bluuebunny/crossref_metadata_2025 huggingface dataset:
Star‐shaped polymers by living cationic polymerization, 6. Amphiphilic star‐shaped block copolymers of vinyl ethers with carboxyl groups: synthesis and host‐guest interaction
Authors: Kanaoka Shokyoku , Sawamoto Mitsuo , Higashimura Toshinobu
Published: April 2003

Amphiphilic star‐shaped polymers (5 and 6) of vinyl ethers (VEs), the arms of which consist of apoly(carboxylic acid)/poly(alkyl VE) AB block copolymer, were prepared on the basis of living cationic polymerization. Thus, a sequential living polymerization of a VE with a pendant malonate group [CH2  CHOCH2CH2CH(COOCH2CH3)2] and and isobutyl VE with HI/ZnI2 at −15°C in toluene led to a living block copolymer (3a), which was subsequently allowed to react with a small amount of a bifunctional vinyl ether [1; CH2  CHOCH2CH2OC6H4C(CH3)2‐C6H4OCH2CH2OCH  CH2] to give a star‐shaped block copolymer (4a). Alkaline hydrolysis of the ester functions of 4a, followed by neutralization, gave the amphiphilic star copolymer (5a, diacid form; \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \{ H\rlap{--} [CH}_2 {\rm CH(OCH}_2 {\rm CH}_2 {\rm X)\rlap{---} ]}_m {\rm \rlap{--} [CH}_2 {\rm CH(O}i{\rm Bu)\rlap{--} ]}_n \} _f - {\rm (core)}, $\end{document} X = CH(COOH)2) with hydrophilic poly(carboxylic acid) segments in the outer region, and subsequent decarboxylation led to the monoacid form 6a (X = CH2COOH). Amphiphilic star copolymers (5b and 6b; \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \{ H\rlap{--} [CH}_2 {\rm CH(O}i{\rm Bu)\rlap{---} ]}_m {\rm \rlap{--} [CH}_2 {\rm CH(OCH}_2 {\rm CH}_2 {\rm X)\rlap{--} ]}_{n'} \} _f - {\rm (core)}, $\end{document} 5b: X = CH(COOH)2, 6b: X = CH2COOH) with an opposite segment sequence(inner polyacid chains) were also prepared. The star copolymer 5b (m′ = 30, n′ = 10) was insoluble in methanol, in which the polymer 5a (m = 10, n = 30) with the opposite segment sequence was soluble, and both 5a and 5b as well as both 6a and 6b differed in solubility from the corresponding linear polymer. The amphiphilic polymers 5 and 6 were also found to interact selectively with guests with polar functional groups such as benzoic acid and benzylamine.
Reaction between carbon monoxide and a Ti‐polyethylene bond with a MgCl2‐supported TiCl4 catalyst system
Authors: Shiono Takeshi , Ohgizawa Masaaki , Soga Kazuo
Published: April 2003

The reaction between carbon monoxide and the Ti‐polyethylene bond was investigated by using a stopped‐flow polymerization method which can provide quasi‐living polymers with very low molecular weights. Ethylene polymerization was conducted with a typical MgCl2‐supported TiCl4 catalyst combined with triisobutylaluminium (Al(i‐C4H9)3) or Al(CH3)3. The quasi‐living polymers were introduced into either the heptane solution saturated with carbon monoxide or the heptane solution containing 13C‐enriched carbon monoxide at −78°C. The mixture was gradually heated up to room temperature. During this procedure, a small portion of the reaction mixture was taken out at −78°C, 0°C and at room temperature. The polymers produced were analyzed by means of Fourier‐transform infrared spectroscopy, gel‐permeation chromatography, proton nuclear magnetic resonance (1H NMR) and 13C NMR spectroscopy. The analytical data show that carbon monoxide is predominantly incorporated into the polymers as a ketonic carbonyl.
Investigations on the ring‐opening polymerization of cyclic ketenacetals
Authors: Klemm Elisabeth , Schulze Thomas
Published: April 2003

The synthesis of five‐membered cyclic ketenacetals was investigated. It was shown that 2‐methylene‐1,3‐dioxolanes have various properties of polymerization in dependence on the substituents in 4‐ and 5‐position. While 4‐methylene‐3,5‐dioxatricyclo[5.2.1.02,6]decane (1) polymerizes without ring opening to high‐molecular‐weight polyacetals, which are insoluble in common solvents, 4‐methylene‐8,9:10,11‐dibenzo‐3,5‐dioxatricyclo[5.2.2.02,6]undeca‐8,10‐diene (2) yields oligomers (number‐average molecular weight M̄n (vapour pressure osmometry) = 900–1500) with ring‐opened and non‐ring‐opend units.
New polymer syntheses, 72. Telechelic and star‐shaped poly(ether‐sulfone)s by polycondensation of 4‐fluoro‐4′‐trimethylsiloxy(diphenyl sulfone)
Authors: Kricheldorf Hans R. , Adebahr Thorsten
Published: April 2003

The homopolycondensation of 4‐fluoro‐4′‐trimethylsiloxy(diphenyl sulfone) (2) in bulk and its cocondensation with 4‐fluoro‐4′‐trimethylsiloxybenzophenone (1) yielded high‐molecular‐weight, amorphous (co)poly(ether‐sulfone)s. The cocondensation with 4,4′‐difluoro(diphenyl sulfone) (4) afforded telechelic oligomers or polymers with two fluorobenzophenone end‐groups. Cocondensation with 4,4′‐bis(2,4‐difluorobenzoyl)[diphenyl ether] (5) gave star‐shaped polymers with four branches. Cocondensation with 1,3,5‐tris(trimethylsiloxy)benzene (6) yielded star‐shaped poly(ether‐sulfone)s with three longer than calculated star arms. Cocondensations with 2,2′,4,4′‐tetrakis(trimethylsiloxy)benzophenone (7) did not result in the formation of star‐shaped polymers, but yielded telechelic linear poly(ether‐sulfone)s with two trimethylsiloxy end‐groups. It was found that rapid cyclization of the benzophenone derivative (yielding a bis(trimethylsiloxy)xanthone) precedes the polycondensation.
NMR imaging of polymer materials
Authors: Bl¨︁umich Bernhard , Blümler Peter
Published: April 2003

The principles of NMR imaging applicable to materials are reviewed, and examples of current developments given. Among the different types of materials, polymers are particularly suitable for NMR imaging, because they are rich in protons, the most sensitive NMR nucleus. While the spatial resolution in solid materials is restricted to dimensions larger than 50 μm, the interest in NMR as an imaging technique derives from the abundance of parameters, which can be converted to image contrast for localization and identification of material morphology, chemistry and physics. Particular progress has been achieved in imaging of polymer melts and liquids, where diffusion and non‐Newtonian flow are investigated as well as of elastomers, where composition, deterioration by thermal and mechanical aging, and stress distribution can be characterized.
Analysis of hydrodynamic data on polymethacrylates with mesogenic pendant groups
Authors: Netopilík Miloš , Bohdanecký Miloslav , Wehrstedt Carla , Ruhmann Ralf , Schulz Günter
Published: April 2003

Dilute solutions of poly{6‐[4‐(4‐methoxyphenoxycarbonyl)phenoxy]hexyl methacrylate} (1 a, structure‐based IUPAC name poly(1‐{6‐[4‐(4‐methoxyphenoxycarbonyl)phenoxy]hexyloxycarbonyl}‐1‐methylethylene)) were investigated by means of size‐exclusion chromatography (SEC), osmometry, light scattering, and viscometry. It was found that the universal calibration of SEC is not valid with this polymer and that dilute solution properties (intrinsic viscosity, second virial coefficient) are at variance with predictions from the two‐parameter theory of polymer solutions. The latter discordance is explained on the basis of the theory of hydrodynamic properties of wormlike chains which takes into account the effective diameter of the chain. The characteristic ratio (C ∞ = 15,1) and the Kuhn segment length (λ−1 = 28 · 10−8 cm) were estimated. The polymer‐solvent interaction parameter was shown to decrease in the series of solvents: 1,1,2,2‐tetrachloroethane, chloroform, tetrahydrofuran, N,N‐dimethylformamide. The interaction of the solvents with the side groups was shown to be the determining factor.
A novel imaging system by dye‐sensitized photooxidation of oxazole groups attached to a polymer backbone
Authors: Ito Hiromitsu , Ikeda Tomiki , Ichimura Kunihiro
Published: April 2003

Copolymers of 2‐(3‐methacryloyloxypropyl)‐4,5‐diphenyloxazole (3) with various monomers were prepared. It was observed that the oxazole rings attached to the copolymer backbone are converted efficiently to the corresponding triacylamino residues by photooxidation using meso‐tetraphenylporphin as a photosensitizer in solution and in a thin film of the polymer. This photoinduced transformation in a copolymer 5c having N‐isopropylacrylamide as a comonomer was found to be applicable to a positive working photoresist by development with an aqueous solution of amines to dissolve the exposed areas of the film. A new system for positive image formation by visible light is presented.
Poly(p‐phenylene)s with polar side groups, 1. Pd‐catalyzed synthesis, characterization and modification of poly(p‐phenylene)s bearing butoxymethyl side chains
Authors: Rau Iris Ursula , Rehahn Matthias
Published: April 2003

This is a description of the Pd‐catalyzed synthesis of two poly(p‐phenylene) (PPP) derivatives which have butoxymethyl side groups on each, or every alternate, phenylene moiety. For the latter, details are given of the quantitative transformation of the ether functionalities into bromomethyl pendant groups. Subsequent reaction of these bromo functionalities with sodium 4‐cyanophenolate or sodium acetate produced structurally homogeneous PPP's which had 4‐cyanophenoxymethyl and acetoxymethyl side groups, respectively. The PPP derivatives described here are soluble in common organic solvents and were characterized in detail by NMR spectroscopy, membrane osmometry and size exclusion chromatography (SEC). The degrees of polycondensation of the butoxymethyl‐substituted polymers were found to be in the order of 30–65. No evidence for chain degradation during the following conversions was found on the basis of the NMR and SEC measurements.
Microstructure analysis of three segmented copolymers containing polydimethylsiloxane by solid‐state high‐resolution NMR
Authors: Feng Hanqiao , Shi Linqi , Feng Zhiliu , Shen Lianfang
Published: April 2003

The microstructure of two bicomponent and one tricomponent segmented copolymers, based on polydimethylsiloxane, poly(p‐hydroxystyrene) or/and polysulfone, were investigated using an extended Goldman‐Shen pulse sequence, proton spin‐spin relaxation measurements, and 13C and 29Si NMR spectra. The results indicate that there exist four phases with different sizes, components and morphological structure in the segmented copolymers studied in this work, i.e., a rigid‐chain phase of very slow motion, a rigid‐chain‐rich phase of slow motion, a flexible‐chain‐rich phase of fast motion and a flexible‐chain phase of faster motion. The sizes of different domains, calculated from the spin diffusion rates, are about 50–100 Å for the flexible‐chain‐rich phase of fast motion and 200–300 Å for the flexible‐chain phase of faster motion. The relative quantities of polydimethylsiloxane in the flexible‐chain phase of fast motion are slightly different in different kinds of segmented copolymers.
Effect of the external donors on the polymerization of 4‐methyl‐1‐pentene with high activity MgCl2/TiCl4 catalytic system
Authors: Frolov Ilia , Kleiner Vladimir , Krentsel Boris , Mardanov Robert , Munshi Kalyan , Bukatov Gennady , Zakharov Vladimir , Sergeev Sergey
Published: April 2003

In order to find out correlations between the structure of an external donor and the obtained polymer, the effects of different external donors on the activity and stereospecificity of the MgCl2/TiCl4 catalytic system in the bulk polymerization of 4‐methyl‐1‐pentene (4MP) were carefully studied. Different silane compounds of the structure RnSi(OR')4‐n (where: n = 1–3, R = alkyl/phenyl, R = alkyl) and Al(i‐Bu)3 (TIBA) were used as external donors and cocatalyst, respectively. The effect of the donor/TIBA mole ratio on the activity and stereospecificity of the catalytic system was studied. Some major effects were observed for the three different external donors, namely, Me3Si(OMe), Me2Si(OMe)2, and Me3Si(OBu)3, in the 4MP polymerization process. It was observed that the effect of the external silane donor on the polymerization strongly depends upon the size of the alkoxy and hydrocarbon (alkyl/phenyl) groups which are attached to the silicon atom. A selective deactivation of the non‐stereospecific centers, as well as a transformation of the non‐stereospecific into isospecific centers, is assumed to occur. On the basis of the obtained results and literature data available for the propene polymerization, the concept of structural conformity between the ligand‐surrounded active center and the monomer molecule was carried forward.
Synthesis of hydroxy‐terminated poly(vinyl ethers) by hydrogen chloride‐based living cationic polymerization
Authors: Hashimoto Tamotsu , Iwao Shigeki , Kodaira Toshiyuki
Published: April 2003

A new initiating system consisting of CH3CHCIOCH2CH2OCOCH3 (2, the hydrogen chloride adduct of 2‐vinyloxyethyl acetate) and ZnCl2 was applied for the synthesis of hydroxyterminated telechelic poly(vinyl ether). The 2/ZnCl2 was applied for the synthesis of hydroxy terminated telechelic poly(vinyl ether). The 2/ZnCl2 system induced living cationic polymerization of isobutyl vinyl ether in CH2Cl2 at −40°C to give a living polymer with a “head” (α‐end) acetoxy group originating from the initiator. Addition of an excess amount of water to the reaction mixture immediately terminated the living end to incorporate the “tail” (α‐end) aldehyde group. The obtained polymer exhibited narrow molecular weight distribution and end‐functionalities close to unity for both terminal functions. The treatment of the terminal groups with LiAlH4 led to a telechelic polymer with hydroxy end groups. Acetylation and subsequent structural analysis of the hydroxy polymer showed the existence of two hydroxy groups per polymer chain. Monofunctional poly(isobutyl vinyl ethers) with one hydroxy or aldehyde terminal were also obtained by similar hydrogen chloride‐based living cationic polymerization.
Polymerization by [3 + 2]‐cycloaddition, 5. Telechelics with isocyanate end‐groups
Authors: Maier Gerhard , Losert Klaus , Nuyken Oskar
Published: April 2003

The “criss‐cross” cycloaddition reaction between derivatives of benzaldehyde azine and several diisocyanates is used for the synthesis of polymers with an uncommon structure element: the 1,3,5,7‐tetrazabicyclo[3.3.0]octane‐2,6‐dione. The nature of the diisocyanate determines the reactivity in this cycloaddition polycondensation and the solubility of the new polymers. A degree of polymerization up to Pn = 72 could be achieved. Due to the nature of the polycondensation reaction, the polymers have two isocyanate end‐groups, independent of the stoichiometry of the monomer mixture at the beginning of the reaction. Thus, a prepolymer was synthesized and the chain extension by reaction of its isocyanate end‐groups with diamines was studied in some detail.
Copolymers of L‐ and D,L‐lactide with 6‐caprolactone: synthesis and characterization
Authors: Perego Gabriele , Vercellio Tiziano , Balbontin Giulio
Published: April 2003

L‐ and D,L‐lactide copolymers with 6‐caprolactone were synthesized and characterized in a wide range of compositions. The polymerizations were carried out in batch at 130°C, with Sn(II) octoate as a catalyst, a monomers/initiator mole ratio of 5000/1 and a reaction time of 48 h. The copolymers having from 5 to 40 wt.‐% of 6‐caprolactone are characterized by higher values of non‐reacted monomers and deviations of the polymer composition from the feed ratio. In the same interval of compositions, L‐lactide copolymers showed progressive hardening with time at room temperature, attributable to the tendency to crystallization of homopolymeric sequences. This behaviour was more deeply studied in the case of poly(L‐lactide‐co‐6‐caprolactone) with 30 wt.‐% of 6‐caprolactone. 1H NMR at 300 MHz appeared to be a suitable method for the determination of the monomer sequence.
Structure and electronic properties of polythiophene and poly(3‐alkylthiophene) films electropolymerized on indium tin oxide (ITO) glass at elevated potentials
Authors: Mårdalen Jostein , Samuelsen Emil J. , Gautun Odd R. , Carlsen Per H. J.
Published: April 2003

Homogeneous and flexible films of polythiophene are known to be difficult to obtain electrochemically on indium tin oxide (ITO) glass electrodes using normal 1,6–1,7 V applied voltage. The situation is greatly improved by using higher voltage. 0,1–10 μm thick films of polythiophene (PT) and various poly(3‐alkylthiophene)s (P3AT's) (alkyl = methyl (P3MT), hexyl (P3HT) and octyl (P3OT)) were electropolymerized on ITO‐covered glass anodes under an applied voltage of 8 V vs. an Ag/AgCl reference electrode. In this paper we report upon the properties of these films compared to their chemically and at low‐voltage electrochemically polymerized equivalents. Generally, the films have all the properties known for PT and P3AT's. Characteristics such as thermo‐ and solvatochromism, conductivity and electronic band structure as studied by ultraviolet photoemission spectroscopy and optical absorption were comparable to the properties shown by the reference samples. However, the structure of high‐voltage films differs considerably from those reported for chemically polymerized samples. The high‐voltage films contain a higher amorphous fraction, and the polymer is more cross‐linked and branched.
Micelle formation and anomalous behaviour in the system polystyrene‐block‐poly(ethylene/propene)/poly(isobutene)/5‐methyl‐2‐hexanone
Authors: Quintana José R. , Salazar Ramiro A. , Villacampa Manuel , Katime Issa A.
Published: April 2003

Solubilization of poly(isobutene)

Systematic IUPAC name: poly(1,1‐dimethylethylene).

by micelles of polystyrene‐block‐poly(ethylene/propene) block copolymer with a copoly(ethylene/propene) core was investigated. The weight of poly(isobutene) solubilized was found to be proportional to the concentration of block copolymer in the solution. No influence of the presence of poly(isobutene) on the critical micelle temperatures has been found. However, the addition of poly(isobutene) to the micellar solution seems to favour the anomalous behaviour found in micellar solutions of the block copolymers used in this study.
Side‐Chain liquid‐crystalline polymers containing a siloxane spacer, 2. Effects of mesogenic groups on the thermal properties of side‐chain liquid‐crystalline polymers containing a disiloxane unit in the spacer
Authors: Nagase Yu , Takamura Yuriko , Abe Hirokazu , Ono Kunihiko , Saito Takanori , Akiyama Eiich
Published: April 2003

A series of side‐chain Iiquid‐crystalline polymers was prepared containing disiloxane units in the spacer. The polymers consist of a polymethacrylate backbone and several kinds of mesogenic side groups. For the synthesis of the desired monomers, silanol compounds carrying a mesogenic groups were prepared as the intermediates. The polymers were obtained by ordinary free‐radical polymerization. As the mesogenic groups, linear‐type p‐ or p′‐substituted phenyl and biphenylyl benzoates, p‐ or m‐substituted benzoyloxybiphenyl groups and laterally attached biphenylyl benzoate‐type mesogens were chosen, and the structural effects on the thermal properties of the polymers were investigated. In the case of linear‐type mesogens, only when triple‐core mesogens were introduced a stable smectic mesophase was observed with a wide range of phase stability, while on mesophase was observed for the linear double‐core and the laterally attached mesogens. On the other hand, a highly ordered smectic phase was observed for polymers having linear‐type triple‐core mesogens with p‐alkoxy and m‐cyano end groups. Furthermore, it was revealed that the introduction of a disiloxane unit in the spacer lowered the temperature range of the mesophase, in comparison with polymers having an alkylene spacer with the same backbone component and mesogens.
Regio‐ and stereo‐selective alternating copolymerization of carbon monoxide with propene
Authors: Xu Frank Y. , Zhao Allen X. , Chien James C. W.
Published: April 2003

Compounds of palladium with ten different chelated bisphosphine ligands were investigated for their catalysis of alternating copolymerization of propene with carbon monoxide. The bisphosphine structure and chelate ring size influence strongly the activity, regio‐ and stereo‐selectivity of the catalysts. Molecular mechanics calculations on the π‐olefin complex showed that the non‐bonded interaction between propene and the ligands on Pd is both regio‐ and stereo‐selective. Primary insertion is about seven times more probable than secondary insertion for the Pd complex of bis(diphenylphosphino)butane ligand. The enantioselective catalysts favor the meso enchainment of propene. Gas chromatography/mass spectrometry (GC‐MS) of oligomers showed that most chains are initiated by PdH species with less frequent initiation by PdOCH3 complexes; β‐hydrogen elimination is the dominant chain termination process.
Polymeric protecting groups, 5. Polymerizable urea compounds with 2‐methylpropyloxycarbonyl function as a modified tert‐butoxycarbonyl‐type amino‐protecting group
Authors: Gormanns Marcus , Ritter Helmut
Published: April 2003

1‐[2‐(4‐chloroanilinocarbonyloxy)‐2‐methylpropyl]‐3‐methacryloylurea (4) was prepared by addition of 1‐(2‐hydroxy‐2‐methylpropyl)‐3‐methacryloylurea (3) to 4‐chlorophenyl isocyanate as a model compound. The new monomer 4 acts as a modified tert‐butoxycarbonyl (BOC)‐type amino‐protecting group which can be homopolymerized and copolymerized with methyl methacrylate (MMA) upon radical initiation. The kinetics of the deprotection of the aromatic amine under acidic conditions which leads to the formation of 2‐methacryloylamino‐5,5‐dimethyl‐Δ2‐1,3‐oxazoline (7) was followed by means of 1H NMR spectroscopy.
Copolymerization of propene and butadiene with MgCl2 supported titanium catalytic systems
Authors: Dassaud Jean‐Philippe , Guyot Alain , Spitz Roger
Published: April 2003

Upon copolymerization of propene and butadiene, using the recent generation of high mileage stereospecific MgCl2 supported TiCl4AIR3 catalytic systems, it is possible to incorporate a small proportion of butadiene units in polypropene, keeping reasonable, although strongly reduced, activity. The isospecificity of the catalysts for the propene polymerization is not affected, and even may be improved upon butadiene incorporation. The butadiene is incorporated in blocks of trans‐1,4 units. The amount of incorporation is dependent on the temperature, on the presence and then on the nature and concentration of a silane compound as an external Lewis base, and also on the nature of the alkylaluminium cocatalyst. The silane causes a small amount of 1,2‐butadiene units to be incorporated. The molecular weights of the polymers are strongly decreased but the crystallinity is only slightly affected.
Polymeric liposomes formed from a new phosphatidylcholine with terminal diene groups
Authors: Anikin Alexei , Chupin Vladimir , Anikin Michael , Serebrennikova Galina , Tarahovsky Jury
Published: April 2003

A novel polymerizable phospholipid with conjugated diene groups at the hydrocarbon chain ends, 1,2‐bis(11,13‐tetradecadienoyl)‐sn‐glycero‐3‐phosphocholine (7), was synthesized. This phospholipid gives liposomes which can be readily polymerized upon γ‐and UV‐irradiation. The conversion is up to 95% within 10 h at 60°C or within 3 days at room temperature. According to light scattering, 31P NMR and electron microscopy, the polymerized liposomes are detergent‐resistent and maintain their structure under ultrasonic treatment and in organic solvent media.
Liquid‐crystalline polysulfones, 3. New copolymers from 1‐alkenes with sulfur dioxide
Authors: Braun Dietrich , Arnold Norbert , Liebmann Andrea , Schmidtke Ingrid
Published: April 2003

A large number of new liquid‐crystalline 1‐alkenes with various mesogenic groups based on substituted phenyl benzoate or biphenyl and with different spacer lengths (2‐10 methylene groups) were synthesized and copolymerized with sulfur dioxide by free‐radical initiation to produce alternating polysulfones with liquid‐crystalline side chains. The phase transition temperatures of the 1‐alkenes and polysulfones were determined; their clearing temperatures lie in the ranges 43–138°C and 89–194°C, respectively. The liquid‐crystalline phases of the polysulfones, as determined by means of X‐ray diffraction, show a great variation, i.e. cholesteric and nematic as well as various smectic phases were obtained.
Blends of alkyloxy‐substituted liquid‐crystalline aromatic polyesters and copolyesters with poly(ethylene terephthalate)
Authors: Schleeh Thomas , Salamon Leszek , Hinrichsen Georg , Koβmehl Gerhard
Published: April 2003

Blends containing poly(ethylene terephthalate) (PET) and a series of alkyloxy laterally substituted liquid‐crystalline copolyesters (HTO5‐X series 1) in various ratios were prepared in the melt at 260°C by mechanical mixing. The visual and light microscopical appearance of the blends in the solid state and in the melt was found to be homogeneous for those blends which contained an aliphatic‐rich HT05‐X copolyester. The homogeneous appearance can be explained by a colloidal dispersion of the liquid‐crystalline polymer (LCP) in PET. Obvious phase separation in the melt occurs slowly after long periods of time. Phase separation is forced by annealing at about 270°C, where a change of viscosity is observed, and by shearing the sample. Characterization of theblends by DSC experiments shows that the thermal behaviour of all blends is dominated by the phase transitions of PET and that the LC‐low‐phase of the HTO5‐X copolyesters with a high degree of alkyloxy substitution is suppressed. The WAXS diffraction patterns of all blends contained an amorphous halo. For blends with low HTO5‐X concentration, inner reflexions from the nematic sanidic phase, as exhibited by the HTO5‐X copolyester, could be observed. For blends with higher HTO5‐X copolyester concentration, characteristic reflexions from HTO5‐X copolyester crystals could be observed. The number of X‐ray reflexions of the crystalline LCP in the blend is reduced compared to that of the pure LCP.
Vinyl polymerization initiated with the lanthanum versatate/p‐chlorobenzenediazonium tetrafluoroborate system
Authors: Sato Tsuneyuki , Toyosu Kentaro , Tanaka Hitoshi
Published: April 2003

The system of lanthanum versatate (1) and p‐chlorobenzenediazonium tetrafluoroborate (2) was found to induce effectively polymerizations of electron‐accepting monomers such as methyl methacrylate (3) and di‐2‐ethylhexyl itaconate (DEHI). The polymerization rate (Rp) was expressed by Rp = k[1/2]0,44 [3]0,65 at 50°C fixing the mole ratio of 1 and 2 at unity. The overall activation energy of the polymerization was calculated to be 37, 1 kJ · mol−1. The spin trapping result revealed that the initiator system produces p‐chloropheneyl radicals. The polymerization system of DEHI was observed to involve ESR‐observable propagating polymer radicals, indicating that the polymerization initiated with the 1/2 system proceeds through radical mechanism. During the polymerization, the ESR spectrum was changed in shape, suggesting that the propagating polymer radicals interact with some species formed by the initiation reaction. Interacting polymer radicals were also observed in the polymerizations of diethyl itaconate and N‐dodecylmaleimide with the 1/2 system. The polymerization systems of MMA, styrene and butyl acrylate were also found to involve ESR‐observable radicals, although it is vague whether they are propagating polymer radicals or not.
Intramolecular excimer formation in polyesters from terephthalic acid and six 2R,2R′‐propanediols
Authors: Mendicuti Francisco , Mattice Wayne L.
Published: April 2003

Fluorescence has been measured for six polyesters derived from terephthalate and six 2R,2R′‐propanediols, represented by HOCH2CRR′CH2OH. The solvent effects on the emission spectra permit separation of the six polymers into two groups. One group consists of the five polyesters in which R and R′ are alkyl groups, and the other group has only one member, that being the polyester with R = R′ = H. Modelling suggests that the origin of the difference between the two groups lies in the access by the polyester with R = R′ = H to a conformation (inaccessible when R and R′ are alkyl groups) that forms a very tight complex between two successive aromatic rings.
Rate coefficients for free‐radical polymerization of butyl acrylate to high conversion
Authors: Buback Michael , Degener Bettina
Published: April 2003

The free‐radical polymerization of butyl acrylate is studied between 25°C and 80°C at pressures up to 2500 bar. The reaction is measured by applying excimer laser techniques in conjunction with time‐resolved high‐pressure near infrared spectroscopy. Rate coefficients of propagation, kp, and termination, kt, are obtained for an extended temperature, pressure, and conversion range. The dependence of kt on conversion is analyzed by means of a kinetic model which considers segmental diffusion, translational diffusion, and reaction diffusion. It turns out that free‐radical termination is essentially determined by reaction diffusion.
Solvent effects on free‐radical polymerization, 5. Analysis of homopolymerization rate on the basis of the reactant‐solvent complex model
Authors: Czerwinski Wojciech Krzysztof
Published: April 2003

The rate of polymerization was described as a function of the monomer concentration of 36 monomer/solvent systems in terms of the reactant‐solvent complex (RSC) model. One‐, two‐and three‐parameter optimization procedures were used to fit the rate function to experimental data. Fitting increments were the complex equilibrium constant K and the relative monomer reactivity parameter r11. Irrespective of the optimization procedure, K and r11, were found to correlate with the monomer exponent n and to be K = 0 and r11, = 1 at n = 1. In these cases the RSC model reduces to the classical rate model. Despite the weak character of the monomer (radical)/solvent complexation, this interaction should not be neglected in rate modelling. The RSC model is a convenient tool to describe the chain propagation separately.
The miscibility and phase separation in binary blends of poly(vinyl chloride) with methyl methacrylate/acrylonitrile copolymers
Authors: Lath Dieter , Lathová Elena , Cowie John M. G.
Published: April 2003

The miscibility of poly(vinyl chloride) with poly(methyl methacrylate‐stat‐acrylonitrile) has been studied. Poly(vinyl chloride) is miscible with methyl methacrylate/acrylonitrile copolymers having acrylonitrile contents between 2,0 and 17 wt.‐%. All calculated binary segmental interaction parameters were positive, suggesting immiscibility of the corresponding binary homopolymer blends.
Photoinitiated cross‐linking of silicones, 10. Photoinitiated cross‐linking of silicone acrylates as studied by fourier transform infrared spectroscopy
Authors: Bajdala Jürgen , Müller Uwe , Wartewig Siegfried , Winkler Katrin
Published: April 2003

The photoinitiated cross‐linking of silicone acrylates is studied by FT‐IR spectroscopy. The influences of light intensity, exposure time and type of photoinitiator are described. The parameters of the kinetic equation are determined. It is shown that oxygen acts as an inhibitor. The asymmetric CO stretching IR band of the uncross‐linked and cross‐linked system can be separated into two bands which are attributed to different conformations and geometric arrangements of the acrylate groups, respectively.
Elementary processes of the Ziegler catalysis, 7. Ethylene, α‐olefin and norbornene copolymerization with the stereorigid catalyst systems ipr[flucp]zrcl2/mao and me2si[ind]2zrcl2/mao
Authors: Herfert Norbert , Montag Peter , Fink Gerhard
Published: April 2003

The stereorigid ansa‐metallocene catalysts [2,4‐cyclopentadien‐1‐ylidene(isopropylidene)‐fluoren‐9‐ylidene]zirconium dichloride/methylaluminoxane (iPr[FluCp]ZrCl2/MAO) and [(dimethylsilylene)bis(η5‐inden‐1‐ylidene)]zirconium dichloride/methylaluminoxane (Me2Si[Ind]2‐ZrCl2/MAO) are different in respect to the symmetry and, therefore, to the behaviour of the stereospecifity, in the size of the angle between the planes of the π‐ligand systems and in the homopolymerization behaviour of ethylene and propene. The present paper concerns itself with comparing the investigations of the ethylene/α‐olefin and the ethylene/cycloolefin copolymerization with both catalyst systems. The main kinetic result for both catalysts is that the α‐olefins show an accelerating effect on the ethylene polymerization rate during the copolymerization whereas norbornene shows exclusively a rate‐decreasing effect. The acceleration effect can be explained by an increase in the concentration of active centres and/or an increase of the rate constant of the ethylene insertion. The analysis of the microstructures of the formed copolymers by the use of statistical models demonstrates that in copolymers with a high content of α‐olefins, the experimental trial distributions can only be described satisfactorily with second‐order Markovian statistics. That means that in this case the last two monomers have influence on the insertion of the subsequent monomer. A further main result of all investigated copolymerizations is that the r‐parameters for the α‐olefin insertion are more favourable for the system iPr[FluCp]ZrCl2/MAO than for the system Me2Si[Ind]2ZrCl2/MAO; the reason for this is the different size in the coordination gap aperture of the π‐ligands. Furthermore, the r‐parameters show only a small dependence on the chain length of the α‐olefin. Finally, it is remarkable that the stereospecifity (syndiotactic or isotactic α‐olefin blocks) remains intact in the copolymers.
Synthesis of polyureas by polycondensation of diamines with active derivatives of carbonic acid
Authors: Katsarava Ramaz D. , Kartvelishvili Tamara M. , Japaridze Nona N. , Goguadze Tsisana A. , Khosruashvili Tamara A. , Tiger Roald P. , Berlin Pjotr A.
Published: April 2003

New polycondensation reactions of active diphenyl carbonates and diphenyl carbamate with diamines were developed for the synthesis of high‐molecular‐weight polyureas. The kinetics and mechanism of carbonic acid active esters aminolysis model reactions were studied. Possible side reactions including nucleophilic substitution reaction were investigated as well. It is shown that novel methods advantageously distinguish from traditional methods of polyureas synthesis by low tendency to side reactions and facilitate the synthesis of linear polyureas and copolyureas. It is found that N,N′‐bis(trimethylsilylated) diamines and salts of diamines as monomers can be successfully used in these reactions. Bioanalogous polymers promising for biomedical application — polyureas based on L‐lysine — were synthesized using novel polycondensation reactions.
Molecular design of biodegradable functional polymers, 3. Biodegradability and functionality of poly[(sodium acrylate)‐co‐(vinyl alcohol)]
Authors: Matsumura Shuichi , Ii Sawako , Shigeno Haruo , Tanaka Toshiyuki , Okuda Fumiko , Shimura Yukimasa , Toshima Kazunobu
Published: April 2003

As a design for a biodegradable functional polymer, compositionally homogeneous poly[(sodium acrylate)‐co‐(vinyl alcohol)] [P(SA‐co‐VA)], containing varying amounts of vinyl alcohol groups as biodegradable segments were prepared and their biodegradability and builder performance in detergent formulations were analyzed with respect to the successive vinyl alcohol length. It was found that the acrylate copolymers having more than 80 mol‐% vinyl alcohol content showed biodegradability. That is, P(SA‐co‐VA) having a vinyl alcohol chain length of more than about 5–6 is cleaved by PVA‐degrading microbes. This indicates that the vinyl alcohol blocks, which act as biodegradable segments, should be incorporated into the polymer chain in such a manner that they are accepted as substrates by the PVA‐degrading enzymes.
Sequence‐specific conformer of peptide sequence Asn‐Pro‐Asn‐X in dimethyl sulfoxide: Synthetic and 1H NMR studies on peptides having Asn‐Pro‐Asn‐Ala sequence and their gly‐substituted analogs
Authors: Isokawa Shizuko , Narita Mitsuaki , Umemoto Kimiko
Published: April 2003

A series of small peptides consisting of the repeating sequence Asn‐Pro‐Asn‐Ala, and their Gly‐substituted analogs, having one of the Asn residues replaced by Gly, have been synthesized to investigate the role of Asn side‐chain amido groups in stabilizing the secondary structure of the Asn‐Pro‐Asn‐Ala tetrapeptide unit. Analyses of the 1H NMR data obtained in dimethyl sulfoxide (Me2SO) revealed that the secondary structure of the tetrapeptide sequence is stabilized by virtue of the two Asn residues preceding and following Pro. The sequence‐specific turn structure, which is proposed here as the most probable conformer for the tetrapeptide unit, contains at most three intra‐molecular hydrogen bonds: between backbone CO of Asn preceding Pro and backbone NH of Asn following Pro (inverse γ turn), between side‐chain NHE and backbone CO of the same Asn following Pro, and between side chain CO of Asn preceding Pro and backbone NH of X(Ala).
Liquid‐crystalline side group polyesters with definite lengths of flexible spacers in the main chain
Authors: Böhme Axel , Novotna Eva , Kresse Horst , Kuschel Frank , Lindau Jürgen
Published: April 2003

Liquid‐crystalline polymalonates with a definite distance between the contact points of two neighbouring side groups were synthesized. The mesogenic group is azobenzene with a terminal nitro‐substituent acting as an indicator for dielectric measurements. The influence of the number of methylene groups in the main chain on the polymorphism and the dielectric behaviour has been investigated. Generally, the thermal stability of the mesophases decreases when the main chain spacer becomes longer. The relaxation frequency for the reorientation of the mesogenic side group around the short axis increases with increasing number of methylene groups in the main chain in both, the isotropic and liquid‐crystalline phases.
Enzymes in polymer chemistry, 7. Lipase‐catalyzed esterification of carboxyl‐terminated methacrylic oligomers and copolymers with isopropyl alcohol and 9‐fluorenylmethanol
Authors: Pavel Konstantin , Ritter Helmut
Published: April 2003

The carboxylic group of the oligoester α‐(11‐methacryloylaminoundecanoyl)‐ω‐hydroxy‐oligo(oxyundecamethylenecarbonyl) (1) was enzymatically esterified with isopropyl alcohol and 9‐fluorenylmethanol, respectively, in the presence of the lipase from Candida cylindracea. Moreover, the oligoester 1 was copolymerized with styrene and subsequently esterified with isopropyl alcohol by the same lipase. The degree of esterification and transesterification was determined by 1H NMR spectroscopy. Esterification occurred almost quantitatively, together with some transesterification, in the case of isopropyl alcohol, whereas with 9‐fluorenylmethanol only a degree of esterification as low as 30% was achieved. The formation of the enzymatically esterified oligoester units was proved by FAB mass spectrometry.
Synthesis and molecular weights of metal poly(vinyl acetate)s, 5.
Authors: Cárdenas Galo T. , Muñoz César D.
Published: April 2003

Metal vinyl acetate (MVAc) colloids were obtained by cocondensation at 77 K of the monomer with several metals such as: Pd, Ag, Au, Zn, Cd, Ga, In, Ge, Sn, Sb and Bi. Some of these colloids are stable for months at room temperature (Au, Ag, Pd). The colloids were polymerized with different amounts of initiator (2,2′‐azoisobutyronitrile) at 65°C, and a wide range of viscosity‐average molecular weights (104 < M̄v < 106) were obtained depending upon the metal used. The particle size of these clusters dispersed in the polymer matrix is around 1400 Å. The polymers are stable even at 320°C, and the metal content is ranging from 0,01 to 0,96 wt.‐%. The color of the polymers depends upon the metal used.
Photochemical decomposition of triazenes. (Electron paramagnetic resonance study)
Authors: Staško Andrej , Adamčík Vladimír , Lippert Thomas , Wokaun Alexander , Dauth Jochen , Nuyken Oskar
Published: April 2003

In the photochemical decomposition of triazene RNNNR1R2 in CH3CN solutions, where R was (3‐HOOC, di‐HOOC, 4‐HOOC, 4‐CN)phenyl and R1, R2 were CH3, CH2H5, CH(CH3)2, CH2CH2OH, the corresponding phenyl‐substituted radicals were identified as 5,5‐dimethyl‐1‐pyrroline N‐oxide (DMPO) or (CH3)3CNO adducts. The reaction is described by a first‐order kinetics with a half lifetime of 7 s. If R was di‐3,5‐CON3‐C6H3, a nitrogen‐centred radical was found on radiation in the solid state as well as in CH3CN solution with DMPO as spin trap.
The synthesis of α‐tert‐butyl‐ω‐[p‐vinylphenyl]‐terminated poly(2‐methylpropene) macromonomers
Authors: Nuyken Oskar , Gruber Freddy , Pask Stephen D. , Riederer Alexander , Walter Michael
Published: April 2003

In this communication a novel synthetic route to α‐tert‐butyl‐ω‐[p‐vinylphenyl]xy1terminated poly(2‐methylpropene) (PIB) macromonomers (P3 (VB); P5) is described:
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and
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Attempts to synthesize such macromonomers in both one‐ and two‐step syntheses are described. The one‐step method using 4‐chloromethylstyrene/AlR3 as initiating system for the polymerization of 2‐methylpropene did not yield linear macromonomers but rather highly branched products. The alternative two‐step synthesis using 1‐(2‐bromoethyl)‐4‐chloromethylbenzene (BCB) or BCB/AgSbF, as initiator also failed to yield the desired products. Successful syntheticroutes, optimised on the basis of model experiments with low molar mass compounds, are also described for preparing the above macromonomers. Both of these routes involve isopropenylterminated PIB, which is easily assessible by Inifer technique followed by dehydrohalogenation. Friedel‐Crafts alkylation of phenol by the terminal olefin group of PIB, followed by subsequentesterification of the phenolic end‐groups with 4‐vinylbenzoyl chloride, affords the macromonomer P3(VB). Conversion of the terminal olefin group of PIB into a primary alcohol using 9‐bora[3,3, I]‐bicyclononane/H202, followed by esterification, yields the macromonomer P5.
Conversion of the polydiacetylene of bis(ethylurethane) of 5,7‐dodecadiyne‐1,12‐diol to a non‐thermochromic crystalline form by solvent extraction
Authors: Sandman Daniel J. , Downey Milton J. , Hankin Sandra H. W.
Published: April 2003

Exposure of crystals of the thermochromic polydiacetylene (PDA) of the bis(ethylurethane) of 5,7‐dodecadiyne‐1,12‐diol (ETCD) to the hot solvents chlorobenzene and N,N‐dimethylformamide results in the conversion of the material to a nonthermochromic form. The material resulting from chlorobenzene extraction retains its original shape and is crystalline. It was further characterized by differential scanning calorimetry, X‐ray powder diffraction, and Raman spectroscopy. Significant amounts of chlorobenzene are not retained in the extracted material. It is indicated that chlorobenzene extracts monomer and oligomer causing expansion of the lattice, some disordering of the polymer chains, and removal of the interactions which allow observation of thermochromism. The implications of these findings for the role of possible mechanical strains in the crystal structure‐thermochromism relationship in urethane‐substituted PDA crystals are discussed.
Cationic polymerization of α‐pinene with aluminium‐based binary catalysts, 2. Survey of catalyst systems
Authors: Higashimura Toshinobu , Lu Jiang , Kamigaito Masami , Sawamoto Mitsuo , Deng Yun‐Xiang
Published: April 2003

A series of metal halides (AlCl3, AlBr3, AlEtCl2, BF3 · OEt2, SnCl4, TiCl4, and WCl6) were employed in conjunction with antimony trichloride (SbCl3) for the cationic polymerization of α‐pinene in toluene at −15°C. The combinations of aluminium halides (AlCl3, AlBr3, and AlEtCl2) with SbCl3 gave high molecular weight oligomers (M̄n ≥ 700) in good yield (>80 wt.‐%) with low dimer contents (5–17 wt.%). The other metal halides, both in the absence and presence of SbCl3, gave large amounts (20–40 wt.‐%) of dimers along with low molecular weight oligomers. 1H NMR analysis of the obtained oligomers showed that they consist of two isomerized repeating units, one (1) unsaturated (with a cyclohexene ring) and the other (2) saturated (with a bornyl structure). The oligomers obtained with aluminium halides/SbCl3 contained higher amounts of unsaturated units 1 than those with aluminium halides alone. The higher the molecular weight, the larger the content of 1. Isomerization of α‐pinene slightly occurred in the course of the polymerization, and the structure of the isomers depended on the catalyst systems. These results show that the aluminium halide/SbCl3 binary systems promote the ring‐opening of the cyclobutane unit in α‐pinene to give higher molecular weight oligomers.
Hydration of poly(pyridiniumsulfonatopropyl betaines)
Authors: Galin Monique , Galin Jean Claude
Published: April 2003

The hydration of poly(2‐vinyl‐ and 4‐vinylpyridinium‐3‐sulfonatopropyl betaines) (P2VP‐SB (1) and P4VP‐SB (2)) was studied by sorption isothermal analysis (activity of water a = 0,14–0,98) and by differential scanning calorimetry (DSC, weight fraction of water <0,5). The sorption isotherms at 296 K are typical of a multilayer sorption process (Guggenheim‐Anderson‐De Boer equation): the number of site‐bound water molecules per monomeric unit is 1,33 and 1,59 for 1 and 2, respectively; polymer‐water mixing for indirectly bound solvation layers corresponds to a thermodynamically unfavourable process characterized by Flory's interaction parameter χ of 0,85 and 0,75 for 1 and 2, respectively (Takizawa approach); however, clustering of water molecules (Zimm‐Lundberg theory) is never observed. For 1, DSC allows to quantify three types of water: non‐freezable bound water (type I), 5,0 mol per monomeric unit; freezable bound water (type II), 5,5 mol per monomeric unit, showing a two‐peak melting endotherm at 267 ± 1 K and 271 ± 1 K; bulk free water (type III, melting temperature Tm = 274 K), emerging far before the saturation of all the binding sites for type II water. The poly(pyridinium zwitterions) display slightly decreased hydrophilicity with respect to their aliphatic quaternary ammonium homologues.
The ring‐opening metathesis polymerization of (±)‐5‐endo‐methoxynorborn‐2‐ene. Microstructure of the polymers
Authors: Ivin Kenneth J. , Lam Luk‐Mui , Rooney John J.
Published: April 2003

The title monomer (±)‐5‐endo‐methoxynorborn‐2‐ene ((±)‐5‐endo‐methoxybicyclo[2.2.1]‐hept‐2‐ene, 1) was polymerized by Ru‐, W‐, Ir‐, Re‐ and Mo‐based metathesis catalysts to yield polymers with cis contents ranging from 10% to 48%. An assignment of the 13C NMR spectra was made. No significant head‐tail bias was observed and no splitting due to tacticity could be positively identified.
Electron microscopy investigations of polyester‐polyurethane elastomers stained with ruthenium tetroxide
Authors: Schrader Sigurd , Li Xuan , Guo Fanxiu , Liu Yong , Luo Jijiang , Xu Duanfu
Published: April 2003

Microphase separation of as‐reacted polyester‐polyurethane samples based on α‐hydro‐ω‐hydroxypoly(oxyethyleneoxyadipoyl)/4,4′‐methylenedi(phenyl isocyanate)/1,4‐butanediol/2‐ethyl‐2‐hydroxymethyl‐1,3‐propanediol (mole ratio 1:3,2:1,9:0,1) was studied using transmission electron microscopy. A new staining technique was applied which uses ruthenium tetroxide vapour for the treatment of the polymer. Ruthenium tetroxide reacts preferably with the hard‐segment‐rich microdomains of the polyester‐polyurethane. Therefore, a well‐contrasted pattern is formed by staining which reflects the microdomain structure of the polymer. The hard‐segment‐rich microdomains have irregular, mostly globular shape, and their sizes range from about 2 to 8 nm.