bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermotropic polyesters with flexible spacers in the main chain and oligo(oxyethylene) substituents
Authors: Bhowmik Pradip K. , Garay Paul O. , Lenz Robert W.
Published: April 2003

An expanded series of alkoxy‐and oligo(oxyethylene)‐substituted thermotropic polyesters with flexible decamethylene spacers in the main chain, which have higher molecular weights than those described in an earlier report, were prepared and characterized. All of the polymers in the series are soluble in common organic solvents, and have low melting temperatures (Tm) and isotropization transition temperatures (Ti). The members of the series with oligo(oxyethylene) substituents form both smectic and nematic phases.
Radical and spontaneous thermal polymerizations of some captodative‐substituted acrylates
Authors: Tanaka Hitoshi , Kameshima Takashi , Sasai Kensuke , Sato Tsuneyuki , Ota Tadatoshi
Published: April 2003

The polymerization of some captodative‐substituted acrylates was examined in the presence and absence of 2,2′‐azoisobutyronitrile (AIBN) at 60 °C. Methyl acrylates, substituted by acetoxy, methoxy and ethylsulfenyl groups in α‐position, and tert‐butyl α‐methoxyacrylate homopolymerized with and without this initiator. The rate of AIBN‐initiated homopolymerization of methyl α‐acetoxyacrylate was as high as that of methyl methacrylate in spite of the captodative‐substituted monomer, and these acrylates also gave polymers spontaneously in remarkably high yield even under conditions under which styrene and methyl methacrylate are not polymerized. Copolymers of these monomers with styrene also were obtained in the presence and in the absence of AIBN. The mechanism of the initiation of the spontaneous thermal polymerization is discussed on the basis of ESR spectra, reaction intermediates and radical inhibition experiments.
Physicochemical behaviour of the sodium salt of carboxymethylcellulose in dye, salt and surfactant environments
Authors: Gupta Syamasri , Moulik Satya Priya , Das Akhil Ranjan
Published: April 2003

The interactions of the polyelectrolyte carboxymethylcellulose (sodium salt) with salts, dyes and surfactants have been studied by viscometry, conductometry, spectrophotometry and membrane potential measurements. The compact conformation of the polyelectrolyte has been realized in all the environments. The average radius of gyration, s̄, and the intrinsic viscosity, [η], decline with increasing concentration of the additives. This and the narrow pseudoternary single‐phase zones for both the carboxymethylcellulose (sodium salt)/CTAB (cetyltrimethylammonium bromide)

Systematic name: hexadecyltrimethylamounium bromide.

/ Triton X‐100 (α‐alkylphenyl‐ω‐hydroxypoly(oxyethylene))/water and the carboxymethylcellulose (sodium salt)/CTAB/Tween 20 (poly(oxyethylene)sorbitan monolaurate)/water system suggest instability of the polymer in presence of the additives. The spectral results indicate dye aggregation (stacking) on the flexible polymer chain. The binding of CTAB with the polyelectrolyte is Langmuirian in absence of KCl and strongly co‐operative in its presence. Thermodynamic parameters have been evaluated in the light of both Langmuir and Scatchard equations. Considering water and polymer to be in separate phases, the free energy of transfer of CTAB from the aqueous to the polymer phase has been calculated.
Crosslinking index, molecular weight distribution, and rubber equilibrium shear modulus during polyfunctional crosslinking of existing polymer, 1. Theory
Authors: te Nijenhuis Klaas
Published: April 2003

A statistical theory is presented, concerning polyfunctional crosslinking of polymer initially heterogeneous with respect to molecular weight. It is an extension of Flory's theory concerning tetrafunctional crosslinking. Relationships between the equilibrium shear modulus, the crosslinking index, the sol fraction, and the functionality of the crosslinks are given for uniform polymer and for non‐uniform polymer of unknown as well as known molecular weight distributions. It appears that at and just beyond the gel point, fractionation of the primary polymer has occurred in such a way that the number‐ and weight‐average molecular weights of the primary polymer molecules, present in the network fraction, are equal to the weight‐ and z‐average molecular weights of the original primary polymer, independent of the functionality of the crosslinks.
Polymers with pendant carbazolyl groups, 5. Photoconductive properties of some carbazole derivatives with electron donor and acceptor groups
Authors: Haarer Dietrich , Meyer Harald , Strohriegl Peter , Naegele Dieter
Published: April 2003

In this paper photocurrents of N‐isopropylcarbazole (NIPC) derivatives in polycarbonate hosts are reported and compared to data for a benzotriazole derivative (BTA). The carbazole moiety was substituted with both electron donor and acceptor substituents and the photoconductivity was measured as a function of concentration, electrical field, and temperature using the time‐of‐flight (TOF) technique. The observed increase of the effective mobility of charge carriers at low dopant concentrations upon substitution with a moderate electron acceptor is in contrast to literature data for some other materials. We interpret this increase as being due to an increase in the delocalisation radius of the transport state of the substituted carbazole molecule. The field dependence of the effective mobility shows Poole‐Frenkel behaviour, which is attributed to polaron formation. Comparison of the effective mobility of the NIPC derivatives with BTA shows that the size of the molecule plays a decisive role for the absolute value of the effective mobility.
New polymer syntheses, 51. Thermotropic homopolyesters of 4,4′‐dihydroxybiphenyl and substituted terephthalic acids
Authors: Kricheldorf Hans R. , Weegen‐Schulz Bettina , Engelhardt Jürgen
Published: April 2003

Polyesters were prepared from 4,4′‐dihydroxybiphenyl and various aryloxyterephthalic acids or various disubstituted terephthalic acids. The aryloxyterephthalic acids were prepared by nucleophilic substitution of dimethyl nitroterephthalate with phenoxide ions. The disubstituted terephthalic acids were synthesized by double alkylation of diethyl 2,5‐dihydroxyterephthalate with various alkyl bromides containing aromatic rings in the ω‐position. The silyl method was primarily used for the polycondensation procedure. The resulting polyesters were characterized by elemental analyses, viscosity measurements, wide‐angle X‐ray scattering and differential scanning calorimetry measurements, and by optical microscopy. All polyesters proved to be semicrystalline, meltable materials forming a nematic phase above their melting points. The substituents of terephthalic acid enhance the solubility in organic solvents, so that all polyesters are soluble in CH2Cl2/trifluoroacetic acid mixtures and some of them even in hot N,N‐dimethyl‐formamide or methyl benzoate.
New polymer syntheses, 52. Thermotropic copolyesters of various substituted terephthalic acids and 4,4′‐dihydroxybiphenyl
Authors: Kricheldorf Hans R. , Engelhardt Jürgen , Weegen‐Schulz Bettina
Published: April 2003

Various copolyesters were synthesized from 4,4′‐dihydroxybiphenyl and combinations of two or three differently substituted terephthalic acids. Various synthetic methods were studied; polycondensations of terephthaloyl dichlorides in dry pyridine gave the highest molecular weights. All copolyesters are semicrystalline and form a nematic melt above their melting points. Several copolyesters are well soluble in aprotic organic solvents, such as dichloromethane, N,N‐dimethyl‐formamide (DMF), methyl benzoate or chlorobenzene. A blend of such a soluble polyester (5 wt.‐%) with bisphenol‐A polycarbonate (poly(oxycarbonyl‐oxy‐1,4‐phenyleneisopropylidene‐1,4‐phenylene)) was prepared from a cosolvent and various mechanical data were measured. These data were compared with those of an aromatic thermotropic polycarbonate.
Polymer complexing equilibria. A new general approach based on the copolymerization equilibrium
Authors: Szymanski Ryszard
Published: April 2003

A new general treatment of the equilibria of complex formation between polymers and multivalent species (e.g. metal cations) is given. The treatment is based on the analysis of the equilibrium in the copolymerization of monomers and their complexes with multivalent species. An example of the analysis of experimental data for complexation of sodium tetraphenylborate with poly(oxyethylene) in methanol is presented.
Kinetics of the polymer‐analogous reaction of poly[(methyl methacrylate)‐co‐(methacrylic acid)] with epichlorohydrin
Authors: Sandner Barbara , Ziegler Hans‐Jörg
Published: April 2003

Poly[(methyl methacrylate)‐co‐(glycidyl methacrylate)] (poly(MMA‐co‐GMA)) was obtained by polymer‐analogous reaction of poly[(methyl methacrylate)‐co‐(methacrylic acid)] with an excess of epichlorohydrin (ECH) in the presence of a quaternary ammonium salt R4NX as catalyst. The kinetics of the addition reaction and the consecutive transepoxidation reaction was studied at 50–90°C. The rate constant of the addition reaction is one order of magnitude higher with E1 = 71 kJ · mol−1 than that of the transepoxidation reaction with E2 = 83 kJ · mol−1. The rate constants rise linearly with increasing concentration of the catalyst R4NX. The equilibrium constants K ≈ 2,3 of transepoxidation of glycidyl methacrylate (GMA) as well as of poly(MMA‐co‐GMA) both with 1,3‐dichloropropane‐2‐ol were determined in butyl acetate and dimethylformamide as solvent at 80–100°C. During the reverse transepoxidation reaction of 3‐chloro‐2‐hydroxypropyl methacrylate (CHPM) as well as of its MMA‐copolymer with equimolar amounts of ECH, side products were formed from the beginning of the reaction and the equilibrium was not established. The addition of ECH to CHPM was observed as a side reaction.
Cooperative structure formation by combination of covalent and association chain polymers, 3. Control of association polymer chain length
Authors: Hilger Christopher , Stadler Reimund
Published: April 2003

Thermoanalytical studies on an order‐disorder transition resulting from supramolecular organization of hydrogen bond motifs in an unpolar (polymer‐) matrix are reported. Functional groups having two potential sites for hydrogen bonding are located statistically along the polymer backbone. Multistep hydrogen bond formation leads to the formation of association chains whose lengths can be controlled by addition of monofunctional groups like in conventional stepgrowth polymers. The association chain length is estimated from the variation of transition enthalpy and ‘melting’ temperature.
Water‐swelling, hydrolyzable gels through polyaddition of H3PO4 to diepoxides
Authors: Nyk Andrzej , Klosinski Pawel , Penczek Stanislaw
Published: April 2003

Polyaddition of phosphoric acid to diepoxides, studied mostly with diepoxybutane (2), provides either soluble or insoluble (gels) polymers, depending on polyadditions conditions. Gels swell in water and slowly hydrolyze to soluble linear/branched polymers. These soluble polymers, prepared either directly or from hydrolyzable gels, hydrolyze further but much more slowly: some are stable for months, reflecting the difference of the rates of hydrolysis of predominantly tri‐(gels) and diesters (linear polymers) of H3PO4. Kinetic analysis of polyaddition and studies of the microstructure of the polymers indicate that one can influence the relative rates of addition of epoxy groups to POH and COH groups.
Carbonyl‐olefin exchange reaction. A new route to conjugated polymers, 6. Low‐molecular‐weight products
Authors: Jossifov Christo , Schopov Ivan
Published: April 2003

The processes which take place with the α,β‐unsaturated compound 1,2,3,3‐tetraphenyl‐2‐propen‐1‐one (1) under the influence of WCl6 were investigated. Special attention was paid to the low‐molecular‐weight products. It was established that beside polydiphenylacetylene and benzophenone also benzil, tetraphenylethylene and molecular oxygen are present in the product mixture. Their formation is explained as a result of a redistribution of the atoms connected with double bonds according to olefin metathesis (OM), carbonyl‐olefin exchange reaction (COER) and reductive coupling (RC) of carbonyl compounds, accompanied by molecular oxygen evolution. The yields of products insoluble in methanol are sometimes higher than a simple stoichiometry would allow. This can be attributed to the participation of both the inner double bonds of the polymer and the low‐molecular‐weight products.
Synthesis of polymers containing pseudohalide groups by cationic polymerization, 1. Homopolymerization of 3,3‐bis(azidomethyl)oxetane and its copolymerization with 3‐chloromethyl‐3‐(2,5,8‐trioxadecyl)oxetane
Authors: Cheradame Hervé , Andreolety Jean‐Pierre , Rousset Eliane
Published: April 2003

The cationic polymerization of 3,3‐bis(azidomethyl)oxetane (BAMO) was compared with the polymerization of 3,3‐bis(chloromethyl)oxetane (BCMO). The initiating system, boron trifluoride diethyl etherate/diethylene glycol (system. name: 2,2′‐oxydiethanol) was used and it was shown that unusually high concentrations were necessary to observe polymerization. NMR analysis of poly(BAMO), produced by this initiating system, suggested that BAMO polymerization proceeds through the activated‐monomer mechanism. The oligomer functionality, which was found close to 2, supports this suggestion. It was also shown that by copolymerization of BAMO with 3‐chloromethyl‐3‐(2,5,8‐trioxadecyl)oxetane the crystallization tendancy and the glass transition temperature of poly(BAMO) decreased.
Copolymerization of maleic anhydride with ethyl cinnamate and with anethole in chloroform
Authors: Fujimori Kijohisa , Schiller Wayne S. , Craven Ian E.
Published: April 2003

The composition of the copolymers of maleic anhydride (MA) with ethyl cinnamate (EC) and with anethole (ANE) polymerized in chloroform solutions with a radical initiator is reported. A strong alternating tendency is observed in the ANE‐MA copolymer but EC is incorporated dominantly into the EC‐MA copolymer. Both ANE and EC form 1 : 1 charge‐transfer complexes with MA with the equilibrium constants determined to be 0,0845 and 0,026 L/mol, respectively. Applicability of the terminal, the penultimate and the complex participation models of the copolymerization mechanism is examined by non‐linear least‐square minimization technique using the most general forms of the composition equations. The complex participation model is found to be slightly in favor for both EC‐MA and ANE‐MA copolymerizations in CHCl3.
Study of heterocyclic polymers, 3. Synthesis and properties of the ampholytic heteroccylic polyelectrolyte poly[n‐(2‐hydroxy‐3‐methacryloyloxypropyl)‐pyridinium‐3‐carboxylate]
Authors: Hsu Ying Gev , Hsu Miau Jing , Chen Keng Ming
Published: April 2003

A non‐betaine type of ampholytic heterocyclic polyelectrolyte (AHP), poly[N‐(2‐hydroxy‐3‐methacryloyloxypropyl)pyridinium‐3‐carboxylate] [poly(NHMPPC)], was synthesized by freeradical polymerization. The turbidimetric, viscometric and potentiometric properties of the polymer were studied in aqueous solution. It exhibits good salt tolerance in CaCl2 up to 100°C and a viscositiy behavior in aqueous alkali salt and hydrochloride solutions different from that of usual polyelectrolytes. The potentiometric behavior revealed that the polymer does not undergo a conformational transition during acidification and that the electrostatic repulsion along the chain is low. The polymer main chain forms compact hydrophobic areas in concentrated HCl solution, whereas in concentrated NaCl solution it extends to a more straight form.
Alternating copolymerization of butadiene and propene with the catalyst VO(ONeo)2 Cl/Al(i‐C4H9)3, 1
Authors: Arnold Manfred , Wohlfarth Lutz , Frank Willy , Reinhold Günter
Published: April 2003

The influence of basic reaction parameters—the ratio of catalyst components, the composition of the monomer mixture and the temperature—on the progress of the copolymerization, the molecular weight and the molecular weight distribution as well as on the composition of the copolymers obtained is reported. Conversion data for the variation of the mole ratio of comonomers show a maximum for an [Al]/[V] mole ratio of approximately 7, whereas the molecular weight of copolymers is not significantly influenced. An increase in the molecular weight of the copolymers can be obtained by an increase of butadiene content in the monomer mixture. However, there is also an increasing incorporation of butadiene into the copolymer. Raising the temperature from −60°C to 0°C results in a significant decrease in molecular weight, whereas the composition of the copolymers is not significantly changed.
A study of thermal oxidative and thermal mechanical degradation of polypropylene
Authors: Ying Qicong , Zhao Yong , Liu Yong
Published: April 2003

A study of the mechanism of thermal oxidative and thermal mechanical degradation of isotactic polypropylene (PP) is reported. Size exclusion liquid chromatography has been applied to the study of molar mass distribution (MMD) of samples of PP under oxidative degradation in the presence of an incorporated organic peroxide and of samples subjected to repeated extrusion. The change in MMD of the samples of PP under controlled oxidative degradation at 230°C is explained by a random chain scission mechanism and those of the samples of PP extruded repeatedly from an extruder at 280°C can be elucidated by a mechanism of mechanical chain scission with a threshold degree of polymerization 2L, below which the chain will not undergo scission. The value of L was found to be around 500.
13C NMR relaxation studies of poly(vinyl alcohol) and its derivatives
Authors: Egboh Sunday , Tenhu Heikki , Soljamo Kari , Sundholm Franciska
Published: April 2003

Spin‐lattice relaxation times (T1) have been measured by 13C NMR for poly(vinyl alcohol), poly(vinyl benzoate), poly(vinyl cinnamate) and poly(vinyl acetate) in dimethyl sulfoxide as a function of temperature and concentration. As expected, T1 increases with increasing temperature and decreases with increasing polymer concentration. The influence of the microstructure (tacticity) of the polymers on the relaxation times is negligible. T1 for the methine carbon of the polymer main chain is observed to serve as a measure of the rigidity and/or mobility of the chain. Assuming isotropic motion of the polymer chains, the activation energies for the protonated carbons were determined using the calculated correlation times.
Preparation and mesomorphic properties of new thermotropic liquid‐crystalline copoly(urethane‐carbonate)s
Authors: Sato Moriyuki , Hirata Tomohiro , Takeno Noboru , Mukaida Ken‐ichi
Published: April 2003

New thermotropic liquid‐crystalline (LC) copoly(urethane‐carbonate)s (4) with high inherent viscosities were prepared by melt polycondensation from 6,6′‐(4,4′‐biphenylylenedioxy)dihexanol (1) and a mixture of aliphatic bis(phenyl carbamate)s (2) and bis(phenyl carbonate)s (3) in high yields. The polymers characterized by FTIR spectra and elemental analyses show good solubilities in organic solvents such as chloroform. Flexible films were cast from the polymer solutions. Their thermotropic LC properties were evaluated by differential scanning calorimetry and observation under the polarizing microscope equipped with a hot stage. These measurements indicate that the polymers form stable LC mesophases and possess block‐like sequence distributions.
A new theoretical approach to problems of the solution behaviour of ring‐shaped polymers
Authors: Huang Jiaxian , Shen Jun , Li Chunrong , Liu Dongzhou
Published: April 2003

In order to explain the difference in theta temperatures between ring‐shaped polymers and their corresponding linear polymers, the Huggins parameters χ of ring‐shaped polymers is assumed to obey the dependence χ = χ1 (1 + σ ϕ2) on local segment concentration as expressed by the volume fraction of the polymer ϕ2, and σ being a constant. A comparison between theoretical results and light scattering measurements of Roovers and ourselves is satisfactory.
The role of H+ ions in the electrochemical polymerization of pyrrole
Authors: Qian Renyuan , Pei Qibing , Huang Zhitang
Published: April 2003

Pyrrole was found to polymerize electrochemically in a smooth and facile way when the immediate vincinity of the anode is at a pH of 3 ([H+] = 10−3 mol/dm3). The polymerization is inhibited by the presence of a H+ scavenger, di‐tert‐butylpyridine. Polymerization of pyrrole in a buffered solution of pH 4 gives a polypyrrole (PPy) film of slightly different chemical structure from that obtained in a buffered solution of pH 3, as shown by their IR spectra. No polymerization takes place in the buffered solution at pH > 7. These facts show the important role of H+ ions played in the electrochemical polymerization of pyrrole. Pyrrole might go through a protonated structure before it transfers an electron to the electrode, to form a cation radical which starts the polymerization. A new mechanism of polymerization is proposed in conformity with observed facts about the structure of PPy.
Solvent effects on free‐radical polymerization, 1. Solvent effect on initiation of methyl methacrylate and N‐vinyl‐2‐pyrrolidone
Authors: Czerwinski Wojciech Krzysztof
Published: April 2003

Initiation constant 2kd · f, dissociation constant kd, and efficiency factor f of AIBN were measured at 60°C for two model homopolymerization systems: methyl methacrylate (MMA) in N‐methyl‐2‐pyrrolidone (NMP) and N‐vinyl‐2‐pyrrolidone (NVP) in methyl isobutyrate (MiB) as the solvent. The stable Banfield radical was used as inhibitor. A pronounced solvent effect was observed on the side reaction of the inhibitor with the monomers. Particular solvent sensitivity of monomers in this reaction was identified, whereby opposite solvent properties of NMP and MiB as well as of MMA and NVP were found. The initiation constant 2 kd · f depends mainly on the dissociation constant of the initiator kd in regard to its solvent dependence. The efficiency factor f is influenced by monomer concentration, stability (reactivity) of primary radicals and by viscosity of the reaction medium (solvent cage effect).
Polymerization in inverse microemulsions, 3. Copolymerization of water‐ and oil‐soluble monomers initiated by radical initiators
Authors: Vašková Viera , Juraničová Viera , Bartoň Jaroslav
Published: April 2003

The copolymerization of acrylamide with methyl methacrylate or styrene in inverse microemulsion initiated by radical initiators with different solubility in water was studied in the initial stages of the reaction. It was found that the initial rate of copolymerization depends on the mole fraction of acrylamide in the comonomer mixture and is independent of the solubility of the radical initiator in water.
Determination of the microstructure of poly(chlorophenyl methacrylates) by 13C NMR spectroscopy
Authors: Hiller Wolf‐Gerald , Pasch Harald , Lampe Irene v.
Published: April 2003

Poly(chlorophenyl methacrylate)s with varying number and positions of the chloro substituent were prepared and investigated using 13C NMR spectroscopy. The tactic sequence distribution was determined from the signals of the carbonyl carbon (pentads) and the α‐methyl carbon atoms (triads). It was found that the polymers are predominantly syndiotactic with an average sequence length of between 3 and 4. The isotactic sequences accounted for a very small fraction of the polymer chain with an average sequence length of between 1,3 and 1,5. As for the signals of the aromatic carbon atoms it could be demonstrated that, depending on the substitution pattern of the aromatic ring, the sensitivity on sequence distribution was more or less pronounced.
Telechelic poly(ε‐caprolactone) terminated at both ends with OH groups and its derivatization
Authors: Sosnowski Stanislaw , Slomkowski Stanislaw , Penczek Stanislaw , Florjanczyk Zbigniew
Published: April 2003

The synthesis of highly uniform (1,08 ≤ Mw/Mn ≤ 1,13) telechelic poly(ε‐caprolactone) terminated at both ends with OH groups and its derivatization leading to poly(ε‐caprolactone) with pyrene end‐groups are described. The synthesis, carried out in THF at room temperature, involves initiation with (CH3CH2)2AlO(CH2CH2O)3Al(CH2CH3)2, leading to poly(ε‐caprolactone) macromolecules growing at both ends. The active centers were deactivated with acetic acid, giving macromolecules with OH end‐groups. Reaction of α,ω‐dihydroxypoly(ε‐caprolactone), HO‐poly(εCL)‐OH, with 4‐(1‐pyrenyl)butyryl chloride yields α,ω‐di‐1‐pyrenylpoly(ε‐caprolactone), Py‐poly(εCL)‐Py. Polymers are characterized by GPC, 1H NMR, and UV spectroscopies. The UV spectra of polymers with pyrene end‐groups are compared with the UV spectra of the model compound.
Preparation and polymerization of dimethylamino(methyl)styrenes
Authors: Kitayama Tatsuki , Masuda Eiji , Hatada Koichi
Published: April 2003

Three isomers of methylstyrene derivatives with a dimethylamino group in ortho position to the methyl group were prepared through the coupling reaction of the corresponding Grignard reagent and vinyl bromide using a Pd(0) catalyst, and their radical and anionic polymerization was examined. Monomer reactivity ratios in the radical copolymerization with styrene indicate that 3‐dimethylamino‐4‐methylstyrene (3‐DMA‐4‐MS) and 4‐dimethylamino‐3‐methylstyrene (4‐DMA‐3‐MS) have a higher reactivity than styrene, while the reactivity of 3‐dimethyl‐amino‐2‐methylstyrene (3‐DMA‐2‐MS) is lower than that of styrene. The 13C NMR chemical shift of vinyl carbons as well as the e‐values indicate that the electron density at the vinyl carbons of 3‐DMA‐4‐MS and 4‐DMA‐3‐MS is increased by the electron donating effect of the dimethylamino group, which results in lower reactivity of the monomers in anionic polymerization. The anionic copolymerization with 1,1‐diphenylethylene gave an alternating copolymer. In the anionic polymerization of 3‐DMA‐2‐MS, proton transfer reaction from the methyl group to the propagating chain end occurred to some extent to incorporate o‐phenylene units in the chain.
Thermal solid state polymerization of deuterated 2,4‐hexadiynylene di‐p‐toluenesulfonate: The topotactic reaction of topospecifically modified diacetylene derivatives
Authors: Gruner‐Bauer Petra , Müller Irene , Dormann Elmar , Kröhnke Christoph
Published: April 2003

The thermal solid state polymerization was analysed for topospecifically deuterated derivatives of 2,4‐hexadiynylene di‐p‐toluenesulfonate (PTS). Deuteration of the methylene groups close to the diacetylene‐monomer triple bonds influences drastically the length of the induction period and the reaction‐rate constants in the autocatalytic period. These peculiarities were investigated by the combination of dielectric permittivity measurements with differential scanning calorimetry and gravimetrical analyses of the solid state polymerization.
Modification of isotactic poly(propylene) with a nitrogen plasma; differences in comparison to the treatment with a carbon dioxide plasma
Authors: Poncin‐Epaillard Fabienne , Chevet Bruno , Brosse Jean‐Claude
Published: April 2003

The modification of isotactic poly(propylene) by nitrogen plasma treatment was studied in comparison to the use of a carbon dioxide plasma, which was reported earlier. The effect of the modification was characterized with secondary ion mass spectrometry (SIMS) to a depth of 3 Å, with electronic spectroscopy for chemical analysis (ESCA) to a depth of 20 Å and with attenuated total reflection Fourier transform infrared spectroscopy (ATR‐FTIR) to a depth of 10 μm: the nitrogen plasma modification seems to be milder than the CO2 plasma treatment. Surface degradation is a minor reaction, and in an opposite manner, crosslinking and functionalization (formation of primary amino groups) are the most important reactions. Radicals, probably originating from the elimination of [methyl groups] along the polymer backbone, could induce these reactions.
Graph theory of configurational and viscoelastic properties of polymers, 7. Chains containing large copolymeric blocks
Authors: Yang Yuliang
Published: April 2003

The graph theory of configurational and viscoelastic properties of polymers developed by the author is extended to treat chains containing large copolymeric blocks. The analytical expressions of zero‐shear‐rate viscosity, η0, and the radius of gyration weighted by the friction coefficients of beads, 〈S2〉ρ, of AB and ABA type block copolymer chains are obtained.
Synthesis and properties of quasi‐rigid polyesters containing 2,5‐disubstituted tetrahydropyran rings in their main chains
Authors: Atsumi Miharu , Okada Masahiko , Sumitomo Hiroshi , Yamada Satoru
Published: April 2003

A polyester composed of trans‐2,5‐linked tetrahydropyran rings (4t) was synthesized by direct polycondensation of trans‐5‐hydroxytetrahydropyran‐2‐carboxylic acid (5t) using N‐methyl‐2‐chloropyridinium iodide or triphenylphosphine and hexachloroethane as condensing agents in pyridine at 25 or 50°C. The hydroxycarboxylic acid 5t was polymerized also with dibutyltin oxide, although longer reaction times were required. The polyester 4t is soluble in m‐cresol and halogenated protic solvents such as 2,2,2‐trifluoroethanol, trifluoroacetic acids and dichloroacetic acid, but insoluble in chloroform and dichloromethane in which the corresponding cis‐isomer (4c) composed of cis‐2,5‐linked tetrahydropyran rings is soluble. According to conformational energy calculations, the repeating unit exists predominantly as a conformer in which both the exocyclic oxygen and the carbonyl carbon in the backbone of the chain are located in the equatorial positions of the tetrahydropyran ring; in other words, the chain of 4t takes a linear conformation. On the other hand, the exocyclic oxygen in the repeating unit of 4c occupies an axial position of the tetrahydropyran ring and the chain is winding. Conformational energies for dimer models for 4c and 4t were also estimated by means of force field calculations. These polyesters are partially crystalline according to their X‐ray diffraction patterns. Both polyesters show birefringence at or above 200°C. The polyesters 4c and 4t decompose at 300°C in nitrogen atmosphere, approximately 150°C higher than the isomeric polyester 2.
Propene polymerization with a Mg(OC2H5)2‐supported TiCl4 catalyst, 3. The role of benzoyl chloride
Authors: Jeong Young‐tae , Lee Dong‐ho , Shiono Takeshi , Soga Kazuo
Published: April 2003

The catalyst systems Mg(OC2H5)2/benzoyl chloride (BC)/TiCl4 and Mg(OC2H5)2/ethyl benzoate (EB)/TiCl4 were prepared for the polymerization of propene. In case of the Mg(OC2H5)2/BC/TiCl4 catalyst, BC changes into the internal donor EB during the in situ preparation of the catalyst and the unchanged BC acts as additional donor after reaction with triethylaluminium (TEA). Catalyst activity and isospecificity were also studied for the two catalysts by changing the amounts of BC or EB in the polymerization of propene cocatalyzed with TEA.
Fast living cationic polymerization of isobutyl vinyl ether and related vinyl ethers by C2H5AlCl2 in the presence of ClCH2COOCH3
Authors: Aoshima Sadahito , Shachi Kenji , Kobayashi Eiichi
Published: April 2003

Fast living cationic polymerization of isobutyl vinyl ether (IBVE) was examined using the initiating system 1‐(isobutoxy)ethyl acetate (1)/C2H5AlCl2 in the presence of various esters in hexane between 0°C and +40°C. Methyl chloroacetate as added ester turned out to be effective: the apparent polymerization rate constant k was larger by a factor of 400 – 500 than that in the presence of methyl acetate. The rate difference was explained on the basis of the basicity of the esters and their nucleophilic interaction with the propagating species. The polymers obtained in the presence of both esters had a narrow molecular‐weight distribution (MWD) (Mw/Mn ≤ 1,1), and Mn was directly proportional to monomer conversion. As low reactive monomers, 2‐chloroethyl vinyl ether (CEVE) and tert‐butyldimethylsilyl vinyl ether (SiVE) were polymerized under similar conditions. By selecting methyl chloroacetate as an additive, in the case of CEVE, fast living polymerization was achieved to give quantitative conversion within 10 min at 0°C; in the case of SiVE, polymers with a narrow MWD were obtained even at −20°C in high yield, whereas hardly any polymerization of SiVE occurred in the presence of methyl acetate.
The influence of the length of alkoxy side groups on the phase state of polydialkoxyphosphazenes
Authors: Tur Dzidra R. , Provotorova Natalia P. , Vinogradova Svetlana V. , Bakhmutov Vladimir I. , Galakhov Michail V. , Zhukov Valery P. , Dubovik Irina I. , Tsvankin Daniil Ja. , Papkov Vladimir S.
Published: April 2003

Polydialkoxyphosphazenes with different substituents varying from methoxy up to octoxy which contain only minor amounts (below 0,1 mol‐%) of various defective units in their macromolecules were synthesized. It was shown that such polyphosphazenes with propoxy, butoxy and pentoxy side groups can exist in the mesomorphic state and that a defect content as low as about 2 mol‐% prevents mesophase formation. In spite of high flexibility of the main chain, the polydialkoxyphosphazenes were found to gain the ability to crystallize only if the number of C atoms in the alkoxy substituents is higher than six.
Steric environments of radicals produced by addition of tert‐butoxyl radicals to dialkyl maleates as studied by spin trapping with 2,4,6‐tri‐tert‐butyl‐1‐nitrosobenzene
Authors: Yamada Bunichiro , Yoshikawa Eiichiro , Otsu Takayuki
Published: April 2003

Radicals produced by the addition of tert‐butoxyl radicals to maleic esters were spin‐trapped with 2,4,6‐tri‐tert‐butyl‐1‐nitrosobenzene (BNB). Although this does not yield polymers, the radicals resulting from the former addition were further added to maleate thus extending the chain length to a limited extent prior to the reaction with BNB. Increasing the bulkiness of the ester alkyl group and the chain length brought about considerable steric hindrance against the reaction with BNB as evidenced by an increase in the amount of N‐(alkoxy)phenylaminyl radicals in the spin adduct. The steric effect was found to arise already at the stage of short chain lengths (trimers): The radical consisting of two maleate units and bearing a tert‐butoxy end group seems to be less hindered than the longer homologues.
Telechelics via addition of dithiols onto diolefins, 3. Heat‐resistant polysulfides from 1,3‐benzenedithiol and norbornadiene
Authors: Nuyken Oskar , Völkel Thomas , Pöhlmann Thomas
Published: April 2003

The addition of an aromatic dithiol (1,3‐benzenedithiol) (3) onto a strained, unsaturated ring such as norbornadiene is studied. The average degree of polymerization depends on the stoichiometric ratio of the reactants. The functional end‐groups of the polymers are determined by the component used in excess. The resulting polymer is heat‐resistant up to 400°C. Non‐stoichiometric ratios of the reactants yield telechelics with thiol and vinyl end‐groups. By reaction with selected, suitable compounds a great variety of possible functional end‐groups can be obtained.
Emulsion polymerization of butadiene, 3. Kinetic effects of stirring conditions and monomer/water ratio
Authors: Weerts Pierre A. , Van der Loos Jos L. M. , German Anton L.
Published: April 2003

The stirring speed n influences the emulsion polymerization of butadiene, (1) by reducing the effective emulsifier concentration [E]eff available for particle nucleation and stabilization at high n, and (2) by limiting diffusion of monomer to the latex particles at low n. The large density difference between butadiene and water promotes the breaking up of droplets at high n, while the same condition constitutes a large driving force for (partial) phase separation at low n. Increasing the monomer/water ratio at constant [E] decreases [E]eff, and thus the final particle number. At monomer volume fractions >0,6 mixed emulsions are likely to be formed initially, reducing [E]eff even further. In the presence of mixed emulsions, polymerization in the monomer phase may no longer be neglected, giving rise to a complex kinetic behaviour.
Gas permeation through a side‐chain liquid‐crystalline polysiloxane‐based membrane
Authors: Chen Deng‐Shan , Hsiue Ging‐Ho , Hsu Chain‐Shu
Published: April 2003

A membrane was prepared by sandwiching the side‐chain liquid‐crystalline polysiloxane (LCP) 3 between two porous poly(propylene) (Celgard) films. Permeation properties for H2, O2, N2, CH4 and CO2 through the side‐chain LCP‐based membrane was measured using a gaschromatographic method at several different temperatures corresponding to the different states of the side‐chain LCP. The gas permeation behaviour depends strongly on the different states of the side‐chain LCP. The plots of permeability versus reciprocal temperature show an abrupt change of the slope in the vicinity of the glass transition temperature (Tg) of the side‐chain LCP for all five gases. The activation energy for permeation obtained at these different states exhibits different values. The value obtained in the liquid‐crystalline state is the highest. Separation factors (PO2/PN2) and (PCO2/PCH4) exhibit an unusual behaviour when the temperature changes across Tg. They increase abruptly when the temperature increases and the phase changes from the glassy state to the liquid‐crystalline state of the side‐chain LCP. The fact that both permeability and selectivity increases with increasing temperature above the glass transition is attributed to the supermolecular arrangement of the liquid‐crystalline state of the side‐chain LCP.
Regular folding in solution‐grown polyethylene crystal, 1. Model description
Authors: Chang Hwei‐Liang , Hu Andrew Teh
Published: April 2003

To re‐consider the idea that a polymer chain should fold regularly rather than randomly, the pair s‐chain crystalline growth philosophy was suggested. On the basis of this philosophy, the coordinated pair chain folding model (CPCFM) for polyethylene (PE) polymer single crystal is proposed, with the paired chain folding on average along the (110) plane of the orthorhombic crystal lattice and each of the coordinated pair chains folding alternatively at (100) and (010) planes. Being a regular folding model, the CPCFM explains most of the regular shapes of PE single crystals including lamellar diamond shape, flat based and non‐flat based hollow pyramidal shapes, saddle shape, truncated diamond shape as well as twin crystal via either the single‐chain nucleus or the two‐chain nucleus. The folding conformation energies for the folds in a CPCFM are lower than those for conventional adjacent (110) folds. The configuration and conformation mentioned above, together with other evidences, discussed in part 2 of this series and an earlier communication make the CPCFM an acceptable regular folding model.
Uniform tri(oxyalkylene)s. Preparation and characterisation
Authors: Bedells Alison D. , Mobbs Richard H. , Booth Colin
Published: April 2003

Methods for the preparation and purification of uniform tri(oxyalkylene)s from the C3 to C6 alkanediols are described. The preparation of the pure C3 trimer [α‐hydro‐ω‐hydroxy‐tri(oxytrimethylene)] is reported for the first time.
Oligomerization of 1‐hexene initiated by Zr(OnPr)4‐AlEt2Cl, 1. Influences of reaction parameters on kinetics and products' distribution
Authors: Liu Hua Qin , Deffieux Alain , Sigwalt Pierre
Published: April 2003

As part of our investigation of high α‐olefin oligomerization initiated by the complexation of a transition metal (Ti and Zr) compound with an organoaluminium derivative, the oligomerization of 1‐hexene initiated by Zr(OnPr)4‐AlEt2Cl was studied in detail at 20°C. It was found that a high mole ratio of [Al]/[Zr] (>5) was necessary in order to observe activity for 1‐hexene oligomerization. The highest activity was obtained for ratios ranging from 12 to 15. The products formed were mainly dimers, addition products of the ethyl group to 1‐hexene, and isomers of 1‐hexene. The corresponding saturated alkanes were also formed in large amount. Their relative percentage is proportional to the mole ratio of [Al]/[1‐hexene].
Preparation of sodium 13‐tetradecenoate and its polymerization under irradiation with UV light
Authors: Arai Kenichiro , Miyahara Shigeyoshi , Okabe Toshio
Published: April 2003

Sodium 13‐tetradecenoate(1) was synthesized as an amphiphile which contains a double bond at the chain end. The micelle formation behavior of 1 was examined by measuring the electric conductivity of its aqueous solutions; the pre‐critical micelle concentration (pre‐CMC) and genuine critical micelle concentration (CMC) were estimated to be 0,021 and 0,066 mol · L−1, respectively. Polymerization of 1 under irradiation with UV light was investigated; only a small amount of polymer was obtained at concentrations below the pre‐CMC, while this amount increased rapidly with increasing concentration of 1 above the pre‐CMC. Pre‐CMC and CMC of the obtained polymer were also examined and found to be 2,8 · 10−4 and 4,5 · 10−3 mol · L−1, respectively. The number‐average degree of polymerization (D̄P̄n) of poly(1) was about 23, the value of which was nearly in accord with the aggregation number of monomer 1, which was estimated by means of measurement of osmotic pressure of aqueous solutions of monomer 1. These results are compared with those of sodium 10‐undecenoate.
Theoretical study of resonant microwave absorption by DNA in aqueous solution
Authors: Fisun Oleg I. , Katanaev Michael O.
Published: April 2003

Theoretical analysis of resonant microwave absorption of cloned linear DNA in aqueous solution is given. To this end we calculate the absorption of electromagnetic waves by an ensemble of linear harmonic chains modelling DNA molecules in solution. The absorption depends crucially on the boundary conditions for the DNA molecules. To obtain proper boundary conditions the solvent is considered as a non‐Newtonian fluid of the second order in this frequency range. Calculated values of the resonant absorption coefficient are in agreement with recently found experimental data.
Langmuir‐Blodgett mono‐ and multilayers of preformed poly(octadecyl methacrylate)s, 1. Surface‐area isotherms of atactic and isotactic poly(octadecyl methacrylate)s and transfer into multilayers
Authors: Schouten Arend Jan , Wegner Gerhard
Published: April 2003

In order to elucidate some of the parameters controlling the transfer of compressed monomolecular layers of preformed poly(octadecyl methacrylate)s (PODMA) onto substrates by the so‐called Langmuir‐Blodgett technique, an investigation was undertaken of PODMA's of different tacticity and different molecular weights. For the preparation of multilayered structures it was necessary to decrease the interaction between the side chains. This could be accomplished by introducing side chain inhomogeneities especially in the form of comonomers with shorter alkyl side chains. The transferability of a monolayer could be correlated with features in the pressure‐area diagrams, as there is a liquid‐analogous state formed when shorter alkyl chains are introduced; moreover a partial “melting” with lowering of the collaps pressure of the layer is seen. It appeared that with isotactic PODMA regular Y‐type transfer

Y‐Type transfer: During one dipping and withdrawing cycle, two layers are transferred. Z‐Type transfer: Only during withdrawing one layer is transferred.

took place, whereas with the atactic polymers at the beginning a Z‐type transfer occurred, gradually changing into a Y‐type transfer. Applying the concept of decreasing interaction of the side chains it was possible to prepare multilayers of isotactic and atactic PODMA's.
Langmuir‐Blodgett mono‐ and multilayers of preformed poly(octadecyl methacrylate)s, 2. Structural studies by IR spectroscopy and small‐angle X‐ray scattering
Authors: Arndt Thomas , Schouten Arend Jan , Schmidt Günther F. , Wegner Gerhard
Published: April 2003

Langmuir‐Blodgett (LB) mono‐ and multilayers of preformed atactic and isotactic poly(octadecyl methacrylate)s were studied on gold surfaces and silicon wafers. The average orientation of the carbonyl bond of the ester group was found to be about 50° with respect to the normal to the substrate, and the side chains were concluded to be oriented perpendicular to the substrate. Furthermore, the degree of side chain orientation increased on going from a single monolayer to a multilayer. This is explained by an interdigitation of the side chains during or after the transfer process. A peculiar transfer behavior of the atactic samples is discussed in terms of the effect of disorder of the first layer on the transfer process. On heating multilayers of the polymers, melting of the crystalline domains formed by the side chains was observed at temperatures of about 35°C to 40°C. However, the layer structure appeared to be stable up to 100°C. The oriented structure was completely recovered after cooling down to room temperature.
Phenyl‐2,4,6‐trimethylbenzoylphosphinates as water‐soluble photoinitiators. Generation and reactivity of OṖ(C6H5)(O−) radical anions
Authors: Majima Tetsuro , Schnabel Wolfram , Weber Wilhelm
Published: April 2003

Lithium‐ and magnesium phenyl‐2,4,6‐trimethylbenzoylphosphinates (TMPPL and TMPPM) are effective water‐soluble photoinitiators for the free‐radical polymerization of appropriate monomers such as acrylamide (AA) and methacrylamide (MAA) in aqueous solution. They are also capable of initiating the polymerization of other olefinic compounds such as styrene (St), methyl methacrylate (MMA) or acrylonitrile (AN) in water‐containing solvent mixtures such as 1:1 water‐acetonitrile mixtures. This is due to the fact that TMPPL and TMPPM undergo α‐scission with a rather high quantum yield (ϕ(α) ≈ 0,35) resulting in the formation of 2,4,6‐trimethylbenzoyl radicals and OṖ (C6H5)(O−) radical anions. The latter are very reactive toward olefinic monomers. Bimolecular rate constants kR+M/(L/(mol · s)) were determined by flash photolysis at room temperature, e. g. in neat water: 3,8 · 108 (MAA), 2,2 · 108 (AA), and in H2O/CH3CN (1:1, v/v): 1,8 · 107 (St), 1,2 · 108 (MMA), 8,4 · 107 (AN).
Whiskers of poly(4‐hydroxybenzoic acid) — preparative aspects
Authors: Kricheldorf Hans R. , Ruhser Frank , Schwarz Gert , Adebahr Thorsten
Published: April 2003

Polycondensation of 4‐acetoxybenzoic acid (4‐ABA) at 300–400°C involves side reactions yielding a difficult to be hydrolyzed fraction of modified poly(4‐hydroxybenzoic acid) (poly‐HBA). Such side reactions are the formation of diphenyl ether groups, Fries‐rearrangement, formation of ketene or acetic anhydride and, possibly, isomerization to 3‐hydroxybenzoic acid. These by‐products not only influence the properties of poly‐HBA, they also affect the crystal growth of needle‐like crystals (whiskers). Even small amounts of free 4‐hydroxybenzoic acid poison the crystal growth of whiskers. The reaction conditions required for their preparation were optimized at 400°C. Fibrcus whiskers with lengths ≥ 100 μm and length/diameter ratios > 50 were only obtained at low monomer concentrations (≤0,05 mol/L). It is demonstrated by differential scanning calorimetry, wide‐angle X‐ray scattering and NMR spectroscopy that these whiskers are the chemically and physically most perfect form of poly‐HBA.
Polymers of carbonic acid, 6. Polymerization of trimethylene carbonate (1,3‐dioxan‐2‐one) with complexation catalysts
Authors: Kricheldorf Hans R. , Jenssen Jörg , Kreiser‐Saunders Ingrid
Published: April 2003

Numerous bulk polymerizations of trimethylene carbonate (1,3‐dioxan‐2‐one, 2) were conducted at 90, 120 and 150°C. Tributyltin methoxide, tributyltin acetate, dibutyltin dibromide, tin(II) 2‐ethylhexanotate, bismuth(III) 2‐ethylhexanoate and zinc stearate were used as initiators. On the basis of GPC measurements with universal calibration, weight‐average molecular weights up to approx. 22000 were found. The chemical structure of the resulting polycarbonates was examined by elemental analyses and 1H NMR spectroscopy. In contrast to similar polymerizations of ethylene carbonate, either groups were never found. However, all polycarbonates contain a CH2OH end‐group. Furthermore, methylcarbonate, acetate, 2‐ethylhexanoate or stearate end‐groups were found. Cyclic oligomers were not detectable in the gel‐permeation chromatograms of reaction mixtures. IR spectra indicate complexation of the carbonyl group by the initiators. The reaction mechanism is discussed.