bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and properties of two new series of isomeric liquid crystalline polyesters with conjugated double bonds
Authors: Navarro Fernando , Serrano José Luis
Published: April 2003

Two homologous series of flexible main chain liquid crystalline polyesters with isomeric mesogenic groups containing conjugated double bonds, were synthesized and studied by differential scanning calorimetry and optical microscopy. One series (S1) has the p‐phenylene‐diacryloyloxydibenzoyl moiety as a mesogenic unit. The other (S2) has the terephtaloyl dioxydicinnamoyl moiety as a mesogenic unit. The reactivity of the conjugated double bonds of the p‐phenylenediacryloxy unit, at the temperature of mesophase formation, impedes the stability of liquid crystalline mesophases of polymers of series (S1). Two low molecular weight analogues of polymers were also prepared and their properties compared with those of polymers of similar structure. The two model compounds form stable smectic mesophases over a wide range of temperatures, which shows the high mesomorphogenic ability of both mesogenic units.
Core‐shell type polymer microspheres prepared by domain fixing of block copolymer films
Authors: Ishizu Koji , Onen Aysen
Published: April 2003

Well‐defined poly[styrene(S)‐b‐isoprene(I)] diblock copolymers were prepared by sequential anionic addition. The crosslinking reactions of polyisoprene (PI) spherical domains of these block copolymers were carried out in a n‐hexane solution of sulfur monochloride (S2Cl2). Electron micrograph of crosslinked products indicates the structure of core‐shell type polymer microspheres. It is found from NMR and turbi+imetric measurements that the solubility of core‐shell type polymer microspheres depends strongly on that of block chains comprising the shell portion. The particle size of these microspheres shows a narrow distribution.
Silyl enol ethers as monomer. I. Radical copolymerizability of α‐trimethylsilyloxystyrene
Authors: Nagai Katsutoshi , Asada Keisuke , Chiba Keiji , Kuramoto Noriyuki
Published: April 2003

α‐Trimethylsilyloxystyrene (TMSST), the silyl enol ether of acetophenone, was not homopolymerized either by a radical or a cationic initiator. Radical copolymerization of TMSST with styrene (ST) and acrylonitrile (AN) in bulk and the terpolymerization of TMSST, ST, and maleic anhydride (MA) in dioxane were studied at 60°C and the polymerization parameters of TMSST were estimated. The rate of copolymerization decreased with increased amounts of TMSST for both systems. Monomer reactivity ratios were found as follows: r1 = 1.48 and r2 = 0 for the ST (M1)–TMSST (M2) system and r1 = 0.050 and r2 = 0 for the AN (M1)–TMSST (M2) system. The terpolymerization of ST (M1), TMSST (M2), and MA (M3) gave a terpolymer containing ca. 50 mol % of MA units with a varying ratio of TMSST to ST units and the ratio of rate constants of propagation, k32/k31, was found to be 0.39. Q and e values of TMSST were determined using the values shown above to be 0.88 and −1.13, respectively. Attempted desilylation by an acid catalyst for the copolymer of TMSST with ST afforded polystyrene partially substituted with hydroxyl groups at the α‐position.
Hydrophobic interactions in the enantioselective solvolyses of optically active activated esters by imidazole‐containing polymeric surfactants
Authors: Cho Iwhan , Lee Burm‐Jong
Published: April 2003

Enantioselective solvolyses of optically active activated esters in the aggregate system of optically active polymeric surfactants containing imidazole and benzene moieties were performed. The catalyst polymers [copoly(MHis‐DEVAB)] employed were copolymers of N‐methacryloyl‐L‐histidine methyl ester (MHis) with N,N‐dimethyl‐N‐hexadecyl‐N‐[10‐(p‐vinylcarboxanilido) decyl]ammonium bromide(DEVAB). In the solvolyses of N‐carbobenzoxy‐D‐ and L‐phenylalanine p‐nitrophenyl esters (D‐NBP and L‐NBP) by polymeric catalysts, copoly(MHis‐DEVAB) exhibited not only increased catalytic activity but also enhanced enantioselectivity as the mole percent of surfactant monomers in the copolymers increased. The polymeric catalysts showed noticeable enantioselective solvolyses toward D‐ and L‐NBP of the substrates employed. As the reaction temperature was lowered for the solvolyses of D‐ and L‐NBP with the catalyst polymer containing 4.8 mol% of MHis, an increased reaction rate and enhanced enantioselectivity were observed. The coaggregate systems of the polymer and monomeric surfactants were also investigated. The case of a coaggregate system consisting of 70 mol% of cetyldimethylethylammonium bromide with polymeric catalyst showed maximum enantioselective catalysis, viz., kcat (L)/kcat(D) = 6.68. The catalyst polymers in the sonicated solvolytic solutions were confirmed to form large ordered aggregate structure by electron microscopic observation. From these results, it is concluded that hydrophobic interaction in ordered aggregate structure plays an important role in enantioselective catalysis of optically active imidazole‐containing polymers.
Study of interaction between two oppositely charged polyelectrolytes and formation of polyelectrolyte complexes
Authors: Chatterjee S. K. , Yadav D. , Ghosh Sudipta , Khan A. M.
Published: April 2003

Polyelectrolyte complex formation has been studied between oppositely charged polyelectrolytes, e.g., polyethylene‐imine, polymethacrylic acid, and methacrylic acid–methacrylamide copolymer. Formation of complexes could be shown through several experimental techniques, e.g., viscometry, conductometry, potentiometry, and IR spectra. It is suggested that these complexes are perhaps formed as a result of electrostatic cooperative interaction and a “ladder‐like” interaction is likely to be more favorable.
Evidence of formation of radicals in the polystyrene thermodegradation
Authors: Carniti P. , Gervasini A. , Beltrame P. L. , Audisio G.
Published: April 2003

The formation of radicals in the thermal degradation of polystyrene (PS) in tubes sealed under vacuum has been evidenced by using ESR spectroscopy. The radicals were found to be stable for weeks at room temperature. The rate coefficients of the formation of radicals have been evaluated in the temperature range 350–420°C. The reaction kinetically followed has been related to the initiation step of the multi‐step degradation process of PS. The activation energy of this reaction resulted 185 kJ/mol.
Electroinitiated polymerization of acrylamide by direct electron transfer
Authors: Hacioglu B. , Akbulut U. , Toppare L.
Published: April 2003

Electroinitiated polymerization of acrylamide was carried out in acetonitrile–tetrabutylammonium fluoroborate by electrolytic reduction of monomer. It was shown by cyclic voltammetry that direct electron transfer from the cathode to the monomer can be achieved in this solvent–electrolyte system. Reduction peak potentials measured by cyclic voltammetry indicated that sodium salts will interfere with such a mechanism. Since the reduction peak potential of sodium salt and dimethylformamide are found to be lower than acrylamide, this couple was not employed for polymerization in this work. Acetonitrile–tetrabutylammonium fluoroborate couple is stable at the reduction peak potential of acrylamide.
Preparation and characterization of thin films of monomeric and polymeric octacyanophthalocyanines
Authors: Ashida Michio , Ueda Yasukiyo , Yanagi Hisao , Sayo Koichi
Published: April 2003

Thin films were prepared on substrates, cleavage surface of KCl single crystal, and metallic copper, by reaction of 1,2,4,5‐tetracyanobenzene with the substrate at various temperatures. The films were characterized by elemental analysis, IR, and UV/VIS spectroscopies. The films were observed by scanning electron microscopy. The films produced on copper at temperatures between 300 and 400°C consisted of copper octacyanophthalocyanine and its polymer with ladder structure. The ratio of polymer to monomer increased with elevating the reaction temperature. The films were composed of ribbon‐like crystals. The film produced on copper above 450°C was composed of an amorphous and continuous layer of polymeric copper phthalocyanine. The film produced on KCl at temperatures between 250 and 350°C consisted of potassium octacyanophthalocyanine and its polymer with ladder structure. The film produced on KCl above 450°C was polymeric potassium phthalocyanine. Those films contained more metal content than that required stoichiometrical.
Radical desorption in emulsion polymerization
Authors: Asua J. M. , Sudol E. D. , El‐Aasser M. S.
Published: April 2003

The derivation of a radical desorption coefficient in emulsion polymerization is presented, which takes into account the possible reactions of the desorbed radical in the aqueous phase as well as the competition between desorption and termination in polymer particles containing more than one radical. This model overcomes some important limitations of the previous models and is able to explain previously reported experimental results that the other models were unable to explain.
Acetylene–norbornene copolymers
Authors: Ramakrishnan S. , Hirsch J. A. , Martinez J. R. , Chien J. C. W.
Published: April 2003

Metathesis ring opening polymerization has been used to copolymerize norbornene and 7,8‐bis(trifluoromethyl)tricyclo[4,2,2,02,5]deca‐3,7,9‐triene. Subsequent thermal elimination of the precursor copolymers yielded acetylene–norbornene copolymers. The undoped copolymers were found to have electrical conductivity, spin concentration, and EPR linewidths which vary with composition. The location of the trans‐CH out‐of‐plane vibration, however, was invariant at 1010cm−1 indicating that conjugation length of n > 4 are present even at 40% acetylene content in the copolymer. The copolymers containing 79 mol % of acetylene units attained a doped conductivity of 0.02 S/cm with a dopant concentration of 6 mol % of I per sp2 carbon.
Aqueous polymerization on clay surfaces. III. The polymerization of methyl methacrylate by montmorillonite/thiourea initiating system
Authors: Bhattacharya J. , Chakravarti S. K. , Talapatra S. , Saha S. K. , Guhaniyogi S. C.
Published: April 2003

Initiation of polymerization of methyl methacrylate with redox system montmorillonite (with lattice Fe3+)–thiourea has been achieved. The rates are dependent on both clay mineral and thiourea. Amidosulfenyl radicals are believed to initiate the polymerization on the clay surface. The polymerization produced nonextractable clay–polymer adduct up to an extent of 70 wt %. The pH of the medium (in the acidic range) did not affect the polymerization rate.
Synthesis of polynucleotide analogs by grafting optically active adenine, cytosine, and hypoxanthine derivatives onto polytrimethylenimine
Authors: Overberger C. G. , Chang Ji Young
Published: April 2003

A new family of polynucleotide analogs were prepared by grafting nucleic acid base derivatives onto polytrimethylenimine. Several new optically pure α‐nucleic acid base substituted propanoic acids were prepared as pendant groups. The (R)‐ethyl adeninylpropanoate was obtained from adenine and (S)‐ethyl lactate by utilizing a diethyl azodicarboxylate‐triphenyl phosphine method. Subsequent hydrolysis of the ester in aqueous acid gave the (R)‐adeninylpropanoic acid without racemization. The reaction of cytosine sodium salt with (S)‐ethyl 2‐[(methylsulfonyl)oxy] propanoate produced the 20% racemized (R)‐ethyl 2‐(cytosin‐1‐yl)propanoate. The optically pure ester was obtained by recrystallization from ethyl alcohol, which was hydrolyzed in aqueous acid to give the (R)‐acid with 66% enantiomeric excess. The (R)‐2‐(hypoxanthin‐9‐yl)propanoic acid was prepared by reaction of (R)‐2‐(adenin‐9‐yl)propanoic acid with sodium nitrite. The pendant groups were allowed to react with N‐hydroxy compounds in the presence of dicyclohexylcarbodiimide to give the active esters. These active esters underwent reaction with N,N‐dipropylamine to provide monomer model compounds. The pendant groups were grafted onto polytrimethylenimine by using the active ester method. The racemization reactions were observed in the grafting reactions. The resulting polymers showed a range of percent grafting from 60 to 80%.
Photocrosslinking of polyethylene. II. Properties of photocrosslinked polyethylene
Authors: Chen Yong Lie , Rånby Bengt
Published: April 2003

Some properties of photocrosslinked high density polyethylene (2 mm thick sheets) have been studied. The homogeneity of the network is greatly improved by the application of triallylcyanurate (TAC) as crosslinking agent. The role of TAC in promoting the crosslinking is discussed. The crosslinked PE is found to be durable towards immersion in boiling water. Oxygen permeability increases while density and melting point decrease with increasing degree of crosslinking. The network chain density is obtained using conventional swelling method in boiling xylene, which together with data from melting point depression show that contribution of chain entanglement is insignificant to the gel formation of PE in this work.
Terpolymerization of maleic anhydride with vinyl monomers
Authors: Florjańczyk Zbigniew , Krawiec Włodzimierz
Published: April 2003

The relative reactivity of vinyl monomers characterized by electron donor and electron acceptor properties in free radical terpolymerization with maleic anhydride has been compared on the basis of product composition analysis. Terpolymers containing ca. 50 mol % of maleic anhydride were obtained in systems containing two electron donor monomers and the relative reactivity of them increases in the following order: 1‐hexene < propylene ≈ isobutylene < styrene < isoprene < 1,3‐butadiene. In systems consisting of an electron donor monomer and two electron acceptor monomers (i.e., maleic anhydride and an acrylic monomer), the composition of the terpolymers formed depends essentially on the resonance stabilization of the electron donor monomer. With a rise of their resonance stabilization, the content of acrylic monomeric units decreases and the share of alternating sequences of the electron donor and maleic anhydride monomeric units increases. It was found that the relative reactivity of maleic anhydride in all such systems is much greater than that predicted on the basis of reactivity ratios determined in binary systems. The relative reactivity of the studied acrylic monomers decreases in the order: methyl methacrylate > methyl acrylate > acrylonitrile. In the presence of catalytic amounts of ZnCl2 the content of acrylic monomeric units clearly increases in the products obtained, mainly as a result of homopropagation. The results obtained are discussed in terms of the classical mechanism of propagation and the complex participation model.
Dynamic mechanical and dielectric properties of epoxidized SBS triblock copolymer
Authors: Hsiue Ging‐Ho , Huang Wen‐Kuei , Hou Wei‐Hsin
Published: April 2003

The morphological and dynamic properties of epoxidized styrene–butadiene–styrene block copolymers were studied and compared with their parent styrene–butadiene–styrene block copolymer (SBS). Two peaks were observed in the mechanical loss (tan δ) curve which can be attributed to segmental motion of epoxidized polybutadiene (EPPB) and polystyrene. Analysis by DSC thermograms also showed the linear increase of glass transition temperature for EPPB domain with the epoxy group content. Phase separated structures of epoxidized SBS as observed by TEM suggests a considerable degree of mixing occurred between phases after 80 mol % of the double bonds in SBS were epoxidized. The interfacial region displays a third peak and causes much steeper drop in modulus at higher temperature than Tg of EPPB. Parallel dielectric relaxation measurements were also made in the frequency range of 30 Hz–1 KHz as a function of temperature. In each dielectric constant (ϵ′) curve, there is a maximum near the Tg of EPPB determined from the dielectric loss tangent curve. The shift in Tg of EPPB versus epoxy group content was consistent with that measured by the thermal and dynamic mechanic analysis. These findings indicated an 8°C shift in glass transition temperature as the epoxy group content in EPPB increased 10%.
Anionic syntheses of terminally functionalized ethylene oligomers
Authors: Bergbreiter David E. , Blanton J. R. , Chandran R. , Hein M. D. , Huang K.‐J. , Treadwell D. R. , Walker S. A.
Published: April 2003

Synthetic procedures for preparation of terminally functionalized linear ethylene oligomers are described. The preferred synthetic method is anionic oligomerization of ethylene with n‐butyllithium–tetramethylethylenediamine and electrophilic substitution of the living oligomer so‐formed. Conditions and procedures for subsequent chemistry to elaborate the end groups of these oligomers are described. These procedures afford strictly linear ethylene oligomers which contain a wide variety of end groups and which range in molecular weight from 1000 to 4500 (Mn). The product oligomers were characterized spectroscopically as toluene‐d8 solutions at 110°C using multinuclear NMR, FT‐IR, fluorescence, and UV‐visible spectroscopies as appropriate. Alternative stepwise approaches to such oligomers are also discussed.
Kinetic analysis of the transesterification of dimethyl terephthalate with ethylene glycol in a semibatch reactor
Authors: Barandiarán M. J. , Asúa J. M.
Published: April 2003

The kinetic analysis of the transesterification of ethylene glycol (EG) and dimethyl terephthalate (DMT) was studied in a semibatch reactor under nonisothermal conditions. The effect of the temperature profile, EG/DMT ratio, and catalyst concentration on the reaction rate was studied. Models were fitted by using an algorithm of parameter estimation in differential equations based on the Gauss–Newton method improved with the Marquardt extension. It was found that, unlike previous authors, the reaction rate was not a classical third order reaction of first order with respect to EG, DMT, and catalyst concentration, but the EG reaction order was 0.6 and a hyperbolic function was found to fit the relationship between reaction rate and catalyst concentration. Also, it was found that, at high conversions, the effect of the reverse reaction should not be neglected.
Synthesis and characterization of acetylene‐terminated aromatic amide resin precursors
Authors: Abraham Tonson , Soloski Edward J. , Benner Charles L. , Evers Robert C.
Published: April 2003

A series of 10 acetylene‐terminated aromatic amide monomers was synthesized by the triethylamine‐promoted reaction of bis[p‐(m‐chlorocarbonylphenoxy)phenyl] sulfone or bis[p‐(m‐chlorocarbonylphenoxyl)phenyl]ketone witho‐ orp‐ethynyl‐ ando‐ orp‐trimethylsilylethynylaniline. Yields were essentially quantitative. Structures were verified by infrared and nuclear magnetic resonance spectroscopy and mass spectral data. Thermal characteristics of the monomers were investigated by means of differential scanning calorimetry and thermogravimetric analysis. The initial glass transition temperatures were generally well below the onset of cure which occurred in the 160–225°C range for the terminal ethynyl monomers and in the 260–295°C range for their trimethylsilylethynyl analogs. Onset of decomposition in air for the resinified terminal ethynyl monomers took place in the 400–485°C range, while resins from the trimethylsilylethynyl monomers underwent breakdown at substantially lower temperatures.
Syntheses and crosslinking reactions of polymers containing spiroorthoester moieties
Authors: Tagoshi Hirotaka , Endo Takeshi
Published: April 2003

The radical copolymerization of unsaturated spiroorthoesters such as 2‐methylene‐1,4,6‐trioxaspiro[4.6]undecane (SOE I) and 2‐methylene‐9‐methyl‐1,4,6‐trioxaspiro[4,5]decane (SOE II) with vinyl monomers was carried out to find that SOE I and SOE II were copolymerized with electron‐poor olefins such as methyl acrylate, acrylonitrile, and methyl methacrylate to obtain the corresponding copolymers containing spiroorthoester moieties, respectively. The obtained copolymers were treated with BF3.OEt2 or BzS+SbF to afford crosslinked polymers undergoing expansion in volume on crosslinking in those cases of copolymers of SOE I.
Preparation of cationic polyacrylamides by a modified Hofmann reaction: Fluorescent labeling of cationic polyacrylamides
Authors: Tanaka Hiroo , Ödberg Lars
Published: April 2003

Cationic polyacrylamides (C‐PAM) which contain both primary and quaternary amines were prepared according to the Hofmann reaction by adding choline chloride to a solution of polyacrylamide in water. The reaction was 90% complete after 60 min at 20°C. The degree of amination was over 70% and the proportion of primary and quaternary amines could be altered widely by controlling the relative concentrations of NaOH, NaOCl, and choline chloride.

C‐PAM was dansylated (fluorescently labeled) in a homogeneous system using aqueous dimethylformamide as solvent. The optimum excitation wavelength for dansylated C‐PAM in water at room temperature (22 ± 1°C) was 333 nm and the corresponding emission wavelength 538 nm. The fluorescence intensity was almost constant at pH levels above 5, but decreased rapidly below pH 4 and was almost zero at pH 2.
Polymers from multifunctional isocyanates. II. Synthesis and polyaddition reactions of novel aliphatic diisocyanatoesters
Authors: Mormann Werner , Leukel Gabriele
Published: April 2003

Trimethylsiloxyalkyl and ‐aryl isocyanates were reacted with alkanedioic acid dichlorides (oxalyl‐, adipoyl‐, suberoyl dichloride) or isocyanatoalkanoyl chlorides (3‐isocyanatopropanoyl‐, 6‐isocyanatohexanoyl chloride) to give liquid low viscous diisocyanatoesters and ‐diesters in high yield. From these and 1,4‐butanediol, polyurethanes were made having a regular sequence of ester and urethane groups. The properties of the polymers, especially their thermal stability, are discussed with respect to their structure. They are mostly crystalline materials (mp 100–240°C). Thermogravimetry data indicate that polyurethanes based on diisocyanatoalkyl oxalates decompose 50–80°C lower than those based on other acids.
Thermal analysis of chemically synthesized polyaniline and effects of thermal aging on conductivity
Authors: Wei Yen , Hsueh Kesyin F.
Published: April 2003

Thermal characteristics of chemically synthesized polyaniline with various dopants have been studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy, gel‐permeation chromatography (GPC), and chemical titration. The HCl‐doped polyaniline shows three major weight losses at around 100, 200, and 500°C which are assigned to removal of H2O and HCl, and decomposition of the polymer, respectively. Thermal aging of the HCl‐doped polyaniline performed at 100, 150, and 200°C for various periods of time results in a decrease in conductivity. After the thermal treatments, the polymer can be re‐doped with HCl to partially recover the conductivity. However, both the conductivity and the doping level cannot be restored to the level of the original materials owing probably to changes in morphology, crosslinking, or other chemical reactions.
Preparation and radical ring‐opening polymerization of 2‐substituted‐4‐methylene‐1,3‐dioxolanes
Authors: Hiraguri Yoichi , Endo Takeshi
Published: April 2003

2‐Methyl‐2‐phenyl‐4‐methylene‐1,3‐dioxolane (IIa), 2‐ethyl‐2‐phenyl‐4‐methylene‐1,3‐dioxolane (IIb), 2‐phenyl‐2‐(n‐propyl)‐4‐methylene‐1,3‐dioxolane (IIc), 2‐phenyl‐2‐(i‐propyl)‐4‐methylene‐1,3‐dioxolane (IId), 2‐(n‐heptyl)‐2‐phenyl‐4‐methylene‐1,3‐dioxolane (IIe), 2‐methyl‐2‐(2‐naphthyl)‐4‐methylene‐1,3‐dioxolane (IIf), and 2,2‐diphenyl‐4‐methylene‐1,3‐dioxolane (IIg) were prepared and polymerized in the presence of a radical initiator. IIa–IIf were found to undergo vinyl polymerization with ring‐opening reaction accompanying the elimination of ketone groups in bulk. IIg was found to undergo the quantitative ring‐opening reaction accompanying the elimination of benzophenone in solution to obtain polyketone without any side reaction.
Synthesis of crown ether‐terminated poly(methyl methacrylate) by radical chain transfer polymerization
Authors: Chujo Yoshiki , Nakamura Tetsuya , Yamashita Yuya
Published: April 2003

Mercapto‐16‐crown‐5 was prepared starting from tetraethyleneglycol and 3‐chloro‐2‐chloromethyl‐1‐propene. Radical polymerization of methyl methacrylate was carried out in the presence of mercapto‐16‐crown‐5 as a chain transfer agent to give crown ether‐terminated poly(methyl methacrylate). The end crown group was characterized by IR and 1H‐NMR spectra. Sodium cation was selectively extracted by this crown‐containing polymer. The molecular weight of the obtained polymer had influence upon the ability of extraction of sodium cation.
Photoresponsive peptide and polypeptide systems. VIII. Synthesis and reversible photochromism of azo aromatic poly(L‐ornithine)
Authors: Yamamoto Hiroyuki , Nishida Ayako , Takimoto Tomoyuki , Nagai Akira
Published: April 2003

Poly(L‐ornithine) having azo aromatic side chain was synthesized by the water‐soluble carbodiimide procedure. The photochemical properties of the azo polypeptide poly[Nδ‐p‐(phenylazo)benzoyl‐L‐ornithine] (PPABLO) was investigated by absorption and circular dichroism spectroscopy in hexafluoro‐2‐propanol (HFIP). The photochromism of the dichroic bands in the visible and ultraviolet wavelength regions was found to be reversible as a function of irradiation time at different wavelengths due to the photostationary state (about 70% trans)–cis photoisomerization of the azo aromatic moieties. The reversible photoinduced solubility change was also studied. On irradiation PPABLO is soluble under ultraviolet light (cis) and precipitate under visible light (70% trans) in HFIP–water. A discussion was presented that includes results on azo aromatic poly(L‐lysine).
Emulsifier‐free emulsion copolymerization of styrene and butyl acrylate. III. Kinetic studies in the presence of a surface active comonomer, the sodium acrylamido undecanoate
Authors: Guillaume J. L. , Pichot C. , Guillot J.
Published: April 2003

Emulsion terpolymerization of styrene (S), butylacrylate (BuA) and sodium acrylamido undecanoate (AUNa), a surface active functional monomer have been carried out using a batch process in the presence of sodium 4‐4′‐azobiscyanopentanoate as initiator. Varying the AUNa concentration, stable particles bearing only carboxylic charges have been produced with diameters ranging from 200 to 500 nm at solids content as high as 40%. However a low AUNa yield at the particle surface has been found (30–35%), which could be explained by very unfavorable reactivity ratios of AUNa with S and BuA. Most of the AUNa seems to be wasted in the water phase (unpolymerized and forming hydrosoluble chains). Furthermore, a concentration of AUNa higher than 10−2 mol L−1 results in the latex destabilization, presumably caused by the formation of a large amount of polyelectrolytes. Kinetic studies of the AUNa consumption show that the AUNa is mainly fixed at the particle surface between 90 and 100% conversion, which indicates that the AUNa is mainly polymerized in the water phase and not at the particle surface. An attempt has been made to increase the surface charge density by polymerizing a shell of AUNa/S/BuA on a seed latex. It turned out to be unsuccessful (low surface yield, formation of new particles).
Anionic polymerization of N‐substituted maleimide. V. A study on the kinetic features of anionic polymerization of N‐phenylmaleimide
Authors: Hagiwara Tokio , Shimizu Takamasa , Uda Tomonori , Hamana Hiroshi , Narita Tadashi
Published: April 2003

The kinetic feature of the anionic polymerization of N‐PMI was investigated in THF. The polymerization system initiated with lithium tert‐butoxide was revealed to be so‐called “slow‐initiation” system. The rate constant of the initiation reaction, ki, was obtained to be 4.2 × 10−3 (L mol−1 s−1) at −72°C. The apparent rate constants of the propagation reaction, k, at −72°C were individually obtained from each slope of the first‐order plots in the later stages of the polymerizations for four different initiator concentrations. Each k is fairly close to that of initiation rate around 10−3. The propagation reaction was concluded to be dominated by ion‐pair mechanism from the analysis of the kinetic data and the results of the addition effects of crown ether and common salt.
Thermotropic liquid crystalline polymers with low thermal transitions. I. Low melting thermotropic liquid crystalline homo‐ and co‐polycarbonates
Authors: Mahabadi Hadi‐Kh , Alexandru Lupu
Published: April 2003

Due to the particular rheological properties of thermotropic liquid crystalline polymers (TLCP), their application for imaging technology has been investigated. The first class of polymers investigated in this study are the thermotropic liquid crystalline polycarbonates prepared from the solution polycondensation of p,p‐dihydroxybiphenyl with bischloroformate as the aliphatic flexible spacer. From the variety of bischloroformates employed, smectic TLCP's were generally obtained with the possible presence of a nematic mesostate. The introduction of comonomers such as substituted hydroquinones or bisphenols were found to lower both the melting transitions and mesophasic range of the TLCP. From rheological characterization, the amount of nonmesogenic moieties present in the copolycarbonates were found to correlate with the increase in the melt viscosity of TLCP.
Thermotropic homopolyester. I. Synthesis and characterization of homopolyesters containing the mesogenic unit, bicyclo[2.2.2]oct‐2‐ene
Authors: Harruna Issifu I. , Polk Malcolm B.
Published: April 2003

Homopolyesters based on bicyclo[2.2.2]oct‐2‐ene as a mesogenic group were prepared and characterized. The use of bicyclo[2.2.2]oct‐2‐ene in these homopolyesters lowered the symmetry of the resulting systems enough to lead to the observation of melting behavior.
Synthesis and radical copolymerization of new type pyridinum monomer and redox behavior of its polymers
Authors: Kitamura Naoya , Nambu Yoko , Endo Takeshi
Published: April 2003

A new type pyridinium salt monomer, 1‐vinyl‐4‐carbamidopyridinium perchlorate, was prepared, and then homopolymerized and copolymerized with methyl methacrylate (MMA), 2‐hydroxyethyl methacrylate (HEMA), styrene, and acrylonitrile. Redox potentials of these pyridinium salt monomer and polymers were more positive than that of the model compound (1‐methyl‐4‐carbamidopyridinium salt). The copolymer with MMA showed an interesting redox behavior.
High molecular weight aromatic polymers by nickel coupling of aryl polychlorides
Authors: Colon I. , Kwiatkowski G. T.
Published: April 2003

This paper describes a totally new method for the formation of high molecular weight aromatic polymers. High molecular weight polyarylethersulfones are produced by nickel catalyzed coupling of aryl dichloride monomers. Metallic zinc is used to drive the polymerization reaction which takes place under relatively mild conditions in the presence of triphenylphosphine and a dipolar aprotic solvent. The versatility of the reaction is demonstrated, as well as the ability to provide a variety of high temperature polymers from readily available and inexpensive monomers. It is possible to use an integrated two‐step process to produce aryl dichlorides from inexpensive aryl chlorides, and then to couple these directly to polymer without need for isolation and purification. This process resulted from a fundamental understanding of the chemistry and the use of statistically designed experiments to identify the important reaction parameters and to optimize the degree of polymerization.
Crystallization of poly(ethylene oxide) in binary polymer blends: Influence of tacticity of poly(methyl methacrylate)
Authors: John Eunsook , Ree Taikyue
Published: April 2003

Kinetics of the crystallization of poly(ethylene oxide) (PEO) from the PEO blends with syndiotactic, atactic, or isotactic poly(methyl methacrylate) (s‐, a‐, and i‐PMMA) was investigated. The isothermal spherulitic growth rates were measured with an optical microscope. The influence of the composition of the blends, the tacticity of PMMA, and temperature on the growth rates were studied. Linear growth rates were observed regardless of the tacticity. The growth rates of spherulites are markedly reduced by a‐PMMA and s‐PMMA. However the growth rates of PEO are hardly influenced by i‐PMMA. Such observations are interpreted by assuming that PEO forms miscible blends with a‐ and s‐PMMA in the molten states, whereas it does not from with i‐PMMA.
Synthesis and characterization of side‐chain liquid crystalline polysiloxanes containing oligooxyethylene spacers and benzyl ether based mesogenic groups
Authors: Hsieh Chang‐Jyh , Hsu Chain‐Shu , Hsiue Ging‐Ho , Percec Virgil
Published: April 2003

The synthesis of side‐chain liquid crystalline polysiloxanes containing oligooxyethylene spacers and 4‐methoxyphenyl benzyl ether and 6‐cyano‐2‐naphthyl benzyl ether based mesogenic groups is presented. The phase behavior of both monomeric and polymeric liquid crystals was characterized by differential scanning calorimetry and optical polarized microscopy. All synthesized polysiloxanes present smectic mesomorphism. The insertion of oxygen atoms into the flexible aliphatic spacers leads to decrease in both glass transition and isotropization temperatures of the resulting side‐chain liquid crystalline polymers.
The synthesis, characterization, and photoinitiated cationic polymerization of silicon‐containing epoxy resins
Authors: Crivello J. V. , Lee J. L.
Published: April 2003

The preparation of a variety of silicon‐containing epoxy monomers and oligomers is described and their reactivity in photoinitiated cationic polymerization examined. Monomers and oligomers having terminal cycloaliphatic epoxy groups were found to be especially reactive in cationic polymerization. These materials are attractive candidates for use in coatings, adhesives, and elastomers.
In situ formation of new crosslinking agents from acrylate derivatives and bisepoxides
Authors: Lee Soo , Thames Shelby F. , Mathias Lon J.
Published: April 2003

The synthesis of several newly available diacrylate crosslinking agents derived from hydroxy functional acrylates and bisepoxides is described. These crosslinking agents are synthesized via the acid catalyzed addition of hydroxyl‐containing acrylate monomers to bisepoxides derived from bisphenol‐A and its hexafluoropropyl analog. These materials are generated in an excess of the acrylate monomer and the reaction mixtures are then converted directly to highly crosslinked materials. The alcohol functional monomers include hydroxyethyl methacrylate (HEMA) and the butyl and ethyl esters of (α‐hydroxymethyl)acrylic acid. The latter are especially interesting for several reasons. First, they are readily available through the addition of the corresponding acrylate to formaldehyde. Second, these monomers react with the bisepoxides to give all‐ether‐linked connecting groups, in conrast to HEMA which yields a molecule with both ether and ester linkages between the two acrylate units. Third, the monomers are very different in solubility from HEMA and the polymers display very different chemical and physical properties. For example, while the crosslinked HEMA polymers are swellable in water, those of the (α‐hydroxymethyl)acrylates are insoluble in water but swellable in organic solvents such as chloroform. All monomers, crosslinking agents, and crosslinked polymers were characterized by FT‐IR, solution or solid state 13C‐NMR spectroscopy, and thermal analysis.
New gem‐dicyanocyclobutane‐containing hydroxyesters
Authors: Mori Shoji , Kakuchi Toyoji , Padias Anne Buyle , Hall H. K.
Published: April 2003

Six new gem‐dicyanocyclobutanes containing carbomethoxy and hydroxyl/acetoxy functions were synthesized by cycloaddition of the appropriate vinyl ethers or alkoxystyrenes to methyl β,β‐dicyanoacrylate. They proved to be too thermally labile to allow polycondensation to potentially piezoelectric linear polyesters.
The polymerization of oxiranes with the α‐chlorobenzyl methyl sulfide–antimony pentachloride initiator system
Authors: Iijima Takao , Kakiuchi Hiroshi
Published: April 2003

α‐Thiomethoxyphenylmethylium hexachloroantimonate was prepared from α‐chlorobenzyl methyl sulfide and antimony pentachloride and studied by visible spectroscopy. The salt is unstable at room temperature and used as in situ initiator for the polymerization of oxiranes in dichloromethane. Propylene oxide (PO) and cyclohexene oxide (CHO) were used as oxiranes. The microstructure of PO polymer is amorphous by 13C‐NMR. The initiator was more effective for the polymerization of CHO than for that of PO.
Model reactions of functionalization of polycarbonate. Reactions of phenyl chloroformate with nucleophiles and cationic polymerization behavior of bicyclo orthoesters containing carbonate group
Authors: Uno Hitomi , Nakazawa Akihiko , Takata Toshikazu , Endo Takeshi
Published: April 2003

Some model experiments for functionalization of a polycarbonate were carried out. At first, reactivity of phenyl chloroformate with a few nucleophiles was examined. Reaction with alkyl amines gave corresponding carbamates, but in the case of aniline, formation of a byproduct diarylurea was observed. Reactions with alcohols and phenols afforded carbonates in moderate yields, in which p‐nitrophenol and isopropyl alcohol were less reactive. On the basis of these results, 1‐ethyl‐4‐phenoxycarboxymethyl‐2,6,7‐trioxabicyclo[2.2.2]octane (2) and 1‐ethyl‐4‐ethoxycarboxymethyl‐2,6,7‐trioxabicyclo[2.2.2]octane (3) were prepared by the reaction of phenyl and ethyl chloroformates with 1‐ethyl‐4‐hydroxymethyl‐2,6,7‐trioxabicyclo[2.2.2]octane in the presence of tert‐amine. 2 polymerized cationically with BF3OEt2 at more than 80°C to give a polyether containing both ester and carbonate groups in the side chain, with contamination of a gelled polymer.
Lanthanide–imidazole complexes as latent curing agents for epoxy resins
Authors: Kaplan M. L. , Wayda A. L. , Lyons A. M.
Published: April 2003

Imidazoles have for some time been recognized as curing agents for epoxy resins. Once the resin and the imidazole compound are mixed there is a relatively short time in which the mixture can be used, since the polymerization (curing) reaction occurs to some extent even at room temperature causing the reaction mixture to thicken. In order to circumvent this problem we have found that imidazoles can be complexed with organo‐lanthanide compounds thereby tying up the imidazole and retarding its rate of reaction in the cure of epoxy materials at ambient temperatures. When it is desired to enhance the rate of cure the temperature of the mixture is simply raised. This paper concerns studies of the epoxy cure reaction with the M(THD)3–IM series. M represents the lanthanide metals Eu, Ho, Pr, Dy, Yb, and Gd, and THD is 2,2,6,6‐tetramethyl‐3,5‐heptanedione. Cure reactions were followed by differential scanning calorimetry and in some cases by infrared spectroscopy. We have demonstrated that these organo‐lanthanide–imidazole complexes are effective thermally latent curing agents for epoxy resins. At a temperature of 150°C cure is quite rapid. In the course of these studies it has also been determined that there is an inverse correlation between the lanthanide ionic radius in the complex and the temperature at which the cure reaction occurs. Thus the Yb compound, where the imidazole is most strongly bound, cures at the highest temperature and Pr, where imidazole is bound most weakly, at the lowest. Consistent with these facts is the observation that the Yb compound also gives the longest latency period when mixed with epoxy resin.
Polymeric amines and their copper(II) complexes: Catalysts for the hydrolysis of organophosphate esters
Authors: Bao Y. T. , Pitt C. G.
Published: April 2003

Catalysis of the solvolysis of organophosphorus esters by polymers of aliphatic amines, imidazole, pyridine, 2,2′‐bipyridine, and their copper(II) complexes was studied using diisopropyl fluorophosphate (DEP) as a model substrate. The polymeric catalysts were synthesized either by (1) derivation of available polymers, including polyethylenimine, polyvinyl amine, polyvinyl alcohol, polystyrene, and poly‐4‐vinylpyridine or (2) by polymerization of functionalized monomers such as 4(5)‐vinylimidazole and 4‐vinyl‐4′‐methyl‐2,2′‐bipyridine. Polymer hydrophilicity was controlled by partial quaternization of amine groups with different alkyl halides. The greatest catalytic activity was exhibited by copper(II) complexes of polymers containing the 2,2′‐bipyridine group. At pH 7.6 and 3.7 × 10−3M, the most active of these catalysts reduced the half‐life of DFP from 800 to 9 min. The rate was largely independent of the pH in the range 6.5–8.5 but was limited by the aqueous solubility of the catalyst. Heterogeneous catalysis by some polymers was observed but was less effective. A Lineweaver‐Burk plot of V0−1 versus [DFP]−1 for a soluble polymeric 2,2′‐bipyridine‐copper(II) catalyst was linear. There was no correlation between catalysis of solvolysis of DFP and the carboxylic ester, p‐nitrophenyl acetate.
Polymer drying. III. Comparison of molecular desorption from poly(styrene‐co‐divinylbenzene) in the gel‐state and in the glass‐state
Authors: Errede L. A.
Published: April 2003

The results observed in 44 time‐studies that monitored evaporation from liquid‐saturated poly(Sty‐co‐DVB) particles enmeshed in poly(tetrafluoroethylene) microfibers under conditions that precluded decrease in area of the microporous composite film sample verified that after the enmeshed particles undergo transition from the gel‐state to the glass‐state, the number of residual adsorbed molecules per phenyl group of polymer is given by a linear combination of n < 7 exponential decay functions, the first order rate constants of which are related to one another by the equation: log ki = log k0 − mi, where m is characteristic of the polymer, and k0 is characteristic of the sorbed liquid such that k1 is about 105 times faster than k6. The results also show that k1 of the set of nki for desorption from poly(Sty‐co‐DVB) in the glass‐state is equal to kgel, the first‐order rate constant for desorption of the test‐liquid from that polymer in the gel‐state. These results are interpreted to mean that i, the identification number of the ith population, reflects the number of phenyl groups in the “host” polymer with which the “guest” volatile molecule is associated simultaneously as discussed in the text.
Polymer drying. IV. A molecular interpretation of polymer drying
Authors: Errede L. A.
Published: April 2003

Further consideration of data already collected, in many time‐studies that monitored gravimetrically evaporations of acetone, toluene, and chloroform from the corresponding liquid‐saturated poly(styrene‐co‐divinylbenzene) samples, show that αt, the residual number of sorbed molecules per phenyl group at a given level of desorption, is a linear function of αs, the number of adsorbed molecules per accessible phenyl group in the polymer at thermodynamic equilibrium with excess test‐liquid. Such linear relationships were noted at successive break‐points in the kinetics of desorption (from gel‐saturation to virtual dryness) that signaled sequentially (a) incipient elimination of adsorbed molecules from polymer in the rubbery state, (b) incipient transition from the rubbery state to the glassy state, (c) completion of this transition, and (d) successive depletions of five of the six populations of residual adsorbed molecules that were trapped in six different molecular environments by rigidification of the system during the transition. These results support the viewpoint that αs is a parameter that reflects how well the molecular structure of the sorbed molecule can be accommodated by that of the monomer unit of the polymer.
Efficient, “one‐pot” synthesis of silylene–acetylene and disilylene–acetylene preceramic polymers from trichloroethylene
Authors: Ijadi‐Maghsoodi Sina , Pang Yi , Barton Thomas J.
Published: April 2003

An extremely efficient process has been developed for the synthesis of linear silylene‐acetylene and disilylene‐acetylene polymers. Trichloroethylene is quantitatively converted by n‐butyllithium to dilithioacetylene. Quenching with dialkyl‐or diaryldichlorosilanes affords high yields of the polymers, \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm SiR}_{\rm 2} \hbox{---} {\rm C} \equiv {\rm C\rlap{--} ]}_n ,{\rm and }\rlap{--} [{\rm SiMe}_{\rm 2} {\rm SiMe}_{\rm 2} - {\rm C} \equiv {\rm C\rlap{--} ]}_n $\end{document} if ClMe2SiSiMe2Cl is employed. Molecular weights are much higher with this route than when acetylene is used as the dilithio‐ or dimagnesium acetylide precursor. Some of these polymers can be pulled into continuous fibers, and all can be cast into coherent films and thermally converted into silicon carbide.
Radical copolymerization of 2‐acryloyl thioxanthone with methyl methacrylate
Authors: Catalina F. , Peinado C. , Madruga E. L. , Sastre R. , Mateo J. L. , Allen N. S.
Published: April 2003

A novel monomer, 2‐acryloyl thioxanthone (TXA), was prepared by reaction of 2‐hydroxy thioxanthone with acryloyl chloride. Copolymerization of TXA with methyl methacrylate (MMA) in DMF at 80°C was studied in order to evaluate relative reactivities of these monomers. Values of 1.36 and 0.5 were found for the respective reactivity ratios of MMA and TXA, respectively. The resonance stabilization and polar properties were determined and discussed in terms of spectroscopic data.
Modeling of unseeded emulsion copolymerization of styrene and methyl methacrylate
Authors: Forcada J. , Asúa J. M.
Published: April 2003

A mathematical model for the unseeded emulsion copolymerization of styrene and methyl methacrylate has been developed. This model, which includes a new rate coefficient for radical desorption, was used to analyze the effect of the styrene/methyl methacrylate molar ratio in the initial charge on the number of particles, overall conversion and copolymer composition. It was found that the number of particles increased with the methyl methacrylate content and that a drift of the copolymer composition resulted during the polymerization of styrene/methyl methacrylate molar ratios other than 50/50. Good agreement between experimental results and model predictions was achieved.
The polymerization of 3‐chloro‐1‐propyne and 3‐bromo‐1‐propyne with Mocl5 and WCL6 based initiators and the structure of the resulting polymers
Authors: Kunzler J. , Percec V.
Published: April 2003

The WCl6 and MoCl5 initiated polymerizations of 3‐chloro‐1‐propyne and 3‐bromo‐1‐propyne were performed in both halogenated and aliphatic non‐nucleophilic and in aromatic nucleophilic solvents. The structure of the obtained polymers suggested that the polymerization reaction occurs in two steps. In both nucleophilic and non‐nucleophilic solvents, the first step consists of the metathesis polymerization of 3‐chloro(bromo)‐1‐propyne followed by electrophilic cis–trans isomerization leading to polymers containing trans‐cisoidal allyl chloride or bromide structural units. When the polymerization is performed in non‐nucleophilic solvents, in the second step an intramolecular electrophilic addition followed by elimination takes place. The resulting polymers contain a highly conjugated cyclopentadiene ladder structure. When the polymerization is performed in nucleophilic aromatic solvents, the intramolecular electrophilic addition competes with the electrophilic substitution of the solvent resulting in polymers containing high concentrations of arylpropenyl structural units. Subsequently, depending on the nucleophilicity of the polymerization solvent, the polymer structure contains structural units based on cyclopentadiene and/or arylpropenyl groups.