bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical synthesis of poly(1,4‐phenylene) films
Authors: Fauvarque Jean‐Francois , Petit Michel‐Alain , Digua Abdelouafi , Froyer Gérard
Published: April 2003

Homogeneous films of poly(1,4‐phenylene) (PPP) can be deposited on various materials by electro‐reduction of 4,4′‐dibromobiphenyl in presence of a nickel complex catalyst. UV and IR spectra indicate that the polymer has a regular structure (exclusively 1,4‐phenylene units) and an unusual average molecular weight. The nascent PPP films are obtained in their neutral from and can be either reduced or oxidized.
Combined liquid‐crystalline polymers with chiral phases, 1 2‐octanol as chiral end of the mesogens
Authors: Bualek Sauvarop , Zentel Rudolf
Published: April 2003

Combined liquid‐crystalline polymers containing azobenzene and azoxybenzene as the mesogenic groups and 2‐octanol as the chiral end‐group were synthesized and characterized. These polymers exhibit cholesteric, smectic A, and chiral smectic C* phases with monolayer and doublelayer structures. The polymers with azoxy groups do not crystallize upon cooling. Therefore, some of the liquid‐crystalline phases can be frozen in in the glassy state.
Copolymerisation von acetylen mit acetylenderivaten, 1. Copolymerisation von acetylen mit phenylacetylen
Authors: Kanischka Gerd , Höcker Hartwig
Published: April 2003

Copolymers were obtained from acetylene and phenylacetylene by coordinative polymerization with MoCl5 as a catalyst in toluene as solvent. The copolymers were characterized by spectroscopic methods as well as by means of differential scanning calorimetry and gel permeation chromatography. The fraction of phenylvinylene units in the copolymers was determined by means of UV spectroscopy as well as the conjugation length of planar double bonds which increases with increasing fraction of vinylene units. The fraction of vinylene units in the copolymers was determined by IR spectroscopy. DSC measurements indicate the transformation temperature for isomerization, cyclization, aromatization and chain scission to decrease with increasing fraction of vinylene units. At high contents of vinylene units in the copolymers a trans‐cisoide configuration is realised, while for pure polyphenylacetylene and copolymers with a low vinylene fraction the cis‐transoide configuration is favoured. With increasing content of vinylene units the solubility of the copolymers decreases, while oxidizability and degradation reactions increase. These reactions are favoured at higher temperatures and upon light irradiation. The oligomeric fractions of the copolymers indicate the presence of biphenyl o,‐ m‐ and p‐terphenyl, 1,1′:2′,1″:4′,1 ‴‐ and 1,1′:3′,1″:5′,1 ‴‐quaterphenyl.
Initiation of polymerization with substituted ethanes, 11 Chromatographic separation of methyl methacrylate oligomers and NMR analysis of the diastereoisomers
Authors: Bledzki Andrzej , Balard Henri , Braun Dietrich
Published: April 2003

The free radical oligomerization of methyl methacrylate using different tetraphenylethane initiators [1,2‐diphenoxy‐1,1,2,2‐tetraphenylethane (4), tetraphenylsuccinonitrile (5), and 1,1,2,2‐tetraphenyl‐1,2‐bis(trimethylsiloxy)ethane (6)] gives telechelics 1 – 3 with end groups originating from the initiator. These telechelics were characterized by gel permeation, thin layer, and high performance chromatography. By adsorption chromatography, the separation does not only proceed in accordance with the molecular weight of the oligomers, but also with their tacticity as well. The free radical oligomerization is a process in which syndiotactic structures are favoured above isotactic ones.
Preparation and properties of polymerizable ferroelectric liquid‐crystalline acrylate and methacrylate derivatives
Authors: Shiraishi Kohei , Sugiyama Kazuo
Published: April 2003

(+)‐2‐Methylbutyl 4‐[4‐(11‐acryloyloxyundecyloxy)benzylideneamino]cinnamate (3a) and (+)‐2‐methylbutyl 4‐[4‐(11‐methacryloyloxyundecyloxy)benzylideneamino]cinnamate (3b) were synthesized. 3a possesses a chiral smectic C (S*c) phase. From electro‐optical measurements of 3a, the rise time of the surface director (τsr) and the rise time of the bulk director (τbr) are found to be 0,32 ms and 110 ms, respectively.
Synthesis and properties of macromonomers carrying phosphatidylcholine analogous and azobenzene moieties
Authors: Sugiyama Kazuo , Shiraishi Kohei
Published: April 2003

Macromonomers 6a, b, carrying phosphatidylcholine analogous and azobenzene moieties as a photoresponsive pigment, were prepared from the reaction of 2‐oxo‐1,3,2λ5‐dioxaphospholane derivatives 2 and poly[2‐dimethylaminoethyl methacrylate] macromonomer 5. 6b shows a nematic phase. The mesogenic group is connected with the chromophore via a flexible spacer group. Phase transition temperatures were determined by measurement of the rapid change in conductivity of the solutions of the amphiphiles with the temperature. From the result of photoreversible cis‐trans isomerization it can be concluded that 6b can possibly be used as a photoresponsive material of a membrane.
Poly(ether/ester)s based on poly(tetramethylene terephthalate) and poly(ethylene glycol), 4. Modification with 2‐butyne‐1,4‐diol
Authors: Gogeva Tanya , Fakirov Stoyko
Published: April 2003

A series of poly(ether/ester)s derived from dimethyl terephthalate, 1,4‐butanediol, 2‐butyne‐1,4‐diol (2‐BD‐1,4) and α‐hydro‐ω‐hydroxypoly(oxyethylene) (molecular weight 1000) is synthesized. The mole ratio of the starting components is selected to result in copolymers with constant hard : soft segment weight ratio (59:41). The amount of 2‐BD‐1,4 is varied from 0 to 20 wt.‐% referred to the total amount of the short‐chain diols used. The incorporation of 2‐BD‐1,4 in the macrochains is proved by 1H NMR measurements. A small increase of the oxygen index is found with increasing the amount of 2‐BD‐1,4. It is established that the poly(ether/ester) containing 10 wt.‐% of 2‐BD‐1,4 behaves as known poly(ether/ester)s. Data from differential scanning calorimetry suggest a three‐phase structure, two amorphous and one crystalline one. Small‐angle X‐ray studies of the annealed samples reveal a strong tendency to phase separation with increasing the annealing temperature. The latter is in agreement with density measurements.
Synthesis and radical polymerization of ethyl α‐acetoacetoxymethylacrylate
Authors: Sato Tsuneyuki , Morita Naoki , Tanaka Hitoshi , Ota Tadatoshi
Published: April 2003

Ethyl 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

The 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

The 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

The 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

The 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

Binary 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

11‐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

Methyl 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

Side‐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

Poly(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

The 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

A 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

The 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

The 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

Linear 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

Temperature‐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

Oxidation 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

The 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

The 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

A 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

The 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

A 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.
Thermodynamics of cycloalkenes, of their bulk polymerization in the presence of matathesis catalysts and of polyalkenes
Authors: Lebedev Boris , Smirnova Natal'ya
Published: April 2003

Principal regularities of the thermodynamics in ring‐opening bulk polymerization of cycloalkenes (cyclononene, cyclodecene, cycloundecene, cyclododecene, cyclotridecene, cyclotetradecene and cyclopentadecene) as established from precise calorimetric studies are considered. For all monomers and polymers studied the temperature dependence of the heat capacity was investigated in the range of 5 K to 400 K, and the temperatures and enthalpies of physical transitions were determined. The enthalpies of combustion of a number of monomers and polymers were measured, and for some monomers direct calorimetric measurements of enthalpies of polymerization were made. From the data obtained the thermodynamic functions H0(T) − H0(0), S0(T), G0(T) − H0(0) were calculated for all compounds under study in the range from 0 to 400 K and for some monomers and polymers the enthalpies of formation at T = 298,15 K and pressure p = 101,325 kPa. For monomers in the glassy state zero entropies Sgl0(0) were estimated and the difference in zero enthalpies of polymers in the glassy and the crystalline state Hgl0(0) − Hcr0(0) was determined. Enthalpies, entropies and Gibbs functions of polymerization were calculated between 0 and 400 K at standard pressure.
Synthesis and cationic ring‐opening polymerization of 2‐methylene‐7‐oxabicyclo[2.2.1]heptane
Authors: Bai Ruke , Li Shihua , Zou Yinfang , Pan Caiyuan , Uryu Toshiyuki
Published: April 2003

A new unsaturated bicyclic ether, 2‐methylene‐7‐oxabicyclo[2.2.1]heptane (4) was synthesized by successive Diels‐Alder addition of furan to acrylonitrile, hydrogenation of cyano compound 5, and Hofmann degradation of the quaternary ammonium hydrate 7 derived from the amine 6. Cationic polymerization of the monomer 4 was carried out in CH2Cl2 using BF3 · OEt2, PF5, SbCl5 and SnCl4 as catalysts in the temperature range of −20 to −25°C. White or slightly yellow powdery polymers of low molecular weight were obtained with PF5 and BF3 · OEt2 as catalysts, while no polymer was obtained with SbCl5 and SnCl4 as initiators. The IR, 1H and 13C NMR spectra of the polymers indicated that they consist of three kinds of repeating units, that is, two unsaturated units caused by ring‐opening polymerization and one addition unit. Using proton NMR data of the polymers, the distribution of repeating units was calculated. A polymerization mechanism is proposed. The thermal stability of the obtained polymers is discussed.
Synthesis, solution properties, and glass transition temperatures of polymethacrylates with alicyclylmethyl side groups
Authors: Pateropoulou Despina , Siakali‐Kioulafa Ekaterini , Hadjichristidis Nikos , Nan Shouyan , Mays Jimmy W.
Published: April 2003

The synthesis, solution properties, and glass transition temperatures of polymethacrylates having alicyclic rings connected to the ester linkage via methylene spacers are reported. The rings cover the range in size from cyclobutyl to cycloundecyl. An attempt was also made to prepare and study poly(cyclopropylmethyl methacrylate), but free radical solution polymerization led to gels. Solution and thermal properties of these polymers are compared to those previously reported for polymethacrylates with both alicyclyl and n‐alkyl substituents. The introduction of the methylene spacer between the ester linkage and the ring results, for small rings, in diminished characteristic ratios relative to those obtained for the alicyclyl materials. Chain flexibilities of poly(alicyclylmethyl methacrylates) are instead found to be identical to those of poly(n‐alkyl methacrylates) having the same number of carbons. The glass transition temperatures of the poly(alicyclylmethyl methacrylates) are generally intermediate to those observed for alicyclyl and n‐alkyl methacrylates, but are closer to the former.
Critical epitaxial layers of different kinds of polyethylene on highly oriented isotactic poly(propylene) substrates
Authors: Yan Shouke , Lin Jian , Yang Decai , Petermann Jürgen
Published: April 2003

Epitaxial crystallization of high‐density polyethylene (HDPE), linear low‐density polyethylene (LLDPE) and low‐density polyethylene (LDPE) in the epitaxial system with highly oriented isotactic poly(propylene) (iPP) has been investigated by electron microscopy. The results obtained by bright field electron microscopy and electron diffraction confirmed that all of the three kinds of PE (HDPE, LLDPE and LDPE) have the ability of epitaxy on iPP surfaces. There exists a critical thickness of the PE layer in which the PE can grow epitaxially on iPP substrates. When the PE/iPP layered films are heat‐treated at a temperature above the melting temperature (Tm) of PE and below Tm of iPP for 10 min and then quenched to room temperature, the critical layer thickness of epitaxial HDPE, LLDPE and LDPE is about 250, 120 and 30 nm, respectively. For PE further apart from the interface, the epitaxial orientation becomes disturbed due to simultaneous spherulitic nucleation or lamellar twisting of the epitaxially grown lamellae.
p‐Phenylene‐2,2′‐bis(3‐aminopropenenitrile) and its polymerization with terephthaloyl dichloride
Authors: Sikkema Doetze J. , Reichwein John
Published: April 2003

With the aim of preparing a new rigid rod type polymer, we worked out a synthesis of the title compound: 1,4‐bis(chloromethyl)benzene was reacted with KCN, and the product was formylated with ethyl formate; exchange of enol by enamine function by treatment with ammonium acetate completes the synthesis. Polymerization of this only mildly nucleophilic monomer with terephthaloyl dichloride proceeded rather slowly and only moderate chain length polymer proved accessible. The cyclization envisioned could be shown to proceed as desired in a model compound from the title compound with benzoyl chloride. Upon putative cyclization, the polymer remained soluble in sulfuric acid.
Détermination des masses et des distributions moléculaires d'un poly(aryléthercétone‐co‐sulfone) semi‐cristallin (HTX) à l'aide d'une méthode de dérivatisation chimique, 2. Chromatographie d'exclusion stérique du HTX sulfoné
Authors: Daoust Daniel , Godard Pierre , Devaux Jacquex
Published: April 2003

HTX, a poly(aryletherketone‐co‐sulfone), is characterized by size exclusion chromatography (SEC) at room temperature. As HTX is not soluble in any solvent compatible with the SEC instrumentation, a derivatization procedure is applied in order to prepare a modified copolymer with improved solubility properties. This derivatization consists in a sulfonation by concentrated sulfuric acid. The derivative polymer is soluble in N‐methyl‐2‐pyrrolidone (NMP), a classical SEC solvent. Sulfonated HTX (HTXS) is a polyelectrolyte. Consequently, a salt is added to NMP to perform reliable viscometric and SEC analyses. The SEC method is standardized with the establishment of the universal calibration with poly(methyl methacrylate) standards and the determination of the Mark‐Houwink‐Sakurada relationship of HTXS in NMP‐salt at 25°C. Finally, the reliability of the derivatization procedure and of the SEC method is confirmed by comparison with molecular masses from NMR.
Electrooptically active polymers. Non‐linear optical polymers prepared from maleic anhydride copolymers by polymer analogous reactions
Authors: Ahlheim Markus , Lehr Friedrich
Published: April 2003

The synthesis of new high‐molecular‐weight non‐linear optical (NLO) polymers, prepared by polymer analogous reaction of maleic anhydride copolymers with aminoalkyl functionalized azo dyes is described. The thermal behavior of the resulting copolymers is discussed in terms of molar dye concentration, polymer main‐chain flexibility and spacer length on the glass transition temperature.
Polymerization of 1,2‐epoxypropane and 1,2‐epoxycyclohexane by diethylzinc‐polyhydric phenol and/or phenol or 1‐phenoxy‐2‐propanol as catalysts
Authors: Kuran Witold , Listoś Tomasz
Published: April 2003

1,2‐Epoxypropane and 1,2‐epoxycyclohexane were polymerized in the presence of catalysts derived from reactions of diethylzinc with a polyhydric phenol (4‐tert‐butylcatechol, pyrogallol) and/or phenol or 1‐phenoxy‐2‐propanol in 1,4‐dioxane solution, varying the polymerization temperature and time. The polymers formed in these polymerizations were analysed by means of 1H NMR, 13C NMR and UV spectroscopy in terms of the polymer chain microstructure and chain end‐groups. The poly(propylene oxide) (PPO) obtained appeared to be a high‐molecular‐weight polymer with prevailing isotactic diads (mole fraction in the range of 0,65–0,72). It was found to consist of a predominant amorphous (atactic) fraction and a crystalline (isotactic) fraction. An enhancement of both the crystallinity and the average molecular weight of PPO was observed with an elongation of the duration of the polymerization. Therefore, it was concluded that the catalyst enantioselectivity increases with progressing polymerization. The poly(cyclohexene oxide) (PCHO) obtained appeared to be a polymer with prevailing syndiotactic diads (mole fraction in the range of ca. 0,58–0,80) and threo‐enchainement of monomeric units. This was explained in terms of inversion of the configuration at the carbon atom of the epoxide ring upon cleavage. A possible mechanism for the epoxide polymerization by the coordination catalysts studied is presented.
Telechelic polystyrene obtained by degradation of polyurethane‐polystyrene block copolymers
Authors: Kinoshita Hiroshi , Tanaka Nobuo , Araki Takeo , Ooka Masataka
Published: April 2003

Polystyrene with one or two terminal hydroxyl groups was obtained in a high yield (88–90%) from polyurethane‐polystyrene block copolymers (PU‐PS). The block copolymers were prepared by radical polymerization of styrene with a polyurethane‐type macroazo initiator, and then the urethane bonds were degraded with 2‐aminoethanol. The purity of the hydroxylated polystyrene thus obtained, which consists predominantly of the dihydroxy‐telechelic component, was much higher (ca. 90%) than that of polystyrene obtained by conventional radical polymerization using the corresponding low‐molecular‐weight azo initiator 2,2′‐azobis(2‐cyanopropanol) (ca. 80% mono‐ and dihydroxylated polystyrene). Formation of a predominantly telechelic HO—PS—OH was confirmed from the results of the polyaddition reaction of the hydroxylated polystyrene with a diisocyanate.
Viscometric study of extremely dilute solutions of two polymers with different molecular weights
Authors: Papanagopoulos Dimitrios , Dondos Anastasios
Published: April 2003

The intrinsic viscosity of a polymer A (referred to as guest polymer) in a solvent containing a second polymer B (referred to as host polymer) at constant concentration was found to be lower than the intrinsic viscosity of the same polymer in the pure solvent. This decrease becomes more important as the molecular weight of the host polymer becomes smaller. When the intrinsic viscosity of a low‐molecular‐weight guest polymer is measured in the presence of a high‐molecular‐weight host polymer, no such decrease is observed and the decrease of the dimensions of a guest polymer in the presence of a host polymer of comparable molecular weight, is insignificant. A parameter bAB is introduced characterizing the hydrodynamic interactions between the two polymers in the region of extremely dilute solutions. The values of bAB strongly depend on the difference in the segment densities between the two polymers.
Spinning and characterization of fibers from poly(2,6‐dichloro‐p‐phenyleneterephthalamide): a study of constitutional isomerism and solid‐state arrangements by comparison between simulation and experiment
Authors: Glomm Bernhard H. , Rutledge Gregory C. , Küuchenmeister Frank , Neuenschwander Peter , Suter Ulrich W.
Published: April 2003

Fibers of three constitutionally isomeric rigid‐rod polymers, produced by polycondensation of 2,6‐dichloro‐p‐phenylenediamine and terephthaloyl dichloride, were spun from nematic solutions and characterized by wide‐angle X‐ray diffraction (WAXD) measurements and mechanical tests. A post‐spin heat treatment was employed to improve the low degrees of orientation and crystallinity that the untreated fibers showed. The dominating crystal structure of constitutionally ordered head‐to‐head/tail‐to‐tail fibers seems to be very similar to “Modification II” of the fibers from poly(p‐phenyleneterephthalamide) (PPTA), but the fibers do not suffer a comparable structural transformation upon heat treatment. Influences of the constitutional regularity in the chains on the crystal structure, structural order and mechanical properties of the fibers could be observed. Both the observed crystal structure and the experimentally determined mechanical properties agree well with the results of detailed atomistic modeling predictions.
Ionic conduction of cross‐linkable oligo(oxyethylene)‐branched poly(phosphazene)
Authors: Tada Yuji , Sato Moriyuki , Takeno Noboru , Kameshima Takashi , Nakacho Yoshifumi , Shigehara Kiyotaka
Published: April 2003

A new cross‐linkable polyphosphazene [AEP7] in which allyl groups were introduced at the ends of the etheric side chains of the polymer was prepared. The LiClO4/AEP7 hybrids showed relatively high ionic conductivity of 7,9·10−5 S·cm−1 at 25°C with 6 wt.‐% of LiClO4. The ionic conductivity of the hybrids remained unchanged before and after cross‐linking by UV‐irradiation. The dimensional stability or the mechanical strength of the hybrids was improved upon cross‐linking. Additionally, the cross‐linked AEP7(29)/propylene carbonate (PC)(60)/LiClO4(11) (wt.‐%) hybrids, in which PC was used as a plasticizer, showed an ionic conductivity as high as 3,1·10−3 S·cm−1 at 25°C.
Particle growth in butadiene emulsion polymerization, 1. The use of Fremy salt as aqueous radical scavenger
Authors: Verdurmen Edwin M. , Geurts John M. , German Anton L.
Published: April 2003

The kinetics of the seeded emulsion polymerization of butadiene in combination with variable Fremy salt (potassium nitrosodisulfonate) concentrations was investigated in order to monitor non‐steady state kinetics necessary for obtaining information on entry and exit of radicals from latex particles. Fremy salt is used because it is an entirely water‐soluble stable radical that in principle can scavenge water‐soluble radicals produced by a water‐soluble initiator like peroxodisulfate, but allegedly will not interfere with radicals within latex particles. Adequate buffering of the pH is a prerequisite for stable Fremy salt concentrations in time. Emulsion polymerizations in the presence of Fremy salt showed that not all radicals in the aqueous phase of a swollen polybutadiene latex are scavenged. The use of Fremy salt to monitor non‐steady state kinetics in the seeded emulsion polymerization of butadiene in the presence of tertiary dodecyl mercaptan yields no satisfying results. The use of Fremy salt seems to be restricted to systems where the rate of polymerization is strongly influenced by variation in initiator concentration, i.e. the styrene system or the butadiene system in the absence of tertiary dodecyl mercaptan.
Particle growth in butadiene emulsion polymerization, 4. The promoting effect of mercaptans
Authors: Verdurmen Edwin M. , Verstegen John M. , German Anton L.
Published: April 2003

The observation that butadiene emulsion polymerizations in the presence of fatty acid emulsifiers need minimal amounts of tertiary or n‐dodecanethiols to polymerize at a reasonable rate is often referred to as the promoting effect of mercaptans and is evaluated in this paper. Experimental evidence is presented which shows that fatty acid emulsifiers can actively reduce the average number of radicals per particle. In this paper it will be shown that three components are necessary for retardation of the rate of polymerization in the absence of dodecanethiol to occur: (1) Only diene monomer polymerizations show retardation. (2) Only peroxodisulfate‐initiated polymerizations show retardation. (3) Retardation of the rate of polymerization only occurs in the presence of fatty acid emulsifiers. These three components are combined for the first time in a reaction scheme which is an extension of a reaction scheme proposed by Kolthoff in 1951. Experimental evidence justifies the suggestion that reaction between a fatty acid radical and butadiene play an important role in the promoting effect.
Kinetic study on thermal polymerization and cross‐linking of pre‐irradiated 1,4‐butanediol diacrylate
Authors: Selli Elena , Bellobono Ignazio Renato , Oliva Cesare
Published: April 2003

The thermal polymerization and cross‐linking of 1,4‐butanediol diacrylate taking place after irradiation was followed kinetically in the temperature range from 60 to 140°C. Low conversions were reached by polychromatic pre‐irradiation in the absence of any photoinitiating species. The disappearance of double bonds follows first‐order kinetics, up to degree of conversion 0,4 < x < 0,5, and then proceeds up to high x values, according to a multiple relaxation phenomenon, characterized by the same mean relaxation lifetime as first‐order kinetics. Activation parameters also were calculated. The present results on the decay of double bonds are discussed in the framework of the classical polymerization mechanism and in connection with previous kinetical data on the decay of radicals trapped in the same pre‐irradiated monomer, obtained by electron paramagnetic resonance (EPR) measurements. Propagation and termination processes depend in the same way on the mobility of the vitrified polymerized network, both being diffusion‐controlled.
Block copolymers by sequential group transfer polymerization: poly(methyl methacrylate)‐block‐poly(2‐ethylhexyl acrylate) and poly(methyl methacrylate)‐block‐poly(tert‐butyl acrylate)
Authors: Masař Bohumil , Vlček Petr
Published: April 2003

Poly(methyl methacrylate)‐block‐poly(2‐ethylhexyl acrylate) (PMMA‐block‐PEHA) and poly(methyl methacrylate)‐block‐poly(tert‐butyl acrylate) with a methacrylate/acrylate unit ratio of 1:1 and 1:3, 16000 < Mn < 44000 and 1,9 < Mw/Mn < 2,5, were prepared by sequential group transfer polymerization using (1‐methoxy‐2‐methyl‐1‐propenyloxy)trimethylsilane as initiator and tetrabutylammonium fluoride monohydrate as a catalyst in tetrahydrofuran at −30°C, PMMA being the first block. The increase in Mn during the successive addition of monomers is linearly dependent on the (co)polymer yield and size‐exclusion chromatography (SEC) curves are shifted towards higher molecular weights in comparison with PMMA macroinitiators. The block structure of the copolymers was also proven by extraction experiments. The presence of homopolymers in the copolymers was not detected. When the former copolymer is prepared in a reverse way (PEHA segment being the first), the MMA polymerization ceases at ≈ 43–45% conversion.