bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and radical polymerization of ethyl α‐acetoacetoxymethylacrylate
Authors: Sato Tsuneyuki , Morita Naoki , Tanaka Hitoshi , Ota Tadatoshi 
Published: April 2003

AbstractEthyl α‐acetoacetoxymethylacrylate (1) was prepared by reaction of diketene and ethyl α‐hydroxymethylacrylate which was obtained from the reaction of triethyl phosphonoacetate and an aqueous solution of formaldehyde. 1 contains 27% of the enol tautomer. The polymerization of 1 in benzene initiated with dimethyl 2,2′‐azoisobutyrate (2) was investigated kinetically. The overall activation energy of polymerization was determined to be 84,8 kJ/mol. The polymerization rate (Rp) at 50°C is expressed by Rp = k[2]0,5 [1]1,1. From an electron spin resonance study, the polymerization system was revealed to involve persistent propagating poly(1) radicals. The rate constants of propagation and termination were estimated to be kp = 300 and kt = 1,0 · 106 1 · mol− · s− at 60°C, respectively, using the polymer radical concentration and assuming stationary state conditions. Copolymerization of 1 (M1) and styrene (M2) was examined at 50°C, and the following copolymerization parameters were obtained; r1 = 0,28, r2 = 0,22, Q1 = 1,2, and e1 = +0,87.
Sedimentation equilibrium in a density gradient and characterization of the molecular weight distribution of poly(methyl methacrylate)
Authors: Härzschel Reinhard , Meyerhoff Günter 
Published: April 2003

AbstractThe determination of average molecular weights and the characterization of molecular weight distributions by the ratio of the weight‐ to number‐average molecular weights M̄w/M̄n from sedimentation equilibrium in the ultracentrifuge are described. The essential measurement of the density profile of the mixed solvent is conducted according to Munk (Macromolecules 15, 500 (1982)). Special evaluation of the polymer band in the equilibrium allowed to deduce from the observed concentration profile M̄w and M̄n of a series of poly(methyl methacrylate) samples and thus to characterize the molecular weight distribution of the samples.
Untersuchungen zum selbstinitiierungs‐mechanismus der thiol/En‐polymerisation
Authors: Klemm Elisabeth , St. Sensfuß  
Published: April 2003

AbstractThe UV absorption spectrum of an equimolar mixture of 3,6‐dioxaoctane‐1,8‐dithiol (4) and ethylene glycol divinyl ether (1) shows a broad charge‐transfer absorption in the range of 380–420 nm. The absorption band is destroyed in the course of two hours, and the absorption spectrum is identical with that of the poly(thioether) (5). The number‐average molar mass M̄n of such a reaction product amounts to 4 300 g · mol−1 after 24 h. Addition of chloranil or 1,4‐diazabicyclo[2.2.2]octane (DABCO) leads to an effective inhibition of the spontaneous polymerization. DSC investigations confirmed the experimental results.
Polymeric protecting groups, 4. Amino‐protection with tert‐butoxycarbonyl‐analogous comblike methacrylic polymers by aminolysis of activated carbonates
Authors: Gormanns Marcus , Rehse Henning , Ritter Helmut 
Published: April 2003

AbstractThe synthesis of highly amino‐sensitive activated carbonates based on tert‐butoxycarbonyl(BOC)‐modified monomers was performed by reaction of phthalimido chloroformate and phenyl chloroformate with the free OH groups of N‐(2‐hydroxy‐2‐methylpropyl)methacrylamide (1), N‐(3‐hydroxy‐3‐methylbutyl)methacrylamide (2) and N‐(2‐hydroxy‐2‐methylpropyl)‐6‐methacrylamidohexanamide (6), respectively. The monomeric carbonates were radically homo‐ and copolymerized with methyl methacrylate (MMA). The kinetics of aminolysis of these polymers with hexanamide was followed by UV and NMR spectroscopy. Differences between phthalimide‐ and phenyl‐containing systems, neighbouring group effects, influence of different comonomers and spacer groups on the reactivity of the activated carbonates are discussed.
Study on the NdCl3‐supported Ziegler‐Natta catalyst for olefin polymerization
Authors: Xiao Shijing , Wang Hai , Cai Shimian 
Published: April 2003

AbstractThe catalyst NdCl3/EtOH/TiCl4 (NSC) was prepared using NdCl3 as carrier. The composition of the NSC was analyzed by IR, XPS, GC and titration. This catalyst and MgCl2/EtOH/TiCl4 catalyst (MSC) were employed for the polymerization of ethylene and propene. The titanium component in NSC exists basically as Ti(OEt)Cl3 but both as TiCl4 and Ti(OEt)Cl3 in MSC. NSC combined with organoaluminium compounds polymerizes ethylene with fairly high productivity. Both the activity and the concentration of active centres C* in ethylene polymerization with NSC‐AlEt3 catalyst system decrease with increasing temperature, while the propagation rate constant kp increases. The difference in the kinetic behavior for polymerization of ethylene between the NSC‐AlEt3 and the MSC‐AlEt3 catalyst system would arise mainly from the different stability and reactivity of the titanium active center. The activity for polymerization of propene by using NSC in comparison to MSC is very low.
Solvent effects on free‐radical polymerization, 2. IR and NMR spectroscopic analysis of monomer mixtures of methyl methacrylate and N‐vinyl‐2‐pyrrolidone in bulk and in model solvents
Authors: Czerwinski Wojciech Krzysztof 
Published: April 2003

AbstractBinary systems of methyl methacrylate (MMA)/N‐vinyl‐2‐pyrrolidone (NVP) and MMA/N‐methyl‐2‐pyrrolidone (NMP) with NMP as saturated model of NVP and of NVP/methyl isobutyrate (MiB) with MiB as saturated model of MMA were investigated by means of IR and NMR spectroscopy. Investigations were carried out at room temperature or at 60°C in CHCl3 (IR) or CDCl3 and C6H12/C6D12 (NMR). It can be concluded from IR and NMR spectra that the polarity of MMA increases in the presence of NVP and the polarity of NVP decreases in the presence of MMA. Equilibrium constants K of complex formation were determined to: K = 0,169 ± 0,037 L · mol−1 for MMA/NVP at 30°C, 0,112 ± 0,024 L · mol−1 for NVP/MiB at 60°C and 0,125 ± 0,030 L · mol−1 for MMA/NMP at 60°C.
Enzymes in polymer chemistry, 5. Radical polymerization of different 11‐methacryloylamino‐undecanoic acid esters and oligoesters esterfied by lipases
Authors: Pavel Konstantin , Ritter Helmut 
Published: April 2003

Abstract11‐Methacryloylaminoundecanoic acid (1) was esterified with the monoalcohols isobutyl alcohol, cyclohexanol, DL‐menthol, cholesterol, testosterone and an excess of 12‐hydroxylauric acid in the presence of lipase as catalyst. The kinetics of the esterification reactions were followed by 1H NMR spectroscopy and the results were correlated with sterical effects. The monomers were polymerized radically. The monomeric 12‐hydroxylauric acid oligoester 11 as well as its homopolymer 12 were characterized by DSC and viscosity measurements.
Role of bulky α‐substituent in free‐radical polymerization and copolymerization of methyl α‐(alkoxymethyl)acrylates
Authors: Yamada Bunichiro , Satake Masayuki , Otsu Takayuki 
Published: April 2003

AbstractMethyl α‐(alkoxymethyl)acrylates were prepared from methyl α‐(bromomethyl)acrylate in 80–90% yield. The monomers homopolymerize fast to yield low‐molecular‐weight polymers. The monomers bearing a linear alkoxymethyl group except for the ethoxymethyl group are characterized by a relatively low ceiling temperature. The rate constants for propagation kp and termination kt of methyl α‐(butoxymethyl)acrylate were evaluated to be kp = 298 dm3 · mol−1 · s−1 and kt = 8 · 106 dm3 · mol−1 · s−1 at 60°C, respectively. The α‐(alkoxymethyl)acrylates are more reactive than methyl methacrylate toward polystyrene radical, except for the α‐(dodecyloxymethyl)acrylate which is slightly less reactive, indicating that an increase in the reactivity by the electron‐withdrawing character of the alkoxy group prevails over the steric hindrance against addition of the polymer radical, except for the large dodecyloxymethyl group.
Side‐chain liquid‐crystalline polymers containing a siloxane spacer, 1. Synthesis of side‐chain liquid‐crystalline polymers containing siloxane bond in the spacer unit
Authors: Nagase Yu , Takamura Yuriko 
Published: April 2003

AbstractSide‐chain liquid‐crystalline polymers containing siloxane bond in the spacer units were prepared. For the synthesis of the desired monomers, novel silanol compounds carrying a mesogenic group were prepared as the intermediates. The polymers were obtained by ordinary free‐radical polymerization. As the mesogenic groups, p‐ or p′‐cyano‐substituted biphenyl group, phenyl and biphenylyl benzoates were chosen, and the structural effects on the thermal properties were investigated. Introduction of a disiloxane group in the side chain resulted in a decrease of Tg which was more marked for longer siloxane units. Furthermore, only when a terphenylene‐type mesogen was introduced, a stable smectic mesophase was observed with wide range of phase stability.
Synthesis and cytotoxic activity of doxorubicin bound to poly(α‐malic acid) via ester or amide bonds
Authors: Ohya Yuichi , Hirai Keiichi , Ouchi Tatsuro 
Published: April 2003

AbstractPoly(α‐malic acid) is of interest for the application as a biodegradable and bioadsorbable drug carrier, which has pendent reactive carboxylic acid groups. In order to provide a biodegradable macromolecular prodrug of doxorubicin (adriamycin, ADR), reducing the side‐effects of ADR and exhibiting effective antitumor activity, ADR residues were covalently attched to poly(α‐malic acid) via ester or amide bonds to give poly(α‐malic acid)/ester/ADR conjugate 1 or poly(α‐malic acid)/amide/ADR conjugate 2, respectively. The release rate of ADR from the poly(α‐malic acid)/ester/ADR conjugate 1 was faster than that from the poly(α‐malic acid)/amide/ADR conjugate 2 in buffer solution (pH 7,4) at 37°C. While the cytotoxic activity of poly(α‐malic acid)/ester/ADR conjugate 1 is as strong as that of free ADR against p388D1 lymphocytic leukemia cells in vitro, the cytotoxic activity of poly(α‐malic acid)/amide/ADR conjugate 2 is much lower.
Spacer length and molecular weight variation on ferroelectric liquid crystalline polymers
Authors: Kühnpast Kurt , Springer Jürgen , Davidson Patrick , Scherowsky Günter 
Published: April 2003

AbstractThe influence of the spacer length (n = 2, 6, 8 and 11 methylene groups) on the polymorphism and the ferroelectric properties of liquid crystalline side‐group polyacrylates with a 4‐[(R)‐4‐(1‐methylheptyloxy)‐4′‐biphenylyloxycarbonyl]phenoxy moiety was studied. Various molecular weights were obtained from the polymers with n = 8 and n = 11. All the polymers show SmC* phases. A SmC* phase polymorphism was even found for most of the polymers. In some of these SmC* phases, no ferroelectric properties could be measured. The structural differences between the SmC* phases and their influence on the appearance of the ferroelectric properties are not yet clear. However, a SmC̃* phase was put in evidence, revealing a tendency to a chevron‐like ordering which may explain the complex SmC* polymorphism of these systems.
Polyamides from 2,2′‐p‐phenylenebis(Δ2‐5‐oxazolone)s and N,N′‐bistrimethylsilylated diamines. Synthesis of polyamides containing dipeptide links in the main chains
Authors: Katsarava Ramaz , Kharadze Darejan , Kirmelashvili Larisa , Medzmariashvili Nino , Goguadze Tsisana , Tsitlanadze George 
Published: April 2003

AbstractA new polyamidation reaction between N,N′‐bistrimethylsilylated diamines and 2,2′‐p‐phenylenebisazalactones in N,N‐dimethylacetamide was investigated. By the interaction of bisazalactones with Nα, Nε‐bistrimethylsilylated L‐lysin alkyl ester, polyamides were obtained containing dipeptide links in the main chain. It was shown that these can be transformed into water‐soluble polyacids upon saponification of ester side groups.
Anionic equilibrium polymerization of α‐methylstyrene initiated by butyllithium/dimethoxyethane and glyme‐1
Authors: Liang Liang , Shengkang Ying 
Published: April 2003

AbstractThe kinetics and mechanism of anionic equilibrium polymerization of α‐methaylstyrene in cyclohexane with butyllithium (BuLi) as initiator and dimethoxyethane (DME) and glyme‐1 (bis(2‐methoxyethyl)) ether; (1G) as polar additives were investigated. The apparent constant of propagation kap and of depropagation kad were evaluated over a wide concentration range of DME (or 1G). The kinetic equations of the equilibrium polymerization as mole ratios of [DME]/[BuLi] < 1,66, [DME]/[BuLi] > 33,3 and 1,66 < [DME]/[BuLi] < 33,3 were established. The mathematic equations of the equilibrium monomer concentration [M]e deduced from the kinetic measurements, at the above mentioned ratios [DME]/[BuLi], were used to control the polymerization process. The rate constants of different active species and the equilibrium constants between active species were calculated by the curve fitting method for the DME system. The fact that free ions exist in the polymerization system when the concentration of 1G was about 40 vol.‐% was proved by conductance measurements. Finally, the reaction features of the anionic polymerization of α‐methylstyrene with various polar additives are compared.
Kinetic and ESR studies on radical polymerization. Radical polymerization behavior of N‐octadecylmaleimide in benzene
Authors: Sato Tsuneyuki , Masaki Koji , Seno Makiko , Tanaka Hitoshi 
Published: April 2003

AbstractThe polymerization of N‐octadecylmaleimide (1) initiated with azodiisobutyronitrile (2) was investigated kinetically in benzene. The overall activation energy of the polymerization was calculated to be 94,2 kJ·mol−1. The polymerization rate (Rp) at 50°C is expressed by the equation, Rp = k[2]0,6[1]1,7. The homogeneous polymerization system involves ESR‐detectable propagating polymer radicals. Using Rp and the polymer radical concentration determined by ESR, the rate constants of propagation (kp) and termination (kt) were evaluated at 50°C. kp (33 L · mol−1 · s−1 on the average) is substantially independent of the monomer concentration. On the other hand, kt (0,3 · 104 – 1,0 · 104 L · mol−1 · s−1) is fairly dependent on the monomer concentration, which is ascribable to a high dependence of kt on the chain length of rigid poly(1). This is the predominant factor for the high order with respect to the monomer concentration in the rate equation. In the copolymerization of 1 (M1) and St (M2) with 2 in benzene at 50°C, the following copolymerization parameters were obtained: r1 = 0,11, r2 = 0,09, Q1 = 2,1, and e1 = +1,4.
Synthesis and non‐linear optical characteristics of crosslinked and linear epoxy polymers with pendant tolane chromophores
Authors: Zentel Rudolf , Jungbauer Dietmar , Twieg Robert J. , Yoon Do Y. , Willson C. Grant 
Published: April 2003

AbstractLinear and crosslinked epoxy polymers containing high concentrations (ca. 86 wt.‐%) of pendant 4‐(4‐nitrophenylethynyl)aniline [4‐amino‐4′‐nitrotolane] chromophores were synthesized. They exhibit a smectic phase in the bulk once heated above the glass transition temperature (ca. 70°C). The appearance of the highly scattering smectic phase could be avoided by starting the crosslinking process of thin polymer films in the presence of solvent. Application of corona poling during crosslinking resulted in a highly polar polymer, exhibiting a very large birefringence of ca. 0,17 at 633 nm. Moreover, the birefringence remained stable during annealing at 80–90°C for ca. 30 days. The electro‐optic coefficient, determined from the Pockels‐effect, was roughly 8 pm/V for r113 at 633 nm.
Thermochromic properties of polythiophenes: structural aspects
Authors: Roux Claudine , Bergeron Jean‐Yves , Leclerc Mario 
Published: April 2003

AbstractTemperature‐dependent optical absorption measurements have revealed important thermochromic effects in poly(3‐dodecylthiophene) and poly(3‐octyloxy‐4‐methylthiophene) between 25 and 150°C which are related to a planar to non‐planar transition of the main polymer chain. This conformational transition is caused by an increase of the repulsive intrachain steric interactions upon heating, which then force the thiophene backbone to adopt a non‐planar conformation. On the other hand, as observed with poly(3‐octyloxythiophene), if the side chains do not lead to large steric interactions, the polymer can maintain a highly conjugated structure even at high temperatures while, if the steric interactions are too strong (e.g. poly(3,3′‐dihexyl‐2,2′‐bithiophene)), no co‐planar conformation can be adopted.
Oxidation of poly(vinyl alcohol) with an oxoammonium salt
Authors: Yoshida Eri , Yamaguchi Masao , Takata Toshikazu , Endo Takeshi 
Published: April 2003

AbstractOxidation of poly(vinyl alcohol) (PVA) with 1‐oxo‐4‐methoxy‐2,2,6,6‐tetramethylpiperidinium chloride (oxoammonium salt, 1) prepared by a one‐electron oxidation of the corresponding nitroxyl radical (2) was carried out. PVA with a degree of polymerization (DP) of 300 and a degree of saponification (DS) of 88 mol‐% was oxidized with 1 in the presence of magnesium perchlorate in N‐methyl‐2‐pyrrolidone (NMP) to obtain a polymer containing 66 mol‐% of ketone units. The oxidation was found to be dependent on solvent and additive and further, independent of DP but dependent on DS of PVA. In the case of PVA with extremely low (10 mol‐%) or high (98,5 mol‐%) DS, no or little oxidation took place. The highest ketone content was obtained in a polymer with a DS of 88 mol‐%. Moreover, the ketone content of the oxidized PVA could be controlled by the amount of 1.
Conformational behaviour of linear and crosslinked poly(4‐but‐3‐en‐1‐ynyl‐1‐methylpiperidin‐4‐ol) in solution
Authors: Kudaibergenov Sarkyt E. , Saltybaeva Saule S. , Bekturov Esen A. , Nurkeeva Z. S. , Sigitov V. B. , Shaikhutdinov E. M. , Ermagambetov M. F. 
Published: April 2003

AbstractThe conformational transition expanded coil to compact globule for linear and crosslinked poly(4‐but‐3‐en‐1‐ynyl‐1‐methylpiperidin‐4‐ol), poly{1‐[2‐(4‐hydroxy‐1‐methyl‐4‐piperidyl)ethynyl]ethylene}, (1) in aqueous and aqueous‐salt solutions was investigated. The free energy of the conformational transition for linear 1. n HCl was calculated. It was shown that in aqueous solution 1 is characterized by a lower critical solution temperature (LCST). The collapse of crosslinked 1 on changing the ionization state (aqueous salt solution) and temperature was observed and is similar to a phase transition.
The role of water in the electrodeposition and doping of polythiophene and two of its derivatives
Authors: Beck Fritz , Barsch Ulrich 
Published: April 2003

AbstractThe galvanostatic electropolymerization of thiophene (1), 3‐methylthiophene (2) and 2,2′‐bithiophene (3) in acetonitrile, containing 0,002 to 20 mol/L water, was studied in detail. The current efficiency γ for the polymer film formation decreased rapidly for 1, but much slower for 2 and 3 with increasing water concentration c. For c = 0,1 mol/L, γ was found to be 10, 82 and 95% for 1–3. It was possible to describe the experimental γ vs. c plots quantitatively by a model where the electrogenerated radical cations (rc) of the thiophene (derivative) are consumed by two competing second‐order follow up reactions, the nucleophilic attack of the rc by water (i) and the rate‐determining dimerization of two rc's (ii). Their rates are given by: (i) v1 = k1 crc c and (ii) v2 = k2 c2rc. The side reaction (i) leads to soluble products, while reaction (ii) contributes to the polymer film growth. The ratio k1/k2 was found to be 3 · 10−7, 2 · 10−8 and 4 · 10−9 for 1, 2 and 3, respectively, and this shows that the electropolymerization of 2,2′‐bithiophene is by a factor of about 100 less sensitive toward the present water than thiophene. The steady state concentration crc is in the order of 10−9 mol/L in all three cases. The relative insensitivity of doping/undoping cycles with respect to the presence of water is discussed in terms of a lessened reactivity of the polarons and a low solubility of water in the heteroaromatic polymer.
Crystal structure and mesophase morphology of MBPE polyethers containing odd‐number methylene spacers
Authors: Chen Jianhua , Zhang Anqiu , Yandrasites Michael A. , Cheng Stephen Z. D. , Percec Virgil 
Published: April 2003

AbstractA series of polyethers was synthesized from 4‐[2‐(4‐hydroxyphenyl)ethyl]‐3‐methylphenol and α, ω‐dibromoalkenes, MBPE‐n. The polymers with odd‐numbered methylene spacers show a monotropic mesophase behavior during cooling from the isotropic melt before crystallization. The crystal structures of MBPE (n = odd) polyethers have been investigated through wide angle X‐ray diffraction fiber patterns. Two crystallographic periods along the c‐axis are found, one of which corresponds to the length of methylene spacers, and the other is close to an integral number times the length of the repeating unit. Polarized light microscopy observations of the uniaxially oriented samples obtained through mechanical shear show a banded texture, which is a typical morphology found in liquid crystal polymers. Transmission electron microscopy experiments provide morphological evidence to identify that this mesophase is a nematic liquid crystal state based on the disclination defect patterns defined by Frank. A relationship between splay elastic constant k11 and bend elastic constant k33 is discussed through lamellar decoration of disclination defects.
Chain branching accompanying the synthesis of polystyrene with pendent 2‐hydroxyethyl groups: An investigation of the reaction of phenyllithium with oxirane in the presence of N,N,N′,N′‐tetramethylethylenediamine
Authors: Beinert Gerard J. , Zilliox Jean G. , Herz Jean E. 
Published: April 2003

AbstractThe reaction of plurilithiated polystyrenes with oxirane in the presence of N,N,N′,N′‐tetramethylethylenediamine yields not only the expected polymers fitted with pendent 2‐hydroxyethyl groups but also couples and branched products. The side reactions are rather important when using a stoichiometric amount of oxirane with regard to the lithiated sites but can be partly suppressed in presence of an excess of oxirane. A possible reaction pathway was established on the basis of a model reaction: under similar conditions the reaction of phenyllithium with oxirane leads to 2‐phenylethanol and to a few percents of 3,4‐diphenyl‐1‐butanol and 2‐(3,4‐diphenylbutoxy)ethanol. However, the presence of these two diphenyl derivatives among the reaction products may explain the existence of coupled and branched species in the functionalized polystyrene.
Two‐component copolymer networks. Synthesis of polystyrene/poly(dimethylsiloxane) copolymer network and its swelling behavior in mixed solvents
Authors: Shiomi Tomoo , Okada Koji , Tezuka Yasuyuki , Kazama Hideki , Imai Kiyokazu 
Published: April 2003

AbstractA two‐component copolymer network comprising polystyrene (PS) and poly(dimethylsiloxane) (PDMS) as copolymer components was prepared by cross‐linking PS with telechelic PDMS. In the first stage of the cross‐linking reaction, PS having 5–6 mol ‐% of sodium acrylate units along the main chain was ionically coupled with bifunctional PDMS having 1‐methylpyrrolidinium salt groups on both chain ends, and then the ionic coupling was converted to covalent bonds at 100°C by ring‐opening of the 1‐methylpyrrolidinium salt upon nucleophilic attack of the carboxylate counter anion. The resulting PS/PDMS networks were subjected to investigation of swelling behavior in three kinds of mixed solvents which were chosen so as to contrast with one another in respect of solubility of the component polymers. Three different types of swelling behavior were obtained which regard to the solvent composition dependence.