bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterogeneous chloroacetylation of chitosan powder in the presence of sodium bicarbonate
Authors: Jenkins David W. , Hudson Samuel M. 
Published: August 2002

AbstractBecause of the importance of the chloroacetyl group to carbohydrate synthesis, the objective of this work is to disclose a method that has been found useful for the heterogeneous chloroacetylation of chitosan powder in which sodium bicarbonate is used as the base for the neutralization of the acid byproduct. A series of reactions were conducted to determine the more optimal conditions under which to perform acylation. The three varied aspects of the reaction were the acylating reagent (chloroacetyl chloride and chloroacetic anhydride), the solvent (methylene chloride and N,N‐dimethylformamide), and the temperature (0 or 44 °C). According to Fourier transform infrared (FTIR), the chitosan powder being refluxed in methylene chloride in the presence of chloroacetic anhydride constituted the best conditions. By incorporating these conditions and increasing the amount of the base, we obtained a chloroacetylated chitosan powder that, characterized by FTIR, solid‐state cross‐polarity/magic‐angle spinning 13C NMR, and elemental analysis, had degrees of N‐ and O‐chloroacetylation of 0.32 and 0.15, respectively. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4174–4181, 2001
Poly(ethylene terephthalate) copolymers containing 5‐nitroisophthalic units. III. Methanolytic degradation
Authors: Kint Darwin P. R. , de Ilarduya Antxon Martínez , Bou Jordi J. , Muñoz‐Guerra Sebastián 
Published: August 2002

AbstractThe methanolysis of poly(ethylene terephthalate) (PET) copolymers containing 5‐nitroisophthalic units was investigated. Random copolyesters containing 10 and 30 mol % of such units were prepared via a two‐step melt copolycondensation of bis(2‐hydroxyethyl) terephthalate (BHET) and bis(2‐hydroxyethyl) 5‐nitroisophthalate (BHENI) in the presence of tetrabutyl titanate as a catalyst. First, the susceptibility of these two comonomers toward methanolysis was evaluated, and their reaction rates were estimated with high‐performance liquid chromatography. BHENI appeared to be much more reactive than both BHET and bis(2‐hydroxyethyl) isophthalate. The methanolysis of PET and the copolyesters was carried out at 100 °C, and the degradation process was followed by changes in the weight and viscosity, gel permeation chromatography, differential scanning calorimetry, and 1H and 13C NMR spectroscopy. The copolyesters degraded faster than PET, and the rate of degradation increased with the content of nitrated units. The products resulting from methanolysis were concluded to be dimethyl terephthalate, dimethyl 5‐nitroisophthalate, ethylene glycol, and small, soluble oligomers. For both PET and the copolyesters, an increase in crystallinity was observed during the degradation process, indicating that methanolysis preferentially occurred in the amorphous phase. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 76–87, 2002
Synthesis of a novel one‐pot approach of hyperbranched polyurethanes and their properties
Authors: Hong Ling , Cui Yanjun , Wang Xinling , Tang Xiaozhen 
Published: August 2002

AbstractA new method for the synthesis of hyperbranched polymers involving the use of ABx macromonomers containing linear units have been investigated. Two types of novel hyperbranched polyurethanes have been synthesized by a one‐pot approach. The structures of monomers and polymers were characterized by elemental analysis, 1H NMR, 13C NMR, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. The hyperbranched polymers have been proven to be extremely soluble in a wide range of solvents. Polymer electrolytes were prepared with hyperbranched polymer, linear polymer as the host, and lithium perchlorate (LiClO4) as the ion source. Analysis of the isotherm conductivity dependence of the ion concentration indicated that these hyperbranched polymers could function as a “solvent” for the lithium salt. The conductivity increased with the increasing concentration of hyperbranched polymers in the host polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 344–350, 2002
Synthesis and structure‐property relationship of new donor–acceptor‐type conjugated monomers and polymers on the basis of thiophene and benzothiadiazole
Authors: Jayakannan M. , van Hal Paul A. , Janssen René A. J. 
Published: August 2002

AbstractWe have synthesized three new donor–acceptor‐type monomers to achieve soluble and processable low‐band gap polymers, 4,7‐bis(4‐octyl‐2‐thienyl)‐2,1,3‐benzothiadiazole (B4TB), 4,7‐bis(3‐octyl‐2‐thienyl)‐2,1,3‐benzothiadiazole (B3TB), and 4‐(3‐octyl‐2‐thienyl)‐7‐(4‐octyl‐2‐thienyl)‐2,1,3‐benzothiadiazole (B34TB), by the Suzuki coupling reaction. Using B4TB and B3TB, two soluble high molecular weight regioregular head‐to‐head and tail‐to‐tail polymers poly[4,7‐bis(4‐octyl‐2‐thienyl)‐2,1,3‐ benzothiadiazole] (PB4TB) and poly[4,7‐bis(3‐octyl‐2‐thienyl)‐2,1,3‐benzothiadiazole] (PB3TB) were prepared via iron(III) chloride‐mediated oxidative polymerization. The structures of the polymers were confirmed by 1H and 13C NMR, and the molecular weights were determined by size exclusion chromatography. The optical properties (absorbance and fluorescence) of the monomers and polymers were studied and compared with unsubstituted analogues. The monomers and polymers bearing octyl substituents on the thiophene rings pointing away from the benzothiadiazole units (B4TB and PB4TB) possess a more planar structure, and their optical spectra appear redshifted as compared with those having the octyl chain nearer to the benzothiadiazole (B3TB and PB3TB). The optical band gaps of PB3BT (Eg = 2.01 eV) and PB4BT (Eg = 1.96 eV), however, are at much higher energy levels than that of the unsubstituted electrochemically polymerized PBTB material (Eg = 1.1–1.2 eV) as a result of steric effects of the octyl chains. The electrochemical properties of the monomers and polymers were examined using cyclic voltammetry and reflect the effect of alkyl substitution. B4TB and PB4TB were oxidized at a lower potential than B3TB and PB3TB, whereas their reduction potentials were less negative. The electrochemical band gap calculated from the onset of the reduction and oxidation process agreed with the optical band gap calculated from the absorption edges. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 251–261, 2002
Free‐radical crosslinking copolymerization of 2,2′‐azobis[N‐(2‐propenyl)‐2‐methylpropionamide] with vinyl benzoate resulting in polymeric azo initiators
Authors: Matsumoto Akira , Ichiryu Yoshikatsu , Aota Hiroyuki , Shiraki Kazuo , Iwata Tsutomu 
Published: August 2002

Abstract2,2′‐Azobis[N‐(2‐propenyl)‐2‐methylpropionamide] (APMPA) with two carbon–carbon double bonds and an azo group was copolymerized with vinyl benzoate (VBz) at 60 °C, resulting in azo groups containing VBz/APMPA prepolymers and crosslinked polymers as soluble and insoluble polymeric azo initiators, respectively. The polymerization characteristics of APMPA as a novel diallyl monomer were clarified with the rate and degree of polymerization and the monomer reactivity ratios. The gelation behaviors in VBz/APMPA crosslinking copolymerizations were examined in detail with a comparison of the actual gel point and the theoretical gel point calculated according to Stockmayer's equation with the tentative assumption of equal reactivity for both vinyl groups belonging to VBz and APMPA. The effectiveness of the resulting branched or crosslinked poly(VBz‐co‐APMPA)s as soluble or insoluble polymeric azo initiators, respectively, at providing graft polymers through the cleavage of azo groups at an elevated temperature was examined by the polymerization of allyl benzoate at 120 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 317–325, 2002
Main‐chain viologen polymers with organic counterions exhibiting thermotropic liquid‐crystalline and fluorescent properties*
Authors: Bhowmik Pradip K. , Han Haesook , Cebe James J. , Burchett Ronald A. , Sarker Ananda M. 
Published: August 2002

AbstractA series of viologen polymers with bromide, tosylate, and triflimide as counterions were prepared by either the Menshutkin reaction or metathesis reaction in a common organic solvent. Their polyelectrolyte behavior in methanol was determined by solution viscosity measurements, and their chemical structures were determined by Fourier transform infrared and Fourier transform NMR spectroscopy. They were characterized for their thermotropic liquid‐crystalline properties with a number of experimental techniques. Each of the viologen polymers with organic counterions had a low melting transition or fusion temperature above which it formed either a high‐order smectic phase or a low‐order smectic phase. Each of them also exhibited a smectic‐to‐isotropic transition. The ranges of the liquid‐crystalline phase were 80–88 °C for viologen polymers with tosylate as a counterion and 120–146 °C for viologen polymers with triflimide as a counterion. They had excellent thermal stability. The ranges of thermal stability were 288–329 °C for viologen polymers with tosylate as a counterion and 343–350 °C for viologen polymers with triflimide as a counterion. The fluorescence property for all of the viologen polymers in either aqueous or methanol solution was also included in this study. For example, the viologen polymer containing the 4,4′‐bipyridinium and p‐xylyl units along the backbone of the polymer chain with triflimide as a counterion had an absorption spectrum (λmax = 265 nm), an excitation spectrum (λex values = 357, 443, and 454 with monitoring at 533 nm), and an emission spectrum (λem = 536 nm with excitation at 430 and 450 nm) in methanol. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 659–674, 2002; DOI 10.1002/pola.10134
Bulk free‐radical photopolymerizations of 1‐vinyl‐2‐pyrrolidinone and its derivatives
Authors: White L. A. , Hoyle C. E. , Jonsson S. , Mathias L. J. 
Published: August 2002

AbstractAn investigation of the free‐radical bulk photopolymerization of 1‐vinyl‐2‐pyrrolidinone (NVP) with an NVP‐based crosslinker, 1,6‐(bis‐3‐vinyl‐2‐pyrrolidinonyl)hexane (BNVP), and an NVP‐based comonomer, 3‐hexyl‐1‐vinyl‐2‐pyrrolidinone (VHP), was carried out. The enthalpies of polymerization were determined for NVP and VHP to be 30.8 and 35.7 kJ/mol, respectively. The rates of polymerization were determined for NVP/VHP and NVP/BNVP systems at various temperatures. These photopolymerization studies revealed that the overall rates of polymerization of these 3‐alkylated‐2‐pyrrolidinone derivatives increased with substitution onto the pyrrolidinone ring. A series of pyrrolidinone‐based additives in bulk NVP were used in model photopolymerizations of NVP for the evaluation of plasticizer effects. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 694–706, 2002; DOI 10.1002/pola.10142
Synthesis and optical properties of soluble polyethers containing oligophenyl in the main chain and p‐styrylbenzene side groups
Authors: Spiliopoulos Ioakim K. , Mikroyannidis John A. 
Published: August 2002

AbstractNew polyethers containing alternating conjugated segments of p‐terphenyl or p‐quinquephenyl with p‐styrylbenzene side groups and aliphatic spacers were synthesized with pyrylium salts. They had moderate molecular weights, were amorphous, and dissolved in tetrahydrofuran, chloroform, and other common organic solvents. The glass‐transition temperatures were 68–82 and 110–153 °C for the polymers that carried p‐terphenyl and p‐quinquephenyl moieties, respectively. The absorption spectra showed a peak around 325 nm, and the band gaps were 3.27–3.34 eV, which were calculated from the onset absorption in solution. The photoluminescence maxima were at 393–398 nm in solution and 422–449 nm in thin films, indicating that the polymers were violet‐blue‐emitting materials. The photoluminescence quantum yields in solution were up to 0.25. The polymers displayed both in concentrated solutions and in the solid state intramolecular or intermolecular interactions. The polarity of the solvent influenced the shape of the photoluminescence curve. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 682–693, 2002; DOI 10.1002/pola.10151
Emulsion copolymerization of vinylidene chloride and methyl methacrylate. I. Effects of operating variables on the kinetic behavior
Authors: Nomura M. , Sakai H. , Kihara Y. , Fujita K. 
Published: August 2002

AbstractThe effects of operating variables on the kinetic behavior of the emulsion copolymerization of vinylidene chloride (VDC) and methyl methacrylate (MMA) were examined at 50 °C with sodium lauryl sulfate as an emulsifier and potassium persulfate as an initiator, respectively. The number of polymer particles produced increased in proportion to the 1.0 power of the initial emulsifier concentration and to the 0.3 power of the initial initiator concentration and decreased with an increasing content of MMA in the initial monomer charge. The rate of copolymerization was proportional to the 0.4 power of the initial emulsifier concentration and to the 0.5 power of the initial initiator concentration and increased with an increasing content of MMA in the initial monomer charge. The molecular weight of copolymer produced decreased drastically with an increasing content of VDC in the initial monomer charge. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1275–1284, 2002
Simultaneous construction of the polymer backbone and side chains by three‐component polycondensation: The synthesis of polyurethanes with allyl side chains from dialdehydes, alkylene N,N′‐bis(trimethylsilyl) carbamates, and allyltrimethylsilane
Authors: Niimi Lui , Serita Ken‐Ichi , Hiraoka Shuichi , Yokozawa Tsutomu 
Published: August 2002

AbstractPolyurethanes with allyl side chains were synthesized by the simultaneous acid‐catalyzed reaction of dialdehydes (1), alkylene N,N′‐bis(trimethylsilyl) carbamates (4), and allyltrimethylsilane (5). When 5 was added to a mixture of 1, 4, and the catalyst, a low molecular weight polymer was formed, as well as a large amount of an insoluble gel. However, when a mixture of 1, 4, and 5 was added to the catalyst, the formation of gel was depressed, and the desired polyurethanes, consisting of 1, 4, and 5 in a molar ratio of 1/1/2, were obtained in good yields. This polyurethane synthesis is unusual in that it concurrently constructs both the polymer backbone and the functional side chains from three starting compounds. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1236–1242, 2002
Derivatization of propene/methyloctadiene copolymers: A flexible approach to side‐chain‐functionalized polypropenes
Authors: Song Fuquan , Pappalardo Daniela , Johnson Anthony F. , Rieger Bernhard , Bochmann Manfred 
Published: August 2002

AbstractThe copolymerization of propene with 7‐methyl‐1,6‐octadiene (MOD) catalyzed by Cp*TiMe3/B(C6F5)3 (A) and rac‐C2H4(Ind)2ZrCl2/methylaluminoxane (B) in toluene under 1 bar propene gave copolymers with unsaturated side chains. Under these conditions, catalyst A produced copolymers with an atactic backbone structure of type 1, with 3.5–19.6 mol % MOD incorporation and weight‐average molecular weight = 0.7–2.7 × 105. Using catalyst B, copolymers 2 with 0.4–3.8 mol % MOD incorporation were prepared. The comonomer incorporation was a linear function of the feed ratio. The titanium catalyst A had a significantly higher affinity for MOD than the sterically more hindered zirconocene B. Postpolymerization modification of the side‐chain CC bond allowed the facile introduction of a wide variety of functional groups. Epoxidation and especially ozonolysis of the CC bond, to give CHO and COOH functionalized copolymers, proved to be very facile routes to functionalized polypropenes. According to monitoring by NMR, most of these transformations proceed in an essentially quantitative conversion. As an example of potential applications of such polymers, polypropenes with covalently attached dyes were prepared that are suitable for blending. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1484–1497, 2002
Synthesis of a model cyclic triblock terpolymer of styrene, isoprene, and methyl methacrylate
Authors: Pantazis Dimitris , Schulz Donald N. , Hadjichristidis Nikos 
Published: August 2002

AbstractThe synthesis of a model cyclic triblock terpolymer [cyclic(S‐b‐I‐b‐MMA] of styrene (S), isoprene (I), and methyl methacrylate (MMA) was achieved by the end‐to‐end intramolecular amidation reaction of the corresponding linear α,ω‐amino acid precursor [S‐b‐I‐b‐MMA] under high‐dilution conditions. The linear precursor was synthesized by the sequential anionic polymerization of S, I, and MMA with 2,2,5,5‐tetramethyl‐1‐(3‐lithiopropyl)‐1‐aza‐2,5‐disilacyclopentane as an initiator and amine generator and 4‐bromo‐1,1,1‐trimethoxybutane as a terminator and carboxylic acid generator. The separation of the unreacted linear polymer from the cyclic terpolymer was facilitated by the transformation of the unreacted species into high molecular weight polymers by the evaporation of the reaction solvent and the continuation of the reaction under high‐concentration conditions. The intermediate materials and the final cyclic terpolymer, characterized by size exclusion chromatography, vapor pressure osmometry, thin‐layer chromatography, IR and NMR spectroscopy, exhibited high molecular weight and compositional homogeneity. Dilute‐solution viscosity measurements were used as an additional proof of the cyclic structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1476–1483, 2002
Syntheses and polymerizations of novel chiral poly(acrylamide) macromonomers and their chiral recognition abilities
Authors: Oishi Tsutomu , Lee Yong‐Kyung , Nakagawa Akira , Onimura Kenjiro , Tsutsumi Hiromori 
Published: August 2002

AbstractChiral poly(acrylamide) macromonomers (PMB‐1, PMB‐2, PPAE‐1, and PPAE‐2) were synthesized from 2‐methacryloyloxyethyl isocyanate and prepolymers, that is, poly[(S)‐methylbenzyl acrylamide] or poly(L‐phenylalanine ethylester acrylamide with a terminal carboxylic acid or hydroxy group. Radical homopolymerizations of poly(acrylamide) macromonomers were carried out under several conditions to obtain the corresponding optically active polymers. A strong temperature dependence on the specific optical rotation was observed for poly(PPAE‐2) in comparison with that for the corresponding prepolymer. This might have resulted from a change in the conformation caused by hydrogen bonds between polymer‐graft branches in the polymacromonomer. Radical copolymerizations of poly(acrylamide) macromonomers with styrene and methyl methacrylate were performed with azobisisobutyronitrile in tetrahydrofuran at 60 °C. Chiroptical properties of the copolymers were slightly influenced by comonomer units. Chiral stationary phases were prepared by the radical polymerization of poly(acrylamide) macromonomers in the presence of silica gel containing vinyl groups on the surface. Some racemic compounds such as menthol and mandelic acid were resolved on the chiral stationary phases for high‐performance liquid chromatography. The conformation based on hydrogen bonds between polymer‐graft branches in the polymacromonomers may play an important role in chiral discrimination. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1726–1741, 2002
Monomer reactivity ratios of the 2‐(3‐mesityl‐3‐methylcyclobutyl)‐2‐hydroxyethyl methacrylate and styrene system from 1H NMR
Authors: Erol Ibrahim , Soykan Cengiz , Erol Misir Ahmedzade 
Published: August 2002

Abstract2‐(3‐Mesityl‐3‐methylcyclobutyl)‐2‐hydroxyethyl methacrylate (MCHEMA) was prepared from the reaction of methacrylic acid with the oxirane compound obtained from the chlorhydrin formed in the cyclization of 1‐chloro‐2,3‐epoxy‐5‐methyl‐5‐hexene. Copolymers of MCHEMA and styrene were prepared in 1,4‐dioxane solution at 60 °C using 2,2′‐azobisisobutyronitrile as the initiator. They were characterized by IR, 1H NMR, and 13C NMR spectra. Their compositions were determined by the 1H NMR technique. The monomer reactivity ratios were determined by the Fineman–Ross, Kelen, Tüdös, and Yezrielev–Brokhina–Roskin method. Thermogravimetric analysis of the copolymers was carried out under a nitrogen atmosphere. The glass‐transition temperature of the copolymers as determined by differential scanning calorimetry agreed with the Flory–Fox relationship. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1756–1763, 2002
Synthesis and properties of new hydroxyl‐pendant aromatic polyimides derived from trimethylsilylated 4,4′‐diamino‐3,3′‐dihydroxybiphenyl and aromatic tetracarboxylic dianhydrides
Authors: Imai Yoshio , Itoya Kazuo , Kanamaru Masami , Kakimoto Masa‐Aki 
Published: August 2002

AbstractNew phenolic hydroxyl‐pendant aromatic polyimides were synthesized with the N‐silylated diamine method in two steps: the ring‐opening polyaddition of tetrakis(trimethylsilyl)‐substituted 4,4′‐diamino‐3,3′‐dihydroxybiphenyl to various aromatic tetracarboxylic dianhydrides, giving trimethylsiloxy‐pendant poly(amic acid) trimethylsilyl esters, and thermal imidization. The hydroxyl‐bearing polyimides were amorphous but insoluble in organic solvents. They had glass‐transition temperatures greater than 370 °C and temperatures of 10% weight loss greater than 415 °C in nitrogen. The hydroxyl‐pendant polypyromellitimide film had a high tensile strength and a high modulus of 310 MPa and 10 GPa, respectively. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1790–1795, 2002
Synthesis and hydrophobic association of poly(N,N‐dimethylacrylamide) end‐functionalized with perfluorocarbon and hydrocarbon groups
Authors: Xie David , Tomczak Sandra , Hogen‐Esch Thieo E. 
Published: August 2002

AbstractPolydimethylacrylamides (PDMAs) end‐functionalized with hydrophobic groups were synthesized by the reaction of cesium salts of one‐ or two‐ended living PDMA anion with octadecanoyl and perfluorooctanoyl chlorides and with α‐phenylacrylate monomers containing an octadecyl group attached via oligooxyethylene spacers to the acrylate functionality. Size exclusion chromatography or NMR studies indicated that the end functionalizations were nearly quantitative. Reduced viscosity measurements were consistent with predominantly dimeric association of the perfluorooctanoyl‐end‐functionalized PDMAs. The association of the two‐ended, perfluorooctanoyl‐ and octadecanoyl‐functionalized polymers was more extensive and consistent with pairwise association. Furthermore, the presence of oligoethylene oxide spacers between the octadecyl and α‐phenylacrylate groups greatly enhanced the hydrophobic association of bis(octadecyl)‐end‐functionalized PDMA. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1403–1418, 2001