieve this would be to carry the experiments out under starved‐feed conditions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2813–2820, 2001
Synthesis and characterization of soluble polyimides derived from [1,1′;4′,1″]terphenyl‐2′,5′‐diol and biphenyl‐2,5‐diol
Authors: Xu Jianwei , He Chaobin , Chung T.‐S.
Published: August 2002

Two series of polyimides based on laterally attached p‐terphenyl and biphenyl groups were synthesized. The solubility and thermal properties were studied using DSC, thermogravimetric analysis, and the solubility test. These polymers exhibited good thermal stability and excellent solubility. The high solubility for both polymer series was attributed to the non‐coplanarity of diamine monomers and the use of fluorinated dianhydride, whereas the slightly better solubility for polymers based on p‐terphenyl was attributed to further weakening of interchain interaction of the polymers. Both polymer series exhibited glass‐transition temperatures (Tg's) in the range of 244–272 °C. The Tg's of polymers containing laterally attached p‐terphenyls were higher than those of their counterparts containing biphenyls by 5–17 °C. This was attributed to the formation of an interdigitated structure that hinders the segmental movement of polymer chains. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2998–3007, 2001
Synthesis, characterization, and in vitro degradation of thermotropic polyesters and copolyesters based on terephthalic acid, 3‐(4‐hydroxyphenyl)propionic acid, and glycols
Authors: Nagata Minoru , Nakae Masayuki
Published: August 2002

A new series of thermotropic liquid‐crystalline (LC) polyesters were prepared from a diacyl chloride derivative of 4,4′‐(terephthaloyldioxy)‐di‐4‐phenylpropionic acid (PTP) and glycols with a different number of methylene groups (n) [HO(CH2)n OH, n = 6–10, 12] by high‐temperature solution polycondensation in diphenyl oxide. PTP6/10 and PTP6/hydroquinone (H) LC copolyesters were also prepared according to a similar procedure. The chemical structure, LC, phase‐transition behaviors, thermal stability, and solubility were characterized by elemental analysis, Fourier transform infrared spectroscopy, 1H and 13C NMR spectra, differential scanning calorimetry (DSC), thermogravimetric analysis, and a polarizing light microscope. The melting and isotropization temperatures decreased in a zigzag manner as the number of n increased. All of the polyesters formed a nematic phase with the exception of PTP8. The temperature ranges of the mesophase (ΔT) were much wider for the polyesters with an odd number of n's than those with an even number. ΔT increased markedly for the PTP6/10 and PTP6/H copolyesters. The in vitro degradations of the polymers were ascertained by enzymatic hydrolysis and alkaline hydrolysis. The model compound, PTP dihexylester, was synthesized and found to be degraded into terephthalic acid, 3‐(4‐hydroxyphenyl)propionic acid, and 1‐hexanol by Rhizopus delemar lipase, but PTPn homopolyesters and PTP6/10 and PTP6/H copolyesters were resistant to Rhizopus delemar hydrolysis. They were degradable in a sodium hydroxide buffer solution of pH 12 at 60 °C, depending on the number of n's and the copolymer composition. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3043–3051, 2001
Ultrasonically initiated emulsion polymerization of methyl methacrylate
Authors: Liao Yongqin , Wang Qi , Xia Hesheng , Xu Xi , Baxter Steven M. , Slone Robert V. , Wu Shuguang , Swift Graham , Westmoreland David G.
Published: August 2002

The ultrasonically initiated emulsion polymerization of methyl methacrylate (MMA) was investigated. Experimental results show that sodium dodecyl sulfonate (SDS) surfactant plays a very important role in obtaining a high polymer yield, because in the absence of SDS, monomer conversion is near zero. Thus, the surfactant serves as an initiator and as interfacial modifier in this system (MMA/H2O), and the monomer conversion increases significantly with increasing SDS concentration. An increase in the reactor temperature also leads to an increase in the monomer conversion. An appropriate increase in the N2 purging rate also leads to higher conversion. The conversion of MMA decreases with increasing monomer concentration because of the higher viscosity of the system. With the experimental results, optimized reaction conditions were obtained. Accordingly, a high monomer conversion of about 67% and a high molecular weight of several millions can be obtained in a period of about 30 min. Furthermore, transmission electron micrographs show that the latex particles prepared are nanosized, indicating a promising technique for preparing nanoscale latex particles with a small amount of surfactant. In conclusion, a promising technique for ultrasonically initiated emulsion polymerization has been successfully performed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3356–3364, 2001
Synthesis of phosphate‐pendant polymers and their application to thermally latent polymeric initiators
Authors: Kim Moon Suk , Sanda Fumio , Endo Takeshi
Published: August 2002

A novel phosphate monomer, O‐p‐(methacryloyloxymethyl)benzyl O,O‐diethyl phosphate (MDP) was synthesized by the reaction of diethyl phosphorochloridate with 1,4‐benzenedimethanol, followed by the reaction with methacryloyl chloride in the presence of triethylamine. The radical polymerization of MDP and copolymerization with methyl methacrylate were carried out in the presence of 2,2′‐azobisisobutyronitrile (3 mol %) in dimethylacetamide at 60 °C for 20 h to afford phosphate‐pendant polymers. The polymerization of glycidyl phenyl ether (GPE) was carried out with the phosphate‐pendant polymer as an initiator in the presence of ZnCl2. The polymerization did not proceed below 90 °C but rapidly proceeded above 90 °C to afford polyGPE. The phosphate‐pendant polymer served as a good thermally latent polymeric initiator. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3365–3370, 2001