bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and properties of new segmented block poly(urethane‐urea)s containing phosphatidylcholine analogues and polybutadienes
Authors: Chen Tian‐Ming , Wang Yan‐Feng , Li Yu‐Jun , Kitamura Masaya , Nakaya Tadao
Published: April 2003

New hydrophobic‐hydrophilic microphase‐separated block segmented copoly(urethane‐urea)s were synthesized by introducing hydrophobic polybutadienes as the soft segments and 4,4′‐methylenediphenyl diisocyanate, hexamethylene diisocyanate, ethylenediamine, and a hydrophilic phosphatidylcholine analogue as the hard segments in the backbones of these polymers. The results of ATR‐IR and XPS show the coexistence of phosphatidylcholine analogues and polybutadienes on the surface of cast films of the synthesized poly(urethane‐urea)s. Furthermore, TEM cross sectional observation of the cast film PBDP‐1370 indicates that it possesses a hydrophilic‐hydrophobic microphase‐separated domain structure.
Reversible photodimerisation of ω‐anthrylpolystyrenes
Authors: Coursan Magali , Desvergne Jean Pierre , Deffieux Alain
Published: April 2003

The preparation of polystyrene with controlled molar masses and narrow dispersity endcapped with an anthrylmethyl ether group, as well as the study of their photophysical properties, are described. Under irradiation at 336 nm dimerisation of the polystyrene chains is observed. This process results from the formation of a symmetrical head‐to‐tail photodimer between two anthryl end groups. When irradiated at lower wavelength (λ = 228 nm), the original ω‐anthrylpolystyrene chains are quantitatively restored. These dimerisation/dissociation cycles can be conducted more than ten times without any detectable degradation of the photosensitive polymer. The fluorescence emission quantum yield and fluorescence lifetime of the ω‐anthryl moieties and the quantum yield of the dimerisation and of the reverse process have been measured.
Comparison of thermal and microwave‐activated polymerization of ε‐caprolactone with titanium tetrabutylate as catalyst
Authors: Albert Philipp , Warth Holger , Mülhaupt Rolf , Janda Ralf
Published: April 2003

Thermal and microwave‐activated ring‐opening polymerization at 180°C in the presence of titanium tetrabutylate at different ε‐caprolactone/titanium tetrabutylate molar ratios were compared. A special equipment was developed to control polymerization in the microwave field and to simultaneously monitor viscosity build‐up as well as changes in microwave powers corresponding to input, reflection and transmission. Conversion, measured by means of viscosity build‐up, and number‐average molecular weight of poly(ε‐caprolactone) were similar for both processes and did not indicate advantages relating to the use of microwave irradiation.
Hydroxytelechelic polybutadiene, 14. Gelation of a radically obtained hydroxytelechelic polybutadiene with 4,4′‐methylenedi(phenyl isocyanate)
Authors: Allard‐Breton Bétrice , Audenaert Marc , Pham Quang Tho
Published: April 2003

A new commercial radically obtained hydroxytelechelic polybutadiene (HTPB‐A) was examined by 1H NMR at 500 MHz, and a corrected interpretation of the complex proton methylene resonance of the vinyl‐type primary alcohol was done. The weight‐average hydroxyl functionality F̄w (OH) was determined by using critical conversions at gel points of the (HTPB‐A + diisocyanate) systems, on the one hand, and swelling at equilibrium on the other. The functionality polydispersity index of HTPB‐A is close to unity.
Raman spectroscopic study on water in aqueous gelatin gels and sols
Authors: Tsukida Noriaki , Maeda Yasushi , Kitano Hiromi
Published: April 2003

A Raman spectroscopic study on property changes of water in aqueous gelatin media was carried out. The state of water in gelatin gels and sols at various temperatures and concentrations was studied in connection with the conformation of polymer chains. When gelatin with a low molecular weight was used, there was no gel‐sol transition, and the structure of water observed by Raman spectroscopy was not significantly affected by the presence of gelatin. When gelatin with a high molecular weight was used, on the other hand, the structure of water strongly depended on the concentration of gelatin both in the gel and the sol state. A contribution of small spaces surrounded by entangled gelatin chains (which exist both in high concentration gels and sols) to the perturbation of the structure of incorporated water was suggested. It was also found that, at 60°C, gelatin chains in the low concentration region induced an enhancement of structured water. This is the first finding that water soluble polymers at high temperature induce the network structure of water.
Temperature‐responsive polymer microspheres prepared with a macroinitiator
Authors: Kitano Hiromi , Kawabata Junko
Published: April 2003

A macroinitiator was prepared by coupling of the disuccinimidyl ester of 4,4′‐azobis(cyanovaleric acid) with poly(N‐isopropylacrylamide) (PIPA) with terminal amino group. Styrene and divinylbenzene were copolymerized with the initiator in the presence of sodium dodecylsulfate. The polymer microspheres obtained have PIPA chains on their surfaces, and the stability of a suspension of the microspheres in the presence of electrolyte is largely influenced by the temperature, whereas that of microspheres without PIPA chains is not. The usefulness of macroinitiators to prepare various polymer materials which are responsive to external stimuli was strongly emphasized.
Chromatographic investigations of polyacetals in the critical range of liquid chromatography, 1. Analysis of 9‐anthrylmethyl‐terminated poly(1,3,6‐trioxacyclooctane)s
Authors: Gancheva Valeria B. , Vladimirov Nikolai G. , Velichkova Rumiana S.
Published: April 2003

Bifunctional poly(1,3,6‐trioxacyclooctane)s were obtained with (CF3SO2)2O as initiator in cationic ring‐opening polymerization via active chain‐end mechanism. To achieve a precise characterization of poly(1,3,6‐trioxacyclooctane) fractions with respect to molecular weight and end functionality, induced termination with ultraviolet (UV)‐active 9‐anthrylmethyl derivatives (ACH2—) was performed. This group improves the detection of the end‐functions and the separation into functionality fractions as it changes the hydrophilic‐hydrophobic balance of the macromolecules. With high‐performance liquid chromatography (HPLC) at the critical point of adsorption combined with photo‐diodearray detection and gel‐permeation chromatography (GPC) characterization of the molecular weight and the functionality distributions of the products was realized. Semipreparative separation followed by GPC and 1H nuclear‐magnetic resonance (NMR) analysis of the fractions was used to determine their molecular weight distribution, average structure and type of the end groups. These analyses confirmed the correctness of the results from HPLC, based on elution at “critical conditions” of oligomers fitted with UV‐active groups. This method is suitable for the separation of poly(1,3,6‐trioxacyclooctane)s with molecular weights less than 20000.
Protection and polymerization of functional monomers, 26. Synthesis of well‐defined poly[4‐(3′‐butynyl)styrene] by means of anionic polymerization of 4‐(4′‐trimethylsilyl‐3′‐butynyl)styrene
Authors: Ishizone Takashi , Hirao Akira , Nakahama Seiichi , Tsuda Katsuyuki
Published: April 2003

Anionic polymerization of 4‐(4′‐trimethylsilyl‐3′‐butynyl)styrene (2) was carried out in THF at −78°C for 0.5 h with oligo(α‐methylstyryl)lithium, ‐dilithium, and ‐dipotassium. Poly(2)s possessing predicted molecular weights and narrow molecular weight distributions (M̄w/M̄n < 1.11) were quantitatively obtained in all cases. By sequential anionic copolymerization of 2 and styrene, novel block copolymers, polystyrene‐block‐poly(2) starting either from living polystyrene or living poly(2), were synthesized. After completion of the polymerization, there occurred some gradual deactivation of the propagating carbanion of poly(2) at −78°C. This deactivation reaction could be almost completely suppressed at −95°C. The deprotection of poly(2) was performed by treating with Bu4NF in THF at 0°C for 1 h. The trimethylsilyl protecting group of poly(2) was completely removed to afford a poly[4‐(3′‐butynyl)styrene] of a controlled molecular structure.
Sequence change of poly(N‐acylurethane)s based on transesterification
Authors: Kanamaru Masami , Takata Toshikazu , Endo Takeshi
Published: April 2003

Modification of poly(N‐acylurethane)s (3a–c) by transesterification with hexyl alcohol and 2‐dodecyl‐1,3‐propanediol (2a) under mild conditions was studied. 3 were prepared by polyaddition of corresponding bis(N‐acylisocyanate)s and diols under mild conditions in good yields. Reaction of poly(N‐acylurethane) (3a) (Mn = 22700) with two equivalents of hexyl alcohol started around 100°C to give the corresponding degradation products (Mn = 7 300, 120°C, 90 min). A mixture of poly(N‐acylurethane) (3b, Mn = 17500) with an equimolar amount of 2a was heated at 150°C under reduced pressure to remove 1,2‐propanediol. The polymer obtained was 3a of which yield and Mn were 57% and 6900, respectively. Transesterification of N‐acylurethane derived from phenol proceeded easier than that derived from alkanol. Aromatic poly(N‐acylurethane) (3c) derived from 4,4′‐dihydroxydiphenyl ether (2c) underwent a similar transesterification with 2a at lower temperature (80°C) without removal of 2c to give 3a in 43% yield. Thus, the modification of poly(N‐acylurethane)s (3) could be readily achieved by the transesterification with mono alcohols and diols under mild conditions without any catalyst.
Synthesis and enzymatic hydrolysis of polydepsipeptides with functionalized pendant groups
Authors: Ouchi Tasuro , Nozaki Tatsuya , Okamoto Yoshifumi , Shiratani Masahiro , Ohya Yuichi
Published: April 2003

Water‐soluble polydepsipeptides with functionalized side‐chain groups, i.e., alternating copolymers, consisting of glycolic acid (Glc) and L‐lysine (L‐Lys), L‐aspartic acid (L‐Asp) or L‐glutamic acid (L‐Glu) residues as α‐hydroxy acid and α‐amino acid residues, respectively, were synthesized, and their biodegradation behavior was investigated. Three kinds of polydepsipeptides, poly(Glc‐alt‐Lys), poly(Glc‐alt‐Asp) and poly(Glc‐alt‐Glu), were synthesized by means of ring‐opening polymerization of the corresponding cyclodepsipeptides and subsequent deprotection of benzyl and benzyloxycarbonyl groups. In order to estimate the main‐chain cleavage behavior of polydepsipeptides with functionalized side‐chain groups, the hydrolysis behavior of the obtained water‐soluble polydepsipeptides was first investigated in phosphate buffer solution with or without an enzyme in vitro.
Determination of transfer constants of non‐ionic thiolended surfactants (transurfs) in styrene free‐radical polymerizations
Authors: Vidal Frédéric , Gilbert Robert G.
Published: April 2003

The transfer constants of 1‐dodecanethiol and non‐ionic thiol‐ended surfactants (transurfs) have been determined for the bulk polymerization of styrene at 70°C; these values are 19 for l‐dodecanethiol and 19 and 14 for the transurfs with 17 and 90 ethylene oxide units, respectively. Transfer constants are obtained from the high‐molecular‐weight portion of the full number molecular weight distribution.
“Liquid crystalline” thermosets from 4,4′‐bis(2,3‐epoxypropoxy)biphenyl and aromatic diamines
Authors: Mormann Werner , Bröcher Markus
Published: April 2003

Pure 4,4′‐bis(2,3‐epoxypropoxy)biphenyl (1) has been synthesized and its mesophase behaviour has been investigated. 1 forms a monotropic nematic mesophase with a virtual clearing temperature of 109°C. 1 has been cured with 2,4‐diaminotoluene (3), 4,4′‐diaminobiphenyl (4), and 4‐aminophenyl 4‐aminobenzoate (5) to investigate the possibility of formation of anisotropic networks. Virtual clearing temperatures of the diamines indicate that liquid crystalline thermosets (LCT's) might be obtained with 4 and 5. Crystallization of oligomeric products from the isotropic melt of 1 with 3 or 4, respectively, occurred on isothermal curing without formation of a mesophase, while a nematic LCT was obtained with 5.
Molecular orientation of paramagnetic metal complexes in melt‐drawn fibers of thermotropic liquid crystalline polymers
Authors: Hanabusa Kenji , Hashimoto Masami , Kimura Mutsumi , Koyama Toshiki , Shirai Hirofusa
Published: April 2003

Liquid crystalline polyesters as host polymers and paramagnetic metal complexes as guest molecules were prepared, and melt‐drawn fibers were made from their blend at mesophase temperature. The wide‐angle X‐ray diffraction patterns of the fibers indicated that the nematic or smectic phase is frozen during melt‐drawing. The molecular orientation of the metal complexes in the fibers was investigated by means of ESR. The order parameter obtained from the ESR spectra of the fibers suggests that the base of the square planar Cu(II) and pyramidal V(IV)O complex is almost completely oriented parallel to the fiber axis.
Synthesis and characterization of second‐order nonlinear optical main‐chain polyurethanes containing acceptor‐substituted carbazole units
Authors: Zhang Yadong , Wang Liming , Wada Tatsuo , Sasabe Hiroyuki
Published: April 2003

A diol monomer bearing carbazole units substituted with one acceptor group was prepred starting from 3‐formyl‐9‐(4‐hydroxybutyl)carbazole and hexamethylene bis(cyanoacetate) via Knoevenagel condensation. Main‐chain polyurethanes with acceptor‐substituted carbazole as nonlinear optical chromophores were obtained by addition polymerization of the carbazole diol monomer with various diisocyanates in tetrahydrofuran at room temperature using dibutyltin diacetate as a catalyst. These carbazole main‐chain polyurethanes were found to have glass transition temperatures in the range of 113–122°C and weight‐average molecular weights in the range of 6300–11000 g/mol. The chloroformsoluble polyurethanes could be spin‐coated into thin films with good optical quality. After poling, these films displayed reasonable second harmonic generation efficiencies. Preliminary results indicated that the polyurethanes have good thermal stability compared to analogous polymers without hydrogen bonds.
Infrared spectroscopic study of the structural change of polymethacrylonitrile following heat‐treatment and subsequent treatment with water
Authors: Nagata Akira , Ohta Koji , Iwamoto Reikichi
Published: April 2003

The infrared spectrum of polymethacrylonitrile (PMAN) exhibits noticeable change on heat‐treatment up to 240°C, the color of the sample changed from yellowish at 120°C, through yellow and red, to deep red at 210°C or above. A new structure
magnified image
was proposed as a plausible structure for the chromophore of the heat‐treated PMAN film, on the basis of comprehensive consideration of details of the spectral change in reference to the corresponding spectral change of polyacrylonitrile (PAN) and the spectra of compounds having similar structures. Subsequent treatment of the deep‐red PMAN with hot water further drastically changed the infrared spectrum, and in turn the color changed from deep red to yellowish. The spectrum of the hydrolyzed product was in complete agreement with that of the copolymer of methacrylonitrile and methacrylic acid. Thus the structure was found to be
magnified image
from infrared spectral comparison.
Thermoshrinking behavior of poly(vinylcaprolactam) gels in aqueous solution
Authors: Makhaeva Elena E. , Thanh Le Thi Minh , Starodoubtsev Sergei G. , Khokhlov Alexei R.
Published: April 2003

The swelling of newly synthesized slightly crosslinked gels of polyvinylcaprolactam (PVCa) was studied as a function of temperature. In water, PVCa gels undergo a sharp volume transition from a swollen to a collapsed state on heating. In water/alcohol mixtures, the gel first shrinks and then expands as the temperature is raised. The swelling behavior of the thermosensitive PVCa gel in surfactant solution depends on kind and concentration of the surfactant. Normally, an additional swelling of the gel is observed in the presence of ionic surfactants. Addition of the surfactant raises the collapse transition temperature of the gel. Absorption of the surfactant by the PVCa gel as a function of temperature and surfactant concentration is analysed in detail.
Thermotropic polyamides containing the benzophenone unit
Authors: Hajek Andreas , Heitz Walter , Wendling Jürgen , Wendorff Joachim H.
Published: April 2003

The synthesis and structure‐property relationship of fully aromatic homo‐ and copolyamides are described. They all contain the 3,4′‐substituted benzophenone and diphenyl ether moiety in the main chain. The synthesis of the polyamides was performed at low temperatures with silylated aromatic diamines and aromatic acid chlorides. The polymers possess good solubility in dipolar aprotic solvents. They display thermotropic liquid crystalline properties. Based on results obtained by means of polarization microscopy, X‐ray scattering, and molecular dynamics simulation a rather unusual structure is proposed. It consists of a superlattice composed alternatingly of smectic B layers and amorphous layers. The formation of smectic B layers is untypical for main‐chain LC polymers without aliphatic spacers.
Synthesis of water‐soluble biologically active phenol (or catechol) containing copolymers of N‐vinyl‐2‐pyrrolidone
Authors: Solovskij Michael V. , Denisov Victor M. , Panarin Eugenij F. , Petukhova Natalija A. , Purkina Alla V.
Published: April 2003

Water‐soluble N‐vinyl‐2‐pyrrolidone (VP) copolymers containing phenol (or catechol) groups in the side chains were synthesized by reactions of copolymers of VP and crotonic acid (CA) with p‐aminophenol and by reaction of p‐nitrophenyl ester groups containing VP‐CA copolymers with dopamine. It was established that phenol (or catechol) containing multiunit VP copolymers (which were characterized by GPC, viscometry, UV, IR and 1H NMR spectroscopy) exhibit immunostimulating activity. In addition, the phenol‐containing copolymers exhibit antitumor activity. The VP‐CA‐p‐crotonoylaminophenol terpolymer can be used as a macromolecular carrier in the synthesis of a carcinogen‐polymer antigen: a polymeric azo derivative of ß‐naphthylamine.
Acyclic diene metathesis (ADMET) polymerization using a well‐defined ruthenium based metathesis catalyst
Authors: Brzezinska Krystyna , Wolfe Patrick S. , Watson Mark D. , Wagener Kenneth B.
Published: April 2003

A series of α,ω‐dienes have been exposed to Ru(Cl2)(CHPh)(PCy3)2, [Ru] 3, metathesis catalyst under acyclic diene metathesis (ADMET) conditions, and the products were compared with those obtained previously using Schrock's well defined Mo and W alkylidenes. High molecular weight polymers can be synthesized using [Ru] 3 if lower monomer to catalyst ratios with respect to [Mo] 1 and [W] 2 are used. Monomer structure plays a role since 1,9‐decadiene produces molecular weights typical of ADMET chemistry, whereas 1,5‐hexadiene produces only oligomers. This decrease in reactivity is attributed to a manifestation of intramolecular π‐complexation of the tethered olefin in 1,5‐hexadiene polymerizations. Substituents at the 2‐position of α,ω‐dienes also affects polymerization in that only dimers can be produced from 2‐methyl‐1,5‐hexadiene, a result similar to the same reaction performed with [W] 2. Diallyl ether oligomerizes effectively in the presence of [Ru] 3 with a ratio of cyclics to oligomers comparable to results obtained with [Mo] 1 and [W] 2.
Synthesis and characterization of polyoxetanes containing 4‐cyanobiphenyl‐based side groups for nonlinear optical applications, 1. Chemical modification of poly[3,3‐bis(chloromethyl)oxetane]with sodium 4‐cyano‐4′‐biphenyl oxide
Authors: Guichard Bertrand , Noël Claudine , Reyx Danièle , Kajzar François
Published: April 2003

Two copolyethers were prepared by chemical modification of poly[3,3‐bis(chloromethyl)oxetane] with sodium 4‐cyano‐4′‐biphenyl oxide, employing the concept of having the cyanobiphenyl species serve concomitantly as both the nonlinear optical chromophore and the mesogenic moiety in the polymer. Their thermal behavior was established by means of DSC and optical microscopy. Some preliminary Corona poling experiments were performed, and the second harmonic generation coefficients d31 and d33 were measured by Maker fringe analysis. The results showed that liquid crystallinity enhances field‐induced polar ordering. The ratio d33/d31 was found to be much larger than 3, in agreement with the theoretical models for electric field poling of liquid crystalline polymers where hyperpolarizable chromophores are attached as side groups to a polymer backbone.
Conformational transitions in poly(methacrylic acid) gel/poly(ethylene glycol) complexes. Effect of the gel cross‐linking density
Authors: Karybiants Natalia S. , Philippova Olga E. , Starodoubtsev Sergei G. , Khokhlov Alexei R.
Published: April 2003

We present results on the effect of the cross‐linking density on the collapse of poly‐(methacrylic acid) gels induced by the interaction with linear poly(ethylene glycol) and on their subsequent reswelling (reentrant transition). The abruptness and the amplitude of both transitions increase with decreasing cross‐linking density of the gel. A special feature of the reswelling transition for the PMAA gel/PEG system is the existence of a wide range of PEG concentrations where both collapsed and swollen states of the gel are stable. The conditions for the existence of such a region are easier realized for slightly cross‐linked gels. The corresponding theoretical explanation is given. The swelling degree of the collapsed gels increases with increasing cross‐linking density, which is explained by the presence of a certain amount of hydrophilic PEG loops in highly cross‐linked gels.
Anionic ring‐opening polymerization of cyclodisilazanes, 1. General aspects
Authors: Bruzaud Stéphane , Soum Alain
Published: April 2003

The anionic ring‐opening polymerization of a model monomer of cyclodisilazanes 1, initiated with both organosodium and organolithium initiators, was investigated. Under specific conditions, this polymerization exhibits all the characteristics of a living process. Indeed, whatever the experimental conditions chosen, there is no evidence of back‐biting and/or transfer reactions competing with the propagation reaction. Kinetic measurements showed that this polymerization is first order with respect to the concentrations of both monmer and active centers. The absolute rate constant of propagation (kp) and the thermodynamic parameters (enthalpy and entropy) of the propagation step where calculated. On the basis of these results, a mechanism of the anionic ring‐opening polymerization of 1 is proposed.
Influence of various proton traps on the bifunctional cationic polymerization of chloroethyl vinyl ether mediated by α‐iodo ether/zinc dichloride
Authors: Bennevault Véronique , Peruch Frédéric , Deffieux Alain
Published: April 2003

The synthesis of relatively high molar mass telechelic poly(chloroethyl vinyl ether)s (PCEVE) via bifunctional initiation of the “living” cationic polymerization of CEVE was examined in the absence and in the presence of various proton traps. In the absence of a proton trap, a monofunctional initiation involving hydrogen iodide (HI), formed by partial hydrolysis of trimethylsilyl iodide (TMSI) by adventitious water, occurred concurrently to the main bifunctional process. The addition of sterically hindered aromatic amines leads to complete inhibition of the polymerization due to the formation of a complex between the aromatic amines and ZnCl2. In the presence of trialkylaluminium as HI trapping agent, monofunctional initiation is totally suppressed and a clean bifunctional polymerization takes place. Telechelic PCEVE of DPn up to 300 with narrow molar mass distribution were synthesized. However, in the presence of these additives, a slow ligand exchange between AIR3 and ZnCl2 takes place, decreasing the rate of polymerization. For polymers with high DPn (>300), the increasing amount of trialkylaluminium required to totally suppress the formation of monofunctional polymer results in a chain coupling process during the deactivation step. This reaction limits the clean synthesis of high molar mass bifunctional PCEVE.
End‐group characterization of poly(methylphenylsilane) by alkali metal salts doped MALDI‐TOF mass spectra
Authors: Montaudo Giorgio , Montaudo Maurizio S. , Puglisi Concetto , Samperi Filippo , Sepulchre Maurice
Published: April 2003

The end groups of a sample of poly(methylphenylsilane) (PMPS) obtained by the Wurtz coupling reaction of diorganodichlorosilane were characterized by MALDI‐TOF mass spectrometry. Three fractions were obtained by fractionation of a PMPS sample with methanol, in order to get information on the distribution of end groups as a function of the molecular weight. The MALDI mass spectra of these fractions showed well‐resolved signals up to 2500 Da corresponding to open chain oligomers of PMPS bearing four different types of end groups: Si(CH3)3, OSi(CH3)3, OCH3, H. Six different types of linear oligomers were identified together with a sizeable amount of cyclic oligomers, most likely generated during the polymerization step. The problem of isobar mass series in the MALDI spectra due to clusters of oligomers with Li+, Na+, K+ was solved by comparing the MALDI spectra of PMPS fractions with and without the addition of a specific alkaline salt (KCl or Nal) to the solution containing the sample and matrix. The intensity of the oligomer clusters with the specific cation were enhanced with respect to the others. The mass shifts observed in the MALDI‐TOF doped spectra with respect to the undoped ones allowed the unambiguous assignments of the isobar peaks corresponding to PMPS oligomers.
Polyanhydrides, 7. Soluble polyanhydrides derived from isophthalic acid, 4‐hydroxybenzoic acid and various diphenols
Authors: Kricheldorf Hans R. , Jürgens Claas
Published: April 2003

One series of poly(ester‐anhydride)s, PEAs, was prepared by polycondensation of isophthaloyl chloride with mixtures of silylated 4‐hydroxybenzoic acid and various dihydroxy‐substituted naphthalenes. Most of these PEAs are semicrystalline materials with glass transition temperatures (Tg) in the range of 130−190°C and melting temperatures (Tm) in the range of 220−350°C. In a second series of PEAs, phenylhydroquinone, bisphenol‐A and 3,3′‐dimethylbisphenol‐A were used as diphenols. All but one PEA of the second series are amorphous materials with good solubility in chloroform and other organic solvents. GPC measurements indicated viscosity‐average molecular weights (M̄v) up to 38 000.
Synthesis and free radical polymerization of p‐methylseleno‐ and p‐phenylselenostyrenes
Authors: Ando Tsugumichi , Kwon Tae Seok , Kitagawa Akiko , Tanemura Takahiro , Kondo Shuji , Kunisada Hideo , Yuki Yasuo
Published: April 2003

p‐Methylselenostyrene (1) and p‐phenylselenostyrene (2) as selenium‐containing vinyl monomers were prepared. Both monomers are readily polymerized free radically to afford the corresponding polymers having molecular weight of about 20 000 ∼ 150 000. These homopolymers are stable below 300°C. From the copolymerization with styrene, Q values of 1 and 2 were calculated to be 1,18 and 1,03, respectively. On the other hand, e values of these monomers are −0,24 and −0,04, respectively, indicating the electron withdrawing character of the seleno groups.
The effect of alkyl chain length of amphiphilic phospholipid polyurethanes on haemocompatibilities
Authors: Li Yu‐Jun , Bahulekar Raman , Chen Tian‐Ming , Wang Yan‐Feng , Kodama Makoto , Nakaya Tadao
Published: April 2003

A series of phospholipid diols based on different lengths of alkyl chains such as eicosyl, stearyl, cetyl, lauryl, octyl, and butyl was synthesized and characterized. The phospholipid diols were subjected a polyaddition polymerization with hexamethylene diisocyanate. The haemocompatibilities of the resulting phospholipid polyurethanes were evaluated by platelet rich plasma contacting experiments and viewed by scanning electron microscopy. The polymers with alkyl chains of 20, 18, 16, and 12 carbon atoms showed much better haemocompatibilities than those with alkyl chains of 8 and 4 carbon atoms.
Chirality induction in cyclopolymerization, 5. Template effect of chiral acyclic 1,2‐glycols on the cyclo‐copolymerizations of (S)‐1,2‐propanediyl and (2S,3S)‐2,3‐butanediyl bis(4‐vinylbenzoate)s with styrene
Authors: Kakuchi Toyoji , Haba Osamu , Uesaka Takahiro , Yamauchi Yukio , Obata Makoto , Morimoto Yasushi , Yokota Kazuaki
Published: April 2003

The copolymerizations of (S)‐1,2‐propanediyl and (2S,3S)‐2,3‐butanediyl bis(4‐vinyl‐benzoate)s (2a and 2b) (M1) with styrene (M2) were carried out using 2,2′‐azoisobutyronitrile in toluene at 60 °C. For the cyclocopolymer 3, the extent of cyclization of 3b is higher than that of 3a. The monomer reactivity ratios are r1 = 8.34 and r2 = 0.27 for 2a and r1 = 6.82 and r2 = 0.19 for 2b. The specific rotation ([α] in deg · dm−1 · g−1 · cm3 c = 1.0 g · dL−1; CHCl3) changes from +230 to +176 for 3a and from +319 to +150 for 3b. After removing the chiral templates, the resulting poly[(methyl 4‐vinylbenzoate)‐co‐styrene]s showed a specific rotation ([α] in deg · dm−1 · g−1 · cm3 c = 1.0 g · dL−1; CHCl3) of −2 for 4a and of −8 for 4b, indicating that the (2S,3S)‐2,3‐butanediyl template shows a higher ability to cause asymmetric induction by comparison with the (S)‐1,2‐propanediyl one. A split Cotton effect due to the positive chirality was observed in the CD spectrum of 2 and the reversed one for 4. According to the CD exciton chirality method, the clockwise‐twist of two 4‐vinylbenzoate for 2 transmitted its chirality to 4 in which two 4‐vinylbenzoyl groups are twisted counterclockwise, i. e., an (R,R)‐configuration of vicinal (methyl 4‐vinylbenzoate) units in the main chain.
Copolymerization of ethylene and styrene with monocyclopentadienyltitanium trichloride/methylalumoxane catalyst
Authors: Oliva Leone , Mazza Stefano , Longo Pasquale
Published: April 2003

A series of ethylene‐styrene copolymerizations was carried out in the presence of cyclopentadienyltitanium trichloride and methylalumoxane at 20°C and at different comonomer feed compositions. By sequential extraction a copolymeric material with a styrene units content up to 36 mol‐% can be separated from the homopolymeric products. Some considerations about the relative reactivity of the comonomers and the regioregularity of the styrene insertion are made on the basis of the 13C NMR spectra.
Novel sulfur‐containing ferrocene polymers
Authors: Nuyken Oskar , Pöhlmann Thomas , Herberhold Max
Published: April 2003

Ferrocene‐containing polymers were synthesized via addition reaction of 1,1′‐dimercaptoferrocene (1) and 1,1′‐bis(2‐mercaptoethyl)ferrocene (2) to various diolefinic monomers such as dimethacrylates, divinyl ethers, divinyl sulfones and others. The dithiol 1 was also used as a monomer in condensation reactions with bifunctional acid chlorides. The polymerization of propylene sulfide in the presence of 1 as a bifunctional initiator was found to lead to polymers with a single central ferrocene unit.
A new methodology for studying multiple‐site‐type catalysts for the copolymerization of olefins
Authors: Soares J. B. P. , Abbott R. F. , Willis J. N. , Liu X.
Published: April 2003

A novel methodology is presented for studying the nature of multiple‐site‐type catalysts used for the synthesis of olefin copolymers. Experimental results of copolymer composition (short‐chain branching) versus molecular weight are obtained by analyzing high‐temperature gel‐permeation chromatography fractions with Fourier‐transform infrared spectroscopy. The molecular weight distribution obtained by gel‐permeation chromatography is deconvoluted to determine the number of different site types on the catalyst. The average copolymer composition of chains made on each site type is then determined from copolymer composition versus molecular weight data. It is also shown how to extend this methodology to determine the comonomer reactivity ratios per site type.
Acylation of (partially) silylated poly(vinyl alcohol)s with acyl chlorides. Vinyl chloride/vinyl ester copolymers by polymer analogous reaction
Authors: Mormann Werner , Wagner Thomas
Published: April 2003

Acylation of (partially) silylated poly(vinyl alcohol) with acyl chlorides and anhydrides was investigated under different conditions. In the presence of an acid acceptor (triethylamine) at temperatures below 50°C selective acylation of hydroxy groups was observed in agreement with literature data. At elevated temperature (160°C) without the use of an acid acceptor hydroxy and trimethylsiloxy groups react in an unselective manner. In addition, significant amounts of chlorine were found in the resulting polymers under these conditions, though no double bonds were detected. A polymer analogous reaction without incorporated chlorine was achieved with benzoic anhydride as acylating agent. Random distribution of chlorine and benzoyloxy groups most likely is obtained.
Third‐order nonlinear optical properties of poly(1,4‐vinylenephenylene) and its derivatives
Authors: Shim Hong‐Ku , Lee Kwang Sup , Jin Jung‐Il
Published: April 2003

Poly(1,4‐phenylenevinylene) (PPV) and its derivatives are readily processable and thermally stable polyconjugated polymers. Since PPV contains phenylene units, its structure can be easily altered and modified in the electronic structure. Moreover, PPV and the derivatives are easily prepared via water‐soluble or organic‐soluble precursor polymers. Various PPVs substituted with electron‐donating or ‐withdrawing groups were synthesized and their third‐order optical nonlinearities were investigated by third‐harmonic generation method or degenerate four‐wave mixing technique. When phenylene rings carry two alkoxy electron‐donating groups, the substituted PPVs show third‐order nonlinear optical properties up to an χ(3) value of about 10−9 esu. In order to obtain polymeric materials having high optical quality, PPV and silica alkoxide can be mixed successfully by sol‐gel processing without any phase separation or precipitation. This unusual organic‐inorganic hybrid shows a great advantage in the photonics applications.
Characterization of the differences in the crystallinity from surface to bulk of compression‐molded polypropene sheets using attenuated total reflection fourier‐transform IR spectroscopy
Authors: Kawamoto Naoshi , Mori Hideharu , Nitta Koh‐hei , Yui Nobuhiko , Terano Minoru
Published: April 2003

The crystallinities of compression‐molded polypropene sheets were investigated by applying Fourier‐transform (FT)‐IR and attenuated total reflection (ATR) FT‐IR analyses. Two internal reflection elements, Ge and KRS‐5, with an angle of incidence of 45°, were used to obtain the depth profiles of the crystallinity of polypropene sheets from the surface to bulk. The crystallinity in the region from the surface to about 0,7 μm depth was considerably lower than that in bulk. Polypropene sheets with higher comonomer content showed the same tendency, which was enhanced with decreasing molding temperature.
Drawn gel films of blends of ultrahigh‐molecular‐weight polyethylenes and low‐molecular‐weight short‐chain branched polyethylene
Authors: Yeh Jen‐taut , Lin Yu‐lang , Fan‐Chiang Chien‐cheng
Published: April 2003

A critical concentration was found for different compositions of UHMWPE/SBPE solutions, at which the concentration dependence of the reduced viscosity changes from low to high power. The critical concentration (Cc) is shifted to a higher value with increasing amount of SBPE in the UHMWPE/SBPE gel. The birefringence of the drawn films suggests that the degree of orientation of UHMWPE molecules along the drawing direction increases with the draw ratio. The increased orientation of UHMWPE improves the tensile strength and moduli of the drawn films. The draw ratios of gel films prepared from each blend of UHMWPE and SBPE exhibits a maximum value when the samples were prepared at concentrations close to their critical concentration. On the other hand, the maximum draw ratio obtained for gel films prepared near their Cc decreases significantly at higher weight ratios of SBPE to UHMWPE. In contrast, the gel films with less than 2 wt.‐% of SBPE in UHMWPE yield a higher maximum draw ratio than the sample prepared from pure UHMWPE gel. Possible mechanisms accounting for this behavior are proposed.
Polymerization of methacrylic acid esters with the aged system of lanthanum versatate and p‐chlorobenzenediazonium tetrafluoroborate
Authors: Sato Tsuneyuki , Naruse Motokazu , Toyosu Kentaro , Seno Makiko
Published: April 2003

The aged system of lanthanum versatate (1) and p‐chlorobenzenediazonium tetrafluoroborate (2) was found to initiate effectively the radical polymerization of acrylic monomers including alkyl methacrylates, butyl acrylate and acrylonitrile, although its initiating activity is lower than that of the non‐aged system. The polymerization of methyl methacrylate (3) with the aged 1/2 system was studied kinetically in acetone. The initial polymerization rate (Rp) is expressed by Rp = Kċ[aged 1/2]0.80 ċ [3]1.1 at 50°C. The overall activation energy of the polymerization is 59.0 kJ ċ mol−1. The molecular weight of the resulting poly(3) formed in the early stage increases with increasing conversion. The polymerization system involves a persistent radical showing a four‐line EPR spectrum with a g‐value of 2.004. A three‐line spectrum due to the nitroxyl radical was also observed at lower monomer concentrations. The total concentration of persistent radicals was found to correspond well to the instantaneous polymerization rate. The copolymerization of styrene (M1) and 3 (M2) with the aged initiator system was examined at 50°C in acetone. r1 and r2 are 0.19 and 0.47, respectively. The former is considerably smaller than that (0.52) reported for the conventional radical polymerization.
Polyelectrolyte complexes obtained by radical polymerization in the presence of chitosan
Authors: Cerrai Piero , Guerra Giulio D. , Tricoli Mario , Maltinti Simona , Barbani Niccoletta , Petarca Luigi
Published: April 2003

The radical polymerization of acrylic acid and sodium 4‐styrenesulfonate in the presence of chitosan as a template gives insoluble products, identified as the polyelectrolyte complexes chitosan‐poly(acrylic acid) and chitosan‐poly(4‐styrenesulfonate). Kinetic results do not permit to propose any mechanism in the first case, while suggest a “pick‐up” one in the second. The polyelectrolyte complexes have been characterized by FT‐IR spectroscopy, X‐ray diffractometry, optical and scanning electron microscopies, differential scanning calorimetry and thermogravimetric analysis. The results obtained indicate an ordered structure for the first complex, while the second one appears similar to that obtained by reacting the parent polymers. Therefore, the template polymerization technique appears advantageous only for the synthesis of the chitosan‐poly(acrylic acid) complex. The thermal analysis shows that the complexes undergo two successive modifications on heating. FT‐IR analysis demonstrates that the first process is an esterification between the hydroxyls of chitosan and the acidic groups of both daughter polymers; the second one appears to be an amidation of the chitosan ammonium groups only with the sulfonate groups.
Polymerization of ethylene oxide using yttrium isopropoxide
Authors: Choi Young K. , Stevels Willem M. , Ankoné Marc J. K. , Dijkstra Pieter J. , Kim Sung W. , Feijen Jan
Published: April 2003

Well defined poly(ethylene oxide)s were prepared using yttrium isopropoxide as an initiator. End group analysis using 1H‐ and 13C NMR spectroscopy revealed that only polymers with isopropyl ether and hydroxyl end groups were produced. The molecular weight is controlled by the initial amount of initiator added and low polydispersity polymer (Mw/Mn ≈ 1.1) was isolated. Sequential polymerization indicated the suitability of this initiator for macromolecular engineering.
Polymer microspheres prepared with a macroinitiator, 2. Sugar balls from 2‐methacryloyloxyethyl‐D‐glucopyranoside
Authors: Kitano Hiromi , Kawabata Junko , Muramoto Tadashi
Published: April 2003

Macroinitiator was prepared by the coupling of the disuccinimidyl ester of 4,4′‐azobis(cyanovaleric acid) with poly(methacryloyloxyethyl‐D‐glucopyranoside) (PMEGlc) with an amino group at its end. Styrene and divinylbenzene were copolymerized using the initiator in the presence of sodium dodecylsulfate. The polymer microspheres obtained have PMEGlc chains on their surfaces (“sugar balls”). Aggregation phenomena were observed when a solution of lectin (Con‐A) was added to the suspension, due to a specific recognition of sugar residues on the microsphere by a tetrameric lectin molecule. A suspension of sugar balls could not be flocculated even upon addition of an aqueous 3M NaCl solution due to the thick diffuse layer composed of PMEGlc chains on their surfaces. The utility of macroinitiators to prepare various polymer materials which have biomedical functions on their surfaces is suggested.
A kinetic study of free‐radical copolymerization of butyl acrylate with methyl methacrylate in solution
Authors: Madruga Enrique López , Fernández‐García Marta
Published: April 2003

Free‐radical copolymerization at 50°C of butyl acrylate with methyl methacrylate was carried out in benzene solution using 3 and 5 mol/L as the overall concentration of monomers. Both the reactivity ratios and the rate coefficients of copolymerization are affected by the total monomer concentration. Reactivity ratios were analyzed on the basis of the “bootstrap” model, and the copolymerization rate is interpreted assuming a penultimate effect upon the propagation reaction.
Estimation of the conformational characteristics of polyurethane chains
Authors: Kašpárková Věra , Šimek Lubomír , Bohdanecký Miloslav
Published: April 2003

Linear polyurethanes (PUR‐Dk) were prepared by reacting 4,4′‐methylenediphenyl diisocyanate (MDI) with low‐molecular‐weight diols HO(CH2)kOH (k = 2, 3, 4, and 6) and fractionated by precipitation or extraction with mixtures of N,N‐dimethylformamide (DMF) and dibutyl ether (DBE). The fractions were characterized by their weight‐average molecular weights Mw (light scattering) and intrinsic viscosities [η] in DMF (good solvent) and mixtures of DMF with DBE (poor solvents). The Kuhn statistical segment length lK was evaluated from the intrinsic viscosities in poor solvents. Low values of lK, (12 to 14) × 10−8 cm, indicate that benzene rings and virtual double bonds (urethane groups) confine neighbour interactions to bonds within the repeating units and assure independent rotations at the bonds adjoining them.
Thermodynamics of polymer blends based on poly(methyl acrylate) and poly(vinyl acetate) with different molecular weights
Authors: Casarino Piera , Brunacci Antonio , Pedemonte Enrico
Published: April 2003

In this work a study on thermodynamics of polymer blends, based on poly(methyl acrylate) (PMA) and poly(vinyl acetate) (PVAc), was carried out. Our foremost aim was to examine the molecular weight effect on polymer compatibility. The results confirm our hypothesis: the interaction parameter χ12, varies abruptly in a very restricted molecular weight range. In this way, it can be concluded that molecular weight, as well as other parameters (i.e. lateral group hindrance, chain functionalization, composition temperature and so on), influences greatly polymer miscibility.
Synthesis and photoconductivity study of polystyrene‐fullerene
Authors: Wang Changchun , Pan Baorong , Fu Shoukuan , Jiang Kejian , Chen Hongzheng , Wang Mang
Published: April 2003

An anionic polymerization process was adopted to synthesize polymeric fullerene (C60) derivatives. Ultraviolet/visible spectroscopy, differential scanning calorimetry and gel‐permeation chromatography demonstrate that C60 is chemically bonded to polystyrene, and that it is mainly bis‐substituted. The polystyrene‐C60 derivatives are soluble in a variety of solvents, such as tetrahydrofuran, toluene, trichloromethane. The material exerts good photoconductivity.
Synthesis and ring‐opening polymerization of 2‐acetoxymethyl‐2‐alkyltrimethylene carbonates and of 2‐methoxycarbonyl‐2‐methyltrimethylene carbonate; a comparison with the polymerization of 2,2‐dimethyltrimethylene carbonate
Authors: Weilandt Karl D. , Keul Helmut , Höcker Hartwig
Published: April 2003

The polymerization of 2‐acetoxymethyl‐2‐alkyltrimethylene carbonates (alkyl = methyl: AMTC, alkyl = ethyl: AETC) and of 2‐methoxycarbonyl‐2‐methyltrimethylene carbonate (MMTC) in toluene with sec‐butyllithium as initiator results in the respective polymer with yields between 78% and 88%. The analysis of the polymer microstructure by means of NMR spectroscopy reveals linear chains without branching due to an attack of the active chain end at the ester moiety of the repeating units. Poly(MMTC) and poly(‐AETC) afford crystalline materials upon precipitation from solution while poly‐(AMTC) is amorphous; after quenching from the melt all materials are amorphous. Copolymerization of AMTC, AETC and MMTC with 2,2‐dimethyltrimethylene carbonate (DTC) results in random copolymers. The kinetics of the polymerization of AETC and MMTC revealed that the ester side chain enhances the rate of propagation compared to the polymerization of DTC. The apparent rate constants of propagation in toluene with lithium alcoholate as active sites at 23°C were determined to be kappDTC = 4 ċ 10−3 s−1, kappAETC = 4,28 ċ 10−2 s−1, and kappMMTC = 2,57 ċ 10−2 s−1. Studies of ring‐chain equilibria in solution of tetrahydrofuran revealed that on the basis of the theory of Jacobson‐Stockmayer the characteristic ratios of the polymers are C∞PDTC = 7,1, C∞PMMTC = 8,6, C∞PAETC = 9,9, and C∞PAMTC = 13,4.
Synthesis of poly(enaminonitriles) containing arylate and aramide units, and their thermal properties
Authors: Bae Jang‐Soon , Gong Myoung‐Seon
Published: April 2003

Various aromatic diamines with preformed arylate and aramide linkages were obtained by the reaction of p‐nitrobenzoyl chloride with aromatic diols and diamines, and terephthaloyl chloride with p‐nitrophenol and p‐nitroaniline, followed by hydrogenation. New poly(enaminonitriles) containing arylate or aramide units in the main chain were prepared by reacting p‐bis(1‐chloro‐2,2‐dicyanovinyl)benzene (2) with the corresponding ester‐ or amide‐containing aromatic diamines. These polymers possess intrinsic viscosities of 0.38–0.53 dL/g. They are easily soluble in polar aprotic solvents such as dimethyl sulfoxide, N,N‐dimethylformamide and N‐methyl‐2‐pyrrolidone. Hard and brittle films were easily cast from DMF solutions. These polymers show a broad exothermic peak in differential scanning calorimetry and undergo a curing reaction around 350°C to form insoluble materials. Almost all the poly(enaminonitriles) exhibited no appreciable decomposition below 400°C, 10% weight loss being recorded above 450°C, and a good thermal stability of 83–92% residual weight at 500°C.