bluuebunny/crossref_metadata_2025 huggingface dataset:
SEM study on fracture behavior of ethylene/propylene block copolymers and their blends
Authors: Sun Zhenhua , Yu Fusheng
Published: April 2003

The toughening effect of the separate phases of ethylene/propylene block copolymers and their blends was studied by scanning electron microscopy (SEM). The results obtained show that the interfacial adhesion between separate phases and the isotactic polypropene (iPP) matrix in ethylene/propylene block copolymers is strong at room temperature, but poor at low temperature; specimens exhibit tearing of separate phases during fracture at room temperature, but interfacial fracture between separate phases and the iPP matrix at low temperature. From the characteristics of fractographs of ethylene/propylene block copolymers and their blends, it could be concluded that the separate phases improve the toughness of specimens in several ways: they promote the plastic deformation of the iPP, and they can be deformed and fractured themselves during the fracture process. However, it was shown that the plastic deformation processes, such as multiple‐crazing, shear yielding, etc. of the matrix are the dominant mechanisms of energy absorption in highly toughened ethylene/propylene block copolymers and their blends. The deformation and fracture of separate phases are only of secondary importance.
Polymeric chiral crown ethers, 7. Synthesis of polymers incorporating methyl glycosides of α‐D‐altrose, α‐D‐galactose, α‐D‐glucose and α‐D‐mannose residues via copolymerization of divinyl ethers
Authors: Kakuchi Toyoji , Haba Osamu , Yokota Kazuaki
Published: April 2003

Polymers with chiral asymmetric crown ether units (5, 6, 7 and 8) were synthesized via cationic cyclopolymerization of methyl 2,3‐bis{O‐[2‐(2‐vinyloxyethoxy)ethyl]}‐4,6‐O‐benzylidene α‐D‐altro‐, α‐D‐galacto‐, α‐D‐gluco‐ and α‐D‐manhopyranosides (1, 2, 3 and 4), respectively. The enantioselective transport of the methyl ester of phenylglycine (PhGlyOCH3) and phenylalanine (PhAlaOCH3) was examined through a bulk chloroform solution of chiral polymers from one aqueous solution to another. The transport rate of PhAlaOCH3 was larger than that of PhGlyOCH3 for every host polymer. For polymer 7, the optical purity of PhAlaOCH3 transported from one to the other phase was 12,6%, and the ratio of rate constants for the faster moving enantiomer A and the slower moving enantiomer B (kA*/kB*) was 1,48. The faster moving enantiomer was the L‐isomer except for the systems polymer 7 − PhAlaOCH3 and polymer 8 − PhAlaOCH3. This enantioselectivity is caused by the diastereotopic faces of the crown ether units in the host polymers.
Novel degradable methacrylate‐ and p‐vinylphenoxy‐based oligomers, 2. Photopolymerization and acid‐catalysed degradation
Authors: Ericsson Jan , Hult Anders
Published: April 2003

Five novel photocrosslinkable oligomers were evaluated with regard to polymerization and acid‐catalysed degradation. The oligomers include either a methacrylate or p‐vinylphenoxy unit as the polymerizable moiety. A carbonate functionality susceptible to acid‐catalysed degradation is also incorporated. This work shows that it is possible to formulate an oligomer‐based photo‐curable coating which can be polymerized to an insoluble matrix. In the case of the styrene‐type dicarbonates, no pure coatings can be studied at room temperature, and at elevated temperatures cationic polymerization competes with degradation. They can, however, be degraded to soluble products at reasonable temperatures if the system is exposed to a strong acid catalyst.
Characterisation of macroporous polystyrene and its relationship to the adsorption of Cephalosporin C
Authors: Huxham Ian Maximillian , Rowatt Brian
Published: April 2003

Low‐temperature specimen preparation techniques, energy‐filtering electron microscopy, quantitative image analysis and elemental mapping are applied to an analysis of two macroporous, hydrated, polystyrene sorbents (XAD4® and PS50X2T) in order to determine whether or not minor differences in the apparent binding behaviour of Cephalosporin C to each hydrated sorbent can be related to specific determinants of polymer porosity. Mercury intrusion volume calculations suggest that each polymer has almost identical characteristics in the dry state. In contrast, electron microscopically‐derived pore profile measurements from the hydrated polymer suggest that XAD4® has a greater proportion of pore area associated with small (5–50 nm) diameter pores and a correspondingly smaller proportion of its pore area associated with the larger (80–150 nm) pore diameters as compared to PS50X2T, and that these differences are associated with changes in the local distribution of adsorbed Cephalosporin C within the polymer's porous domains.
Polymerization reaction with diphenylphosphoryl azide. Preparation of polyamides, polyureas and polyurethanes
Authors: Nishi Norio , Tsunemi Masahiko , Nakamura Kunio , Tokura Seiichi
Published: April 2003

The preparation of various polyamides, polyureas and polyurethanes by polymerization reactions with diphenylphosphoryl azide (DPPA) was investigated. Various polyamides were obtained very conveniently by polymerization of aminocarboxylic acids or copolymerization of dicarboxylic acids and diamines. Polyureas were mainly obtained by conversion of dicarboxylic acids to acyl azides with DPPA and then to isocyanates, followed by copolymerization of these diisocyanates with diamines. Further, the polymerization of some aminocarboxylic acids that have an amino group of low nucleophilicity (such as p‐aminobenzoic acid) was found to give polyureas instead of polyamides by direct polymerization. Polyurethanes were also obtained from dicarboxylic acids and diols through the Curtius rearrangement of acyl azides, similarly as in the polyurea preparations. The products were identified with the help of IR spectra and elemental analyses, and their molecular weights were evaluated viscometrically.
Polymères photoréticulables à unités cinnamiques, 3. Photoréticulation
Authors: Remmas Miloud , Soutif Jean‐Claude , Brosse Jean‐Claude
Published: April 2003

Photocrosslinking of polymers, prepared from cinnamic acid derivatives, by chemical modification of poly(vinyl alcohol) or polycondensation of difunctional cinnamic acid derivatives has been studied. With Michler's ketone (sytem. name: 4,4′‐bis(dimethylamino)benzophenone), crosslinking of copolymers is improved. 2‐Nitrofluorene or 9‐xanthenone have little effect on the crosslinking rate. Photocrosslinking of poly(α‐cyano‐4‐vinylcinnamic acid), poly(ethyl α‐cyano‐4‐vinylcinnamate) and their copolymers is enhanced in the presence of 2‐hydroxy‐2‐methylpropiophenone, but the effect is lowered in the case of its acrylic esters or their (co)polymers.
Emulsion polymerization of butadiene, 4. Effect of thiols
Authors: Weerts Pierre A. , van der Loos Jos L. M. , German Anton L.
Published: April 2003

The role of thiols of low water solubility, commonly used in the emulsion polymerization of butadiene, has been considered. The following effects have become apparent: (1) dodecanethiols act as efficient chain transfer agents in limiting the formation of heavily cross‐linked polymer networks; (2) the monomer concentration within the particles is not influenced by such thiols; (3) C12‐thiol radicals do not desorb because of their extremely low water solubility. The ‘promoting effect’ of thiols in emulsion polymerizations of diene‐hydrocarbons is still poorly understood, but it appears to be related to impurities present in the emulsifier, as it was found completely absent in emulsifier‐free polymerizations.
4‐(α,α‐dimethylbenzyl)phenyl methacrylate, 2. Polymerization in N,N‐dimethylformamide
Authors: van Ekenstein Gert O. R. Alberda , Tan Y. Yong
Published: April 2003

The polymerization rate of 4‐(α,α‐dimethylbenzyl)phenyl methacrylate in DMF at 70°C is of the order 1,6 in [monomer] and first order in [AIBN], which deviates from classical kinetics. This could be reconciled by a reaction scheme in which dimeric monomer associates and a spontaneous termination are postulated. The scheme is supported by the dependence of the kinetic chain length, v, on the 1,6‐th power in [monomer] and zeroth power in [AIBN]. The degree of polymerization is smaller than v, which indicates some chain transfer. A remarkable feature is the constancy of the dispersion degree, M̄w/M̄n, of the polymers of about 1,4 up to high degrees of conversion. The overall activation energy of the polymerization, Ea, is 60,1 kJ · mol−1, and the preexponential factor ln A ≈ 15,5 (A in (mol · dm−3)−1,5 · s−1). The polymer chains seem to have a rod‐like character in THF as deduced from the Mark‐Houwink exponent of 1,46. In toluene the polymer tends to form associates.
Regular folding in solution‐grown polyethylene crystal, 2. Supportive evidences
Authors: Chang Hwei‐Liang , Hu Andrew Teh
Published: April 2003

It is shown here that the coordinated pair chain folding (CPCF) model can explain the evidences reported about polymer chain conformation in solution‐grown polyethylene (PE) single crystals from neutron scattering and infrared (IR) studies. Thus the CPCF model can revive the consideration that a polymer chain should fold regularly rather than randomly in solution‐grown PE single crystals. The start‐to‐crystallization position of a polymer chain, dominantly from the inner part (other than chain ends) of the polymer chain itself, explains the “superfolding” effect. The scattering function calculated from those stems allocated in the form of a CPCF model with superfolding coincides with the reported data from small angle and intermediate angle neutron scattering experiments. Interchain interference destroys the neutron peak at Q = 0,7 Å−1, thus settling the “no peak” argument for equivalent Bragg spacing 8,9 Å. The CPCF model satisfies the reported statement from IR studies: “The correlation splitting of the CD2 bending vibration is not generally observed.” The splitting observed in other experiments coincides with the stem arrangement of the CPCF model with partial intrachain coalescence, which is caused by a faster crystallization rate, the energy state being a little higher than that without local coalescence.
Soluble polystyrene‐block‐poly(p‐phenylene) block copolymers prepared from polystyrene‐block‐poly(1,3‐cyclohexadiene) precursors. Study of the aromatization process
Authors: Zhong Xing Fu , François Bernard
Published: April 2003

Polystyrene‐block‐poly(p‐phenylene) block copolymers were prepared from polystyrene‐block‐poly(1,3‐cyclohexadiene) (PS‐PCHD) precursors. The PS‐PCHD copolymers were initiated by sec‐butyllithium in benzene. The aromatization of poly(1,3‐cyclohexadiene) sequences was carried out by dehydrogenation with substituted quinones. Secondary reactions occur during this reaction leading to defects in the poly(p‐phenylene) (PPP) sequences which limit the mean length of conjugated blocks at about 11–12 phenylene units. The defects result from the addition of hydroquinone ether groups to the chain. The influence of experimental conditions (nature of quinone, additives, temperature) on the aromatization yield and defect content is studied. The reaction with p‐chloranil

System. name: tetrachloro‐p‐benzoquinone.

at 130°C gives the best results. The formation of aggregates during this reaction is observed and explains the final slow kinetics. The purified copolymers are partly aggregated into micelles with a PPP core. For a given polystyrene sequence the fraction of aggregated chains and the size of PPP core increases with the length of PPP sequences. Improvements of PPP blocks are expected by a better control of the aggregation process.
Concentration of aqueous alcoholic solutions through a modified silicone rubber membrane by pervaporation and evapomeation
Authors: Uragami Tadashi , Shinomiya Hidenori
Published: April 2003

Permeation and separation characteristics for aqueous alcoholic solutions through a modified silicone rubber membrane containing poly(propylene glycol) in the polymer chain were studied by both pervaporation and evapomeation. Both the permeation rates in pervaporation and evapomeation increase, and the selectivity for ethanol in pervaporation does not change but that in evapomeation increases with an increase in the permeation temperature. When the temperature in the membrane surroundings was kept constant and the temperature of the aqueous ethanol solution was varied, or vice versa, it was found that the permeation rate and the permselectivity for ethanol are significantly influenced by the temperature in each permeation condition. The selectivity for alcohols through the modified silicone rubber membrane in the evapomeation method with control of the temperature difference decreases in the order methanol > ethanol > 1‐propanol.
Dimensions of poly(methyl methacrylate) molecules in poor solvents
Authors: Guaita Marino , Chiantore Oscar , Burchard Walther
Published: April 2003

Dilute solutions of narrow distribution poly(methyl methacrylate) (PMMA) samples in the poor solvents, 2‐ethoxyethanol and acetonitrile, are studied by dynamic and static light scattering and viscometry. Theta temperatures at 37,8°C and 32,3°C, respectively, are found, where the constants KΘ of the Mark‐Houwink‐Sakurada relation are 5,6 · 10−2 cm3/g and 4,0 · 10−2 cm3/g. This implies that the unperturbed dimensions of PMMA molecules in 2‐ethoxyethanol are greater by 12% than in acetonitrile. The hydrodynamic radii in the two solvents and the radii of gyration in acetonitrile are found to decrease smoothly with decreasing temperature passing the theta temperatures. Data treatment according to the thermal blob model shows that the macromolecular coils, still close to Gaussian statistics, move toward the excluded volume regime above the theta temperature Θ and toward the collapse regime below Θ.
Conformational volume in statistics of chain molecules
Authors: Bleha Tomás̆
Published: April 2003

The conformational volume Vc represents a contribution to the partial molar volume V̄ of solutes which arises due to the non‐identical volume of conformers in chain molecules. The paper presents expressions for calculations of the term Vc based on the matrix method of conformational statistics. Starting from literature data on the volume differences in conformational diads, the conformational volume of poly(methylene) was calculated as a function of temperature and pressure. The combination of the results calculated with experimental data for nonane shows that the conformational term amounts to about 2% of the value of V̄ and several percent in the temperature coefficient of V̄. The theory of the conformational volume is presented as a generalization of existing empirical additive schemes for the calculation of the partial molar volume of linear‐chain solutes.
Sequence analysis and comonomer interactions in poly[(4‐chlorophenyl methacrylate)‐co‐(methyl methacrylate)]s
Authors: Hiller Wolf‐Gerald , Pasch Harald , Lampe Irene V.
Published: April 2003

Copolymers of 4‐chlorophenyl methacrylate and methyl methacrylate were prepared and investigated by 1H and 13C NMR spectroscopy. The copolymer composition, determined by chlorine analysis, 1H and 13C NMR, was found to be close to the initial composition of the monomer mixture. The sequence analysis was carried out by analyzing the methoxy signals of the 1H NMR spectra. Six out of ten tactic and compositional triads could be resolved. It was found that the copolymers are predominantly syndiotactic and the compositional and tactic triad populations are given. The aromatic carbon atoms are sensitive towards compositional and tactic sequence effects, which results in a switch of the order of the tactic signals at different aromatic carbon atoms.
Application of projection matrices to the calculation of unperturbed dimensions of chain polymers
Authors: Hoshino Yoshiaki , Miyake Akira
Published: April 2003

The projection operator method of matrix algebra is applied to calculate the unperturbed dimensions of an independently hindered rotating bond model for linear chain molecules. It does not require eigenvectors of a given transformation matrix in order to evaluate products of that matrix. This is an advantage to usual matrix diagonalization methods. As a result, we obtained four different types of conformations depending upon the values of parameters adopted. One of them shows a typical dependence on the number of bonds N, which has also been given by the usual matrix diagonalization method. Two further conformations are rather extended compared with the first one. In addition, as the fourth one we obtained also a helix‐like conformation. These conformation types correspond to those previously obtained by continuous models for stiff‐chain polymers.
Blend phase diagrams recorded with cast films
Authors: Yu Dan , Andradi Laksiri N. , Hellmann Goetz P.
Published: April 2003

Phase diagrams of amorphous polymer blends are discussed that are recorded using cast films. Films of all blend compositions were cast at temperatures ranging over a wide interval, using different solvents, both above and below the glass transition temperatures of the blends. Phase diagrams thereby obtained can, if there is a proper choice of solvents and conditions, show the miscibility of polymers not only in the liquid but also in the glassy state. The theory of blend film casting is analyzed using the classical Flory‐Huggins model for compatibility and the Fox‐equation for the glass transition. It turns out that miscibility is reliably determined when slightly selective solvents are used. Errors made with non‐selective and too selective solvents are estimated. The film‐casting method was tested with blends of poly(methyl methacrylate) and random copolymers of styrene and methyl methacrylate.
4‐(α,α‐dimethylbenzyl)phenyl methacrylate, 3. Synthesis, tacticity and glass transition temperatures of its polymers
Authors: van Ekenstein Gert O. R. Alberda , Tan Y. Yong
Published: April 2003

Depending on the kind of initiator, anionic polymerization of 4‐(α,α‐dimethylbenzyl)phenyl methacrylate in toluene at −78°C led either to highly isotactic or predominantly syndiotactic polymers as determined by 13C NMR spectroscopy. The glass transition temperature difference between the syndiotactic and isotactic polymer appeared to be smaller than in case of poly(alkyl methacrylates), probably because of a larger stiffening effect by the bulky aromatic ester group on the isotactic backbone than on the syndiotactic one.
Synthesis of polymers containing pseudohalide groups by cationic polymerization, 3. Preliminary study of the polymerization and copolymerization of alkenyl monomers containing azide groups
Authors: Cheradame Hervé , Habimana Jean de la Croix , Rousset Eliane , Chen Frank
Published: April 2003

The cationic polymerization or copolymerization of various alkenyl monomers was investigated in the presence of azide groups. The monomers were either of the n‐π‐donor type, such as vinyl ethers, or π‐donors, such as isobutene (2‐methylpropene) or styrene. The azide groups were introduced by a suitable comonomer, such as 2‐azidoethyl vinyl ether (AEVE) or 4‐azidomethyl‐styrene (AMS). The initiator was TiCl4. 3‐Azido‐2‐methyl‐1‐propene (AMP) (methallyl azide) revealed to be not polymerizable. In the case of vinyl ethers, their cationic polymerization in the presence of azide groups requires high Lewis acid concentrations, according to the work previously carried out on oxetanes. In the case of the less nucleophilic monomers styrene and isobutene it was shown that cationic polymerization takes place provided that the initiator concentration is equal or higher than that of the azide group. This effect was assigned to a complexation between the Lewis acid and the azide group, and consequently the more nucleophilic the monomers (heterocyclics or vinyl ethers) are the lower the required Lewis acid concentration to observe cationic polymerization. Some evidence was found showing that the isobutene polymerization carried out in the presence of a molecular containing an azide group results in an azido‐endcapped polyisobutene while in the case of styrene and vinyl ethers cationic copolymerization with comonomers containing azide groups was observed.
The glass transition of blends of poly(2,6‐dimethylphenylene oxide) and polystyrene‐block‐poly(2,2‐dimethyltrimethylene carbonate)
Authors: Kummerlöwe Claudia , Kammer Hans‐Werner , Morgenstern Ute , Berger Werner , Keul Helmut , Höcker Hartwig
Published: April 2003

The miscibility of poly(2,6‐dimethylphenylene oxide) (PPO) with polystyrene‐block‐poly(2,2‐dimethyltrimethylene carbonate) (PS‐block‐PDTC) was studied and compared with the corresponding PPO/PS blends. PPO/PS‐block‐PDTC blends show two thermal transitions in the temperature range investigated; that is the melting of the DTC block and the glass transition of the mixed PPO/PS block phase. The Tg values obtained are discussed by means of the Fox and Gordon‐Taylor equation. The influence of the PDTC block leads to higher Tg values of the PPO/PS block mixture than of the corresponding homopolymer blend.
Copolymerization of 5‐norbornen‐2‐yl acetate with cycloalkenes by the metathesis catalyst WCl6/(CH3)4Sn
Authors: Balcar Hynek , Dosedlová Alena
Published: April 2003

Ring‐opening metathesis copolymerization of 5‐norbornen‐2‐yl

System. name: bicyclo[2.2.1]hept‐5‐en‐2‐yl.

acetate (NBEAc; 80% endo) with cyclooctene (COE) and norbornene

System. name: bicyclo[2.2.1]hept‐2‐ene.

(NBE) was studied using WCl6/(CH3)4Sn as catalytic system. The copolymerization parameters (r1 = r2 = 1 for the NBEAc/NBE system and r1 = 1/r2 = 132 for the NBEAc/COE system) show that the reactivity of the monomers is not affected by the presence of an ester substituent but that it depends on the structure of the hydrocarbon cycle. Thus the well known inhibition effect of the ester group may be concluded not to lie in the propagation step of the catalytic cycle.
Doped polymers by oxidative polymerization, 2. Synthesis and electrical conductivity of oxidized poly[trans‐1,2‐di(2‐furyl)ethylene]
Authors: Koßmehl Gerhard , Greczmiel Thomas
Published: April 2003

trans‐1,2‐Di(2‐furyl)ethylene (2) was oxidized with several inorganic oxidants such as FeCl3, CuCl2 and Na2S2O8 under varying conditions to give a “doped” polymer in a one‐step reaction. Such polymeric salts show typical semiconductor properties, and the electrical conductivity increases with increasing degree of oxidized units in the polymeric structure. The influence of the oxidizing agent and the conditions of the reaction on the composition and the electrical conductivity were studied. The black polymer, which was synthesized by oxidation with FeCl3 in a mole ratio monomer/oxidizing agent of 1 to 6 in acetonitrile for 16 h at 20°C, shows the highest electrical conductivity of 2,0 · 10−5 Ω−1 · cm−1.
An example of the thermal decomposition of a crystalline polymer — poly(l,6‐bis(N‐carbazolyl)‐2,4‐hexadiyne)
Authors: Bradner Friedrich P. , Shapiro Jacob S.
Published: April 2003

The thermal decomposition of poly(1,6‐bis(N‐carbazolyl)‐2,4‐hexadiyne) crystals, prepared by gamma radiation, was examined over a range of experimental conditions, the most important of which are temperature and crystal size. The only two significant products found were carbazole and to a lesser extent 9‐methylcarbazole. Decomposition kinetics, which applied to the two observed autoacceleratory regions, was best fitted to an Avrami‐Erofeyev equation with an exponent of two. The activation energy determined for the first autoacceleratory region was found to be higher than that determined for the second autoacceleratory region. A reaction mechanism is described based on stressinduced initiation, followed by either a molecular or a free‐radical non‐chain process. In an attempt to release stress, the polymer was observed to undergo sidegroup cleavage due to shearing of neighbouring polymer chains.
Analysis of the linear methods of determining copolymerization reactivity ratios, 12. Copolymerization of styrene or methyl methacrylate with N‐p‐tolylcitraconimide or fumarodinitrile
Authors: Braun Dietrich , Czerwinski Wojciech K. , Bednarski Ralf , Tüdős Ferenc , Kelen Tibor
Published: April 2003

For copolymerization of styrene or methyl methacrylate with N‐p‐tolylcitraconimide (in toluene) or fumarodinitrile (in benzene) at 60°C with 2,2′‐azoisobutyronitrile (AIBN) as initiator, the composition of the resulting copolymers was measured as a function of the monomer feed composition. To provide good accuracy of reaction modelling in terms of the terminal and penultimate models, the linearized forms of both models were applied assuring high sensitivity of the evaluation. Among the systems considered the styrene/fumarodinitrile system with r′1/r′1 ≈ 10 was found to copolymerize according to the penultimate mechanism to a significant degree.
Monomer‐isomerization polymerization, 35. Kinetics of monomer‐isomerization polymerization of 2‐butene with Ziegler‐Natta catalyst
Authors: Endo Kiyoshi , Ueda Ryuichi , Otsu Takayuki
Published: April 2003

The kinetics of monomer‐isomerization polymerizations of cis‐2‐butene with TiCl3/Al(C2H5)3 catalysts in the presence and absence of NiCl, was studied. Both the rate of isomerization and polymerization increased as a function of the concentrations of the monomer and catalyst. The apparent activation energies for the polymerization with TiCl3/Al(C2H5)3 and with TiCl3/NiCl2/Al(C2H5)3 were estimated to be 25,6 and 17,2 kJ/mol, respectively. This difference in the apparent activation energy for monomer‐isomerization polymerization may be accounted for by the rates of isomerization to 1‐butene. The reaction constants for the isomerization and polymerization were evaluated by simulation. The rate of polymerization with the TiCI3/Al(C2H5)3 catalyst was found to be about 40 times higher than that of isomerization, and in the presence of NiCl2, both rates become similar. From product analysis produced with TiCl3 and alkylaluminium compounds, it is concluded that the active sites for isomerization involve Ti2+ complexes and those for the polymerization involve Ti3+ complexes.
Structural and thermal investigations on aromatic polyoxadiazole/polyamide 6 blends
Authors: Calandrelli Luigi , Immirzi Barbara , Malinconico Mario , Martuscelli Ezio , Riva Fernando
Published: April 2003

Blends of poly(1,3,4‐oxadiazole‐2,5‐diyl‐1,4‐phenylene) (PODZ) and polyamide 6 (PA6) were obtained by a coagulation process from sulfuric acid solution. The resulting blends were studied by means of X‐ray diffraction and calorimetry using a DSC and a thermogravimetric apparatus. The PA6 crystallinity was found to be strongly influenced by the presence of PODZ and is dependent on the blend compositions. Below 30 wt.‐% of PA6 crystallinity disappeared completely. A preliminary investigation of morphology and mechanical properties was also carried out.
Synthesis of degradable terpolymers responding to external stimuli such as pH, ionic strength and temperature
Authors: Imasaka Kazumichi , Nagai Tsuneji , Yoshida Masaru , Fukuzaki Hironobu , Asano Masaharu , Kumakura Minoru
Published: April 2003

Degradable copolymers which respond to external stimuli such as pH, ionic strength, and temperature were successfully prepared by direct polycondensation of L‐lactic acid (LA), D,L‐mandelic acid (MA), and 3‐(p‐hydroxyphenyl)propionic acid (HPPA) without the use of a catalyst at 200°C by bubbling nitrogen through the solution. The molecular weights of the copolymers obtained were relatively low because of the low polymerizability of MA and HPPA, e. g., number‐average molecular weight M̄n ≦ 2100 and weight‐average molecular weight M̄w ≦ 4100. Poly{(L‐lactic acid)‐co‐(D,L‐mandelic acid)‐co‐[3‐(p‐hydroxyphenyl)propionic acid]} (poly(LA/MA/HPPA)) with a composition of the monomeric units (in mol‐%) LA:MA:HPPA = 80:10:10 showed rapid degradation after a lag time of 5 h within 48 h from the start of the test, in M/15 phosphate buffer solution (pH 7,2) at 37°C. With increasing pH and temperature, the rate of degradation was markedly accelerated.
A simplified wittig synthesis using polyacrylates with a terminal triphenylphosphonium group and polymerization of the macromonomers
Authors: Shen Wei‐ping , Jin Hong‐mei
Published: April 2003

In the presence of zinc halide, triphenylphosphine and chlorotrimethylsilane can be used directly to initiate group transfer polymerization of acrylate monomers. The resulting polymers with terminal triphenylphosphonium groups can be converted to the corresponding vinyl‐macromonomers by means of the Wittig reaction. We found that the vinyl‐macromonomers can be smoothly prepared with very good yields from the macromolecular phosphonium salts and aqueous formaldehyde in tetrahydrofuran/potassium hydroxide applying the phase transfer catalysed Wittig synthesis. The macromonomers were polymerized and copolymerized with styrene in butanone.
Copolymerization of N‐chlorophenylmaleimides with vinyl acetate
Authors: Konsulov Vitan B. , Grozeva Zoya S. , Kelen Tibor , Borbély János
Published: April 2003

By radical copolymerization, thermostable copolymers of N‐(2‐chlorophenyl)maleimide (2CPMI), N‐(3‐chlorophenyl)maleimide (3CPMI) and N‐(4‐chlorophenyl)maleimide (4CPMI) with vinyl acetate were prepared. The values of reactivity ratios determined according to the Kelen‐Tüdős method are: r2CPMI = 0,148 and rVA = 0,049; r3CPMI = 0,221 and rVA = 0,032; r4CPMI = 0,655 and rVA = 0,0. The position of the Cl atom in the phenyl ring of CPMI influences the copolymerization kinetics. 2CPMI exhibits the strongest tendency for cross propagation, 4CPMI has the highest ability for homopolymerization. Vinyl acetate in all the three systems forms inactive radicals. The thermostability of all three copolymers is higher than that of the vinyl acetate homopolymer and decreases in the order poly(3CPMI‐co‐VA) > poly(4‐CPMI‐co‐VA) > poly(2CPMI‐co‐VA).
Modifizierung von homo‐ und copolymeren des epichlorhydrins durch polymeranaloge umsetzungen
Authors: Nuyken Oskar , Lattermann Günter , Dannhorn Wolfgang , Vogel Rainer
Published: April 2003

Poly(epichlorohydrin) and poly(epichlorohydrin‐co‐ethylene oxide) were modified by reaction with potassium thiocyanate (KSCN), tetrabutylammonium p‐toluenesulfinate (NBu4SO2C7H7) and tetrabutylammonium benzenesulfinate (NBu4SO2C6H5). Though the substitution of chlorine in the polymers with these nucleophilic reagents in most cases is accompanied by side reactions, appropriate reaction conditions allow degrees of substitution higher than 90% to be obtained. The glass transition temperature (Tg) of the thiocyanate‐modified homo‐ and copolymer exhibits only a small increase with increasing degree of substitution. While the Tg of the original homo‐ and copolymer is observed at −20°C and −38°C, respectively, the glass transition of the highly substituted homopolymer occurs at −12°C and for the copolymer at −31°C. On the other hand, the thiocyanate‐modified polymers show a remarkably higher decomposition temperature of about 250°C as compared with that of the unmodified polymers (160–180°C). In addition, the solubility is markedly influenced by the substitution. While the original homo‐ and copolymers are soluble in, e.g., benzene and toluene, the highly modified products are only soluble in polar solvents such as THF, acetone, DMSO and diglyme. Introducing sulfonyl groups, the resulting polymers exhibit a glass transition temperature increased to a greater extent. For the homopolymer with the highest degree of substitution (98,3%), a Tg of 73°C is observed. Concerning the decomposition temperature, a drastical increase up to 370°C occurs. Finally the influence of phase transfer catalysts on the described reactions was investigated.
New macromonomeric initiators (macroinimers), 2 Gelation in bulk polymerization of styrene with macroinimers
Authors: Hazer Baki
Published: April 2003

Macroinimers were obtained by the reaction of 4,4′‐dicyano‐4,4′‐azovaleryl chloride (1), poly(ethylene glycol) and methacryloyl chloride. They were thermally homopolymerized and copolymerized with styrene in bulk (40 wt.‐%). Crosslinking increases as polymerization time increases.
Cationic polymerization of 1,2‐epoxy‐3‐nitropropane in the presence of ethylene glycol, 2 Higher oligodiols: Discrepancies with the activated monomer mechanism
Authors: Lagarde Florence , Reibel Leonard , Franta Emile
Published: April 2003

The cationic polymerization of 1,2‐epoxy‐3‐nitropropane (ENP) in the presence of ethylene glycol and boron trifluoride etherate is studied. The reaction was performed by adding the monomer stepwise in the reaction medium, so that the instantaneous mole ratio [ENP]/[OH] was below one, in order to favor the Activated Monomer Mechanism (AMM). We have shown previously that polymerization proceeds via AMM during the first two steps of the reaction (M̄n < 350). In this paper, we present our results concerning the subsequent stages. In addition to the expected molecules containing one ethylene glycol unit per chain $ [{\rm H \rlap{--} ( O}{\rm CHR}{\rm CH}_{\rm 2} \rlap{--} )_p {\rm OCH}_{\rm 2} {\rm - CH}_{\rm 2} {\rm O \rlap{--} ( CH}_{\rm 2}{\rm CHR}{\rm O\rlap{--} )}_q {\rm H (R} = {\rm CH}_{\rm 2} {\rm NO}_{\rm 2} )] $ we find also some α,ω‐ENP oligodiols which do not contain any ethylene glycol unit $ [{\rm H \rlap{--} ( O}{\rm CH}_{\rm 2}{\rm CHR}\rlap{--} )_i {\rm OH} $, some mono‐ or diethoxylated oligomers $ {\rm [C}_{\rm 2} {\rm H}_{\rm 5} \rlap{--} ({\rm O}{\rm CH}_{\rm 2}{\rm CHR\rlap{--} )}_i {\rm OH} $ and $ {\rm C}_{\rm 2} {\rm H}_{\rm 5} \rlap{--} ({\rm O}{\rm CH}_{\rm 2}{\rm CHR\rlap{--} )}_i {\rm OC}_{\rm 2} {\rm H}_{\rm 5} ] $ and some cyclics. The experimental hydroxyl concentration exceeds that introduced through the ethylene glycol used. Primary OH groups are present and the average molecular weight is limited to 500. The viscosity of the reaction medium decreases significantly when the polymerization is terminated, or simply when the medium is put in contact with atmospheric water.
On the activity of monomers and polymers on the basis of vinyl ethers of glycols in radical reactions
Authors: Nurkeeva Zauresh S. , Mun Grigorii A. , Golubev Vladimir B.
Published: April 2003

The absolute values of reaction constants of various radicals with vinyl ethers of glycols and aminoalcohols and with N‐vinyl‐2‐pyrrolidone have been determined by the spin‐trapping method. It was shown that the radicals are associated with the β‐carbon atoms of the vinyl groups. The kinetics of the process is considerably determined by the polarity of the monomers. It was established that the rate of elimination of H atoms from methylene groups in the side groups is considerably higher than that from methylene groups in the main chain of the macromolecules. The over‐all activity of poly(ethylene glycol monovinyl ether) is about 3 times higher than that of poly(diethylene glycola monovinyl ether).
Synthesis and reaction of polymethacrylate bearing cyclic carbonate moieties in the side chain
Authors: Kihara Nobuhiro , Endo Takeshi
Published: April 2003

(2‐Oxo‐1,3‐dioxolan‐4‐yl)methyl methacrylate (6) was prepared by fixation of CO2 into glycidyl

Systematic name: 2,3‐epoxypropyl.

methacrylate (2). Pure 6 polymerized spontaneously at room temperature. Radical polymerization of 6 (purity 94%) was carried out at 60°C using 2,2′‐azoisobutyronitrile as an initiator in dimethyl sulfoxide (DMSO) to give the corresponding homopolymer 1 (yield: 99%) which is soluble in DMSO and N,N‐dimethylformamide. 1 was reacted with butylamien at room temperature in DMSO for 24 h to the corresponding polymethacrylate 13 (yield: 100%) having a hydroxyurethane

The systematic name for urethanes is carbamates.

group in the side chain. No reaction of the ester groups of 1 with butylamine was observed. This was also demonstrated by the model reaction of (2‐oxo‐1,3‐dioxolan‐4‐yl)methyl isobutyrate (9) with butylamine in which the corresponding hydroxyurethanes 10, 11 and 12 were isolated in 96% yield.
Liquid‐crystalline polysiloxanes containing fluorene mesogens, 2. A new class of liquid‐crystalline side‐chain polymers with terminal 2‐fluorenyl groups
Authors: Koßmehl Gerhard , Schulz Michael , Vieth Hans‐Martin
Published: April 2003

The synthesis, characterization and liquid‐crystalline (LC) properties of polysiloxanes containing side chains with terminal 2‐fluorenyl groups and various lengths of spacers is reported. The polymers which have no flexible tail segment exhibit two smectic mesophases (SA and SE), as confirmed by polarizing microscopy, differential scanning calorimetry (DSC) and X‐ray investigations; a nematic mesophase was not found. The clearing temperatures of the polymers (in the range between 120 and 170°C) are generally 70–80°C higher than the melting temperatures of the non‐liquid‐crystalline precursors with a terminal vinyl group. With increasing spacer length the less ordered SA phase is favoured and has been found in a temperature range of up to 100 K width. For polymers with an SE phase no glass transition was detectable with DSC. The synthesized polymers are examples of the strong potential of the fluorene core to form LC phases without further structural stabilization.
Stereoblock polypropene from the Ziegler‐Natta catalyst system TiCl4/octylsodium
Authors: Busico Vincenzo , Corradini Paolo , De Biasio Rosanna , Trifuoggi Marco
Published: April 2003

Propene polymerization in the presence of the heterogeneous catalyst system TiCl4/Na‐octyl yielded polymers with unusually high molecular weights and relatively high amounts of prevailingly syndiotactic stereosequences. The characterization of such polymers proved that a fraction of the active species were able to invert their stereocontrol — from isospecific to prevailingly syndiospecific — during the growth of individual macromolecules. This suggests that, in principle, at least in conditions of limited occurrence of chain transfer reactions, the stereo‐chemical environment of the catalytically active metal in a heterogeneous Ziegler‐Natta system may not be invariant during the process of chain growth, even for the most stereospecific active species.
Sequence determination in vinyl acetate/alkyl methacrylate copolymers prepared by semicontinuous batch process by NMR spectroscopy
Authors: Kapur G. S. , Brar A. S.
Published: April 2003

Two series of copolymers, vinyl acetate/ethyl methacrylate (V/E) and vinyl acetate/butyl metha‐acrylate (V/B) copolymers, were prepared by free‐radical‐initiated emulsion copolymerization using a semicontinuous batch process. Copolymer compositions determined from 1H NMR spectroscopy were found to be in good agreement with those expected theoretically. The carbonyl and quaternary carbon resonances in 13{1H} NMR spectra were assigned to different alkyl methacrylate‐centered triad sequences by observing the changes in intensities of the resonances with copolymer composition and were used for calculating alkyl methacrylate‐centered triad fractions. The resonances giving information regarding the V‐centered triads were not properly resolved.
The structural order of some novel ionic polymers, 1. X‐ray scattering studies
Authors: Köberle Peter , Laschewsky André , Tsukruk Vladimir
Published: April 2003

A set of novel zwitterionic side‐chain polyacrylates and polymethacrylates is studied by X‐ray scattering. The structural order both in the short‐range and long‐range scale is investigated. The influence of the polymer backbone, of different locations of the ionic groups in isomeric polymers, of bound water and of added inorganic salts on the bulk structures is studied, and the observed rearrangements are analysed.
Transparent poly(vinyl alcohol) hydrogel with high water content and high strength
Authors: Cha Won‐Ill , Hyon Suong‐Hyu , Ikada Yoshito
Published: April 2003

To develop a transparent poly(vinyl alcohol) (PVA) hydrogel with high water content and high strength, we studied the physical gelation of PVA solutions and found that low temperature crystallization of PVA solutions in mixed solvents consisting of water and a water‐miscible organic solvent yields transparent gels. The strength and transparency of the PVA hydrogel is dependent on both the type of organic solvent and the mixing ratio of water/organic solvent. A mixed solvent from water/dimethyl sulfoxide resulted in the highest transparency and the highest tensile strength among the water/organic solvent combination studied. A plausible mechanism is proposed for the formation of transparent and strong hydrogels on the basis of the results obtained.
Studies on the polymerization of ethylene using a high‐yield MgCl2‐supported titanium catalyst, 2. Kinetic studies
Authors: Heller Detlef , Bilda Dieter , Fuhrmann Hans
Published: April 2003

Polymerization of ethylene was carried out in a batch process under pressure with an optimized high‐yield Ti/Mg‐catalyst. It was shown through gas chromatography analysis as well as by educt/product mass balances that no side‐reactions take place, and therefore, the monomer is quantitatively converted to polyethylene. It is demonstrated that influences of diffusion are excluded under the described experimental condition. The dependence of the overall polymerization rate on time shows that the rate at constant pressure is constant from the beginning over a certain period of time. The rate of polymerization under isobaric as well as isochoric conditions was determined to be first order with respect to monomer concentration and catalyst concentration. The overall activation energy obtained for this catalytic system was determined to be 32 kJ · mol−1.
Reversible alignment change of liquid crystals induced by photochromic molecular films, 15. Convenient methods to prepare “command surfaces” by surface‐selective modification of thin films of poly(vinyl alcohol) with azobenzene units
Authors: Aoki Koso , Seki Takahiro , Sakuragi Masako , Ichimura Kunihiro
Published: April 2003

A thin film of poly(vinyl alcohol) (PVA of different saponification degree) coated on a glass plate was subjected to a surface‐selective introduction of azobenzene moieties by treatment with a solution of 4‐(4‐hexylphenylazo) phenoxyacetyl chloride/pyridine or 4‐(4‐hexylphenylazo) phenoxybutanal /ptoluenesulfonic acid. Cells were fabricated by sandwiching a nematic liquid‐crystalline material between two surface‐modified glass plates. Alternating exposure to UV and visible light causes a reversible alignment of the liquid crystal molecules. Rubbing of the surface‐modified PVA resulted in an improved optical quality of the cell and enabled us to construct a photoresponsive twisted nematic cell. The advantages of the present method for preparing “command surfaces” are discussed from a practical point of view.
The influence of inert diluents on the structure and properties of lightly crosslinked acrylonitrile‐divinylbenzene copolymers
Authors: Wojaczyńska Maria , Kolarz Bozena N. , Hlavata Drahomira , Liesiene Jolanta , Gorbunov Aleksiej
Published: April 2003

The influence of solvents in the suspension polymerization of acrylonitrile and divinylbenzene on the structure of the resulting copolymers was tested. The solvents used were toluene or cyclohexanol in mixtures with aliphatic hydrocarbons. It was found that the solution conditions during the polymerization have no essential influence on both crystallinity and the structure of the dry copolymers. However, the properties of the copolymers differ markedly in the gel state. The copolymers obtained in the presence of good solvents show gel permeabilities and sorbabilities toward phenols several times higher than those of copolymers synthesized in the presence of poor solvents.
Synthesis and properties of aromatic polyamides derived from 2,7‐bis(4‐aminophenoxy)napthalene and aromatic dicarboxylic acids
Authors: Yang Chin‐Ping , Chen Wen‐Tung
Published: April 2003

2,7‐Bis(4‐aminophenoxy)naphthalene, a new polymer‐forming diamine, was synthesized in two steps by the preparation of 2,7‐bis(4‐nitrophenoxy)naphthalene from 2,7‐dihydroxynaphthalene and p‐chloronitrobenzene and subsequent reduction with a 10% Pd‐C catalys and hydrazine hydrate. Aromatic polyamides and copolyamides having an inherent viscosity in the range of 0,76–1,16 dL/g were prepared by the direct polycondensation of the diamine with various aromatic dicarboxylic acids or with mixed dicarboxylic acids in 1‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. Most of the polymers were soluble in aprotic solvents such as NMP and N,N‐dimethylacetamide (DMAc), and afforded transparent, flexible and tough films upon casting from DMAc solutions. Glass transition temperatures of the polymers were in the range of 246–327°C, and 10% weight loss temperatures were above 501°C in nitrogen and 476°C in air, respectively.
Synthesis of soluble p‐terphenyl‐4,4″‐ylene sulfide polymers
Authors: Kallitsis Joannis K. , Naarmann Herbert
Published: April 2003

The synthesis of substituted poly(p‐terphenyl‐4,4″‐ylene sulfide)s was carried out via nucleo‐philic displacement of the chlorine atom from 4,4″‐dichloro‐2′,3′‐disubstituted p‐terphenyls by sodium sulfide. Different aromatic groups such as phenyl, p‐methoxyphenyl, biphenylyl, phenoxyphenyl and phenylthiophenyl were used as substituents. Polymers containing sulfur near the theoretical values were obtained in most cases. The synthesized polymers are soluble in common solvents at room temperature when substituents bulkier than the phenyl group were used. Inherent viscosity values of up to 0,38 dL/g were achieved. Dynamic mechanical analysis showed that polymer films were obtained with a modulus independent of temperature up to 250°C. Thermal stability of the synthesized products was evaluated by thermogravimetry, showing that the polymers are stable up to 500°C in both air and nitrogen atmosphere. Products having a glass transition temperature in the range of 135 to 230°C, determined by differential scanning calorimetry, were obtained by this method.
Cationic polymerization of (Z)‐2‐ethoxyvinyl acetate
Authors: Wulff Günter , Birnbrich Paul
Published: April 2003

The new monomer (Z)‐2‐ethoxyvinyl acetate (5) was prepared diastereoselectively. It contains both an acetoxy and an ethoxy group on the same olefinic bond, and it was of interest to investigate its polymerization behaviour. In contrast to vinyl acetate, it can be polymerized by cationic initiation to form polymers of moderate molecular weight. The molecular weight distribution is surprisingly narrow (Mw/Mw ≈ 1,15 − 1,25)though this is not a living polymerization system. The polymerization is anticipated to proceed via a stabilized acetoxonium ion. In poly(1‐acetoxy‐2‐ethoxyethylene), (6), the acetyl group can be methanolyzed, yielding poly(1‐ethoxy‐2‐hydroxyethylene) (7), a polymer with high solubility in polar solvents.
Conductivity relaxation of neutral poly(3‐octylthiophene)
Authors: Chen Show‐An , Liao Chien‐Shiun
Published: April 2003

Dielectric relaxation (−90°C to 120°C, 0,4 Hz to 105 Hz) and ultraviolet‐visible (UV/Vis) spectroscopic (−100°C to 200°C) measurements for poly(3‐octylthiophene) were carried out. A correlation of complex electric moduli, which were converted from dielectric measurements, with thermal transitions from UV/Vis and dynamic mechanical analysis indicates (i) no significant effect of side‐chain motion on charge transport; (ii) in the glass transition and rubbery regions relaxation time distribution becomes broadened with temperature; (iii) as the coplanar subchains in the order region melt, the relaxation time distribution becomes more narrow.
Azide function and polyaddition: reaction of 2‐azido‐2,4,4‐trimethylpentane and monoazidopoly(2‐methylpropene) with some dienophiles
Authors: Nguyen Hung Anh , Cheradame Hervé , Maréchal Ernest
Published: April 2003

The 1,3‐dipolar addition of 2‐azido‐2,4,4‐trimethylpentane (1) to acetylene and ethylene derivatives such as phenylacetylene (2), acrylonitrile, diphenyl fumarate (4) and N,N′‐methylenebis(1,4‐phenylene)dimaleimide (8) leads to the corresponding triazole and triazoline derivatives. This study demonstrates that tertiary azides are able to react with dienophiles, and the application of this reaction for the synthesis of block copolymers was investigated with monoazido‐telechelic poly(2‐methylpropene) (PMP). It was shown that the azido group is stable under the severe conditions of the polycondensation reaction without decomposition (170°C, 24 h), and the monoadduct PMP‐8 is produced with acceptable yield.