Star polymers and block copolymers of 2-oxazolines using chloroformates as initiators

Polyfunctional chloroformates were applied to the polymerization of 2-phenyl-2-oxazoline and 2-methyl-2-oxazoline. The use of a trifunctional initiator, viz. the chloroformate of 2,2-bis(hydroxymethyl)-1-butanol, led to three-arm star polymers of 2-oxazolines. Two macromolecular initiators, viz. poly(ethylene oxide) with two chloroformate end groups (α-chloroformyl-ω-chloroformyloxypoly(oxyethylene)) with number-average molar masses 350 g/mol ≤ M?_n ≤ 6000 g/mol and α-chloroformyl-ω-methoxypoly(oxyethylene) with M?_n = 350 and 750 g/mol were applied for the synthesis of poly(2-oxazoline)-block-poly(ethylene oxide)-block-poly(2-oxazoline) and poly(2-oxazoline)-block-poly(ethylene oxide) copolymers, respectively.     

Dithiocarbamate telechelic polymers: Synthesis and block copolymerization

The iniferter method of Otsu was studied for the synthesis of polyvinyl block copolymers of relatively low molecular weight using tetramethylthiuram disulfide (TD) and benzyl N,N-diethyldithiocarbamate (BDC) as initiator. Considering the low quantum yield of dissociation (?_d) of TD (2,5 · 10^?3 in cyclohexane), TD was used as thermal initiator (95°C) for the synthesis of dithiocarbamate-polystyrene (TD-PS) telechelics. ¹³C NMR analysis of this TD-PS shows two ¹³C?S signals corresponding to two different end-groups: Et₂N? CS? S? CH(C₆H₅)? CH₂? and Et₂N? CS? S? CH₂? CH(C₆H₅)? . Several styrene polymerizations were also carried out in presence of azoisobutyronitrile (AIBN) as thermal initiator and TD as chain-transfer reagent. Depending on the mole ratio AIBN/TD, mono- and difunctional TD-PS's are formed, as evidenced by NMR analysis. These TD-PS's were used for the photochemical initiations of ethyl acrylate (EA), acrylic acid (AA) and methyl methacrylate (MMA). It is assumed that the quantum yield of dissociation of the dithiocarbamate end-group is equal to that of BDC (?_d : 0,06). TD-PS nonfunctional polymers were also prepared, either photochemically by dissociation of BDC, or thermally in presence of AIBN and BDC as transfer agent. They were used for block copolymerization with MMA. Inversely, TD-PMMA's were prepared in a first step; in this case ?_d = 0,026. They were then used for the polymerization of EA. The block copolymers were fractionated; their composition and molecular weights were determined by ¹H NMR and gelpermeation chromatography, respectively.     

Synthesis and copolymerization of macromonomers based on 2-nonyl- and 2-phenyl-2-oxazoline

Several macromonomers were prepared by cationic ring-opening polymerization of 2-nonyl- and 2-phenyl-2-oxazoline using different techniques of functionalization. Introduction of the unsaturated functional group directly via a suitable termination agent proved to be superior to the use of a phenol-functionalized initiator and to the introduction of hydroxyl end groups via hydrolysis of the reactive cationic chain end and subsequent esterification with methacryloyl chloride. The macromonomers were characterized by spectroscopic techniques as well as GPC. One of the 4-vinylbenzyl-terminated macromonomers was copolymerized with MMA in different ratios. The copolymerization parameter r₁ was determined to be 0.75. The resulting graft copolymers were characterized regarding number of grafts per chain, molar mass, and glass transition temperature.     

Polymer synthesis based on 2-(hydroxyphenyl)-2-oxazolines

2-(Hydroxyphenyl)-2oxazolines(p- and n-isomers 1a and 1b ) were used for the synthesis of various polymers. Cationic polymerization of 2-methyl-2-oxazoline initiated with the N-methyl 2 -oxazolinium species 3 , Derived from 1 , Gave telechelic poly(N-acetylethylenimine) ( 5 ) having a hydroxyl group of different reactivity at both ends. Anionic polymerization of ethylene oxide induced by the lithium salt of 1, 7 , produced a poly(ethylene oxide) macromer, 9 , having a ringopening polymerizable 2-oxazoline group. The copolymer from 9 and 2-phenyl-2oxazoline, 10 , has been shown to have good properties as a nonionic polymeric surfactant in which the N-benzoylethylenimine main-chain behaves as a lipophilic group whereas the oxyethylene graftchains act as a hydrophilic group. Di-salt 11 derived from 1 was polymerized to give polymide 13 (“amphi-ionic polymerization”).     

Polymerization of macromonomers, 3. Monomer reactivity ratios in radical copolymerization of poly(tetrahydrofuran) macromonomers with 2-vinylnaphthalene

Methacrylate-terminated poly(tetrahydrofuran) (MA-PTHF) and acrylate-terminated poly-(tetrahydrofuran) (A-PTHF) macromonomers (M₂) were radically copolymerized with 2-vinylnaphthalene (2-VN, M₁). The composition of copolymers was determined by UV spectroscopy taking advantage of the very high absorption coefficient (UV) of the monomeric units of 2-VN in copolymer. The monomer reactivity ratios r₁ and r₂ evaluated are as follows. MA-PTHF: r₁ =1,3 ± 0,21, ± 0,05; A-PTHF: r₁ = 2,5 ± 0,35, r₂ = 0,10 ± 0,05. These reactivity ratios were compared with those in the copolymerizations of 2-VN with the corresponding small monomers and were discussed in terms of polymer (hindering) effect and the concept of equal reactivity of growing chain.     

Copolymerization reactivities and electron structure of 2-alkyl-5-vinyltetrazoles

Three novel monomers: 2-ethyl-, 2-isopropyl- and 2-tert-butyl-5-vinyltetrazole were synthesized. The copolymerizations of these monomers and 2-methyl-5-vinyltetrazole with styrene and methyl methacrylate were examined and the corresponding reactivity ratios r₁, r₂ and the Alfrey-Price Q, e values estimated. The obtained results, together with IR, ¹H NMR and ¹³C NMR data and quantum-chemical calculations of vinyltetrazole molecules by the AM-1 method, indicate that the type and the size of the substituent does not essentially influence the reactivity of 2-alkyl-5-vinyltetrazoles in radical copolymerization with vinyl monomers.     

Synthesis and properties of macromonomers carrying phosphatidylcholine analogous and azobenzene moieties

Macromonomers 6a , b , carrying phosphatidylcholine analogous and azobenzene moieties as a photoresponsive pigment, were prepared from the reaction of 2-oxo-1,3,2λ⁵-dioxaphospholane derivatives 2 and poly[2-dimethylaminoethyl methacrylate] macromonomer 5. 6b shows a nematic phase. The mesogenic group is connected with the chromophore via a flexible spacer group. Phase transition temperatures were determined by measurement of the rapid change in conductivity of the solutions of the amphiphiles with the temperature. From the result of photoreversible cis-trans isomerization it can be concluded that 6b can possibly be used as a photoresponsive material of a membrane.     

Synthesis and properties of poly(1-alkyl-3-methylene-2-pyrrolidone)s

A series of α-methylene-N-alkyl-2-pyrrolidone monomers with varying length of the alkyl chain from C₁ to C₈ were synthesised. The monomers were subjected to free radical polymerisation to yield a range of polymers each with a different balance in hydrophobic/hydrophilic properties originating from the pyrrolidone moiety and the N-alkyl chain. The equilibrium water content of polymers crosslinked with ethylene dimethacrylate were found to decrease with increasing alkyl chain length. The glass transition temperatures of the polymers are reported ranging from 98°C to -5°C on going from the methyl to the octyl derivative. The thermal degradation of the polymers was studied using thermogravimetric analysis and pyrolysis gas chromatography-mass spectroscopy. The polymers were found to degrade at ca. 400°C predominantly via an unzipping mechanism. Pyrolysis at 450°C results in five products.     

Syntheses of telechelic oligo- and poly(carboxypiperazine)s

Poly(carboxypiperazine) is only accessible via low temperature polycondensation methods. The melting point of the polymer is higher than the temperature of its decomposition. Oligomers with piperidine end groups were prepared to determine the melting points of the pure polymer by extrapolation from the melting points of the oligomers. The decomposition temperatures were determined by thermogravimetry. These studies led to the design of meltable telechelics.     

Synthesis of novel chitin derivatives having poly(2-alkyl-2-oxazoline) side chains

Novel chitin derivatives having poly(2-alkyl-2-oxazoline) side chains, i.e., chitin-graft-poly(2-methyl-2-oxazoline) ( 4a ) and chitin-graft-poly(2-ethyl-2-oxazoline) ( 4b ), were synthesized by means of the reaction of ca. 50% deacetylated chitin ( 3 ) with living poly(2-methyl-2-oxazoline) ( 2a ) and poly(2-ethyl-2-oxazoline) ( 2b ), respectively. The reaction between amino groups of 3 and the oxazolinium active species of 2 was examined by changing molar ratios of the feed ([ 2 ]₀/[D -glucosamine units of 3] ₀, ranging from 1,0 to 9,9) under mild conditions (at 27°C in dimethyl sulfoxide (DMSO)). 4a having monodisperse poly(2-methyl-2-oxazoline) side chains on almost every D -glucosamine unit of the main chain was obtained in 35% yield. The number of poly(2-alkyl-2-oxazoline) side chains was roughly controlled by the molar feed ratio of 2 and 3 . 4 is soluble in water, N,N-dimethylformamide, and DMSO, and partially soluble in methanol, acetonitrile, and chloroform. 4 shows improved solubilities in organic solvents, compared with 3 or chitin. The molecular motion of 4b in aqueous solution was discussed by employing ¹H NMR analytical data measured with changing temperature and solvent. In D₂O and, especially, in DMSO, it is suggested that motion of the chitin backbone is restricted, compared with that of the poly(2-ethyl-2-oxazoline) side chain. The content of the side chain in 4 was calculated from the ¹H NMR spectra recorded in D₂O/CD₃CO₂D (vol. ratio 95:5) above 60°C.     

Synthesis and ion-coupling reactions of telechelic polystyrene having cyclic onium salt groups

A series of mono- and bifunctional polystyrenes ( 1 c and 1 ′ c ) having 1-methylpyrrolidinium salt end groups were prepared through sequential derivatization, i.e., tosylation and quaternization reactions, of prepolymers having 3-hydroxypropyl groups ( 1 a and 1 ′ a ) produced by end-capping reactions of the relevant living polymers. The 1-methylpyrrolidinium salt end group was found to undergo a selective ring-opening reaction at 100°C by nucleophilic attack of a benzoate counter anion introduced by ion-exchange reaction. The ion-coupling reaction of 1 c and 1 ′ c with poly(styrene-co-acrylate salt) was found to take place upon coprecipitation of an equimolar mixture into methanol to afford ionically linked pseudo-graft and network products, respectively. The subsequent heat treatment, converting the ionic bond into a covalent one, results in branched and crosslinked polystyrene with predetermined structural parameters.     

鉴别MMPI-2随机测图指标的研究

目的：考察鉴别MMPI-2随机测图的有效指标。方法：根据精神病障碍患者1278例(男623例，女555例)MMPI-2 VRIN、|F-Fb|、VRIN |F-Fb|、F Fb|F-Fb|四个一致性指标的分布情况，确定划界分；检验一致性指标划界分对随机MMPI-2测图的鉴别有效性。结果：四个一致性指标中以VRIN |F-Fb|、|F-Fb|单独使用效果最好，VRIN其次，F Fb |F—Fb|指标效果最差。结论：单独使用一致性指标效果较差，四个指标联合使用效果最好，可排除91．50％的随机MMPI-2测图。     

Synthesis of telechelic polysiloxanes, 3. Synthesis of aliphatic diamines and diimides

Telechelic oligo(dimethylsiloxane)s 6 and 7 with chloro-, cyano- or aminopropyl end groups were synthesized from the corresponding chlorodimethylsilanes 2a–c and α-hydro-ω-hydroxyoligo(dimethylsiloxane)s 4 and 5 . The ω-cyano derivatives 6b and 7b were reduced to the 4-aminobutyl derivatives 8a and 8b with LiAlH₄. 8a was subsequently transformed into 1,7-bis(4-maleimidobutyl)-1,1,3,3,5,5,7,7-octamethyltetrasiloxane ( 10 ) by reaction with maleic anhydride, via the intermediate dimaleamic acid 9 . The products were characterized by IR, ¹H, ²⁹Si, and ¹³C NMR spectroscopy.     

Synthesis of poly(N-tert-butylaziridine) macromonomers and graft copolymers with uniform side chains

Poly(N-tert-butylaziridine) (polyTBA) macromonomers with allylamino-, allyloxy- and methacrylate end-groups were synthesized via deactivation of living polyTBA with appropriate nucleophiles. The macromonomers were copolymerized with N-vinyl-2-pyrrolidone (NVP), 2-hydroxyethyl methacrylate (HEMA) and isoprene (Is). Two types of graft copolymers were obtained: the first one is constituted of hydrophilic backbone (polyNVP or polyHEMA) and hydrophobic uniform polyTBA side chains. The second type is composed of a flexible hydrophobic polyIs backbone and hard hydrophobic polyTBA side chains which, however, become water swellable after quaternization.     

On the kinetics of polymerization and copolymerization of poly(oxyethylene) macromonomers and styrene

The homogeneous and the dispersion polymerzation and copolymerization of methacryloyl-terminated poly(oxyethylene) (MMA-PEG) and of p-vinylbenzyl-terminated poly(oxyethylene) (St-PEG) macromonomers and styrene, initiated by a radical initiator, was investigated using conventional gravimetric and NMR methods at 60°C. The batch polymerizations in N,N-di-methylformamide and in ethanol/water were conducted to either low or high conversion. The fractional conversion rates of the solution polymerization and copolymerization indicate that the homopolymerizations of macromonomers involve steady-state conditions, whereas copolymerizations proceed under non-stationary conditions. The ratios of the rate constants for propagation and termination (k_p/k) for polymerization and copolymerization of MMA-PEG and St-PEG are by one order of magnitude higher than that for styrene. The increase in k_p/k is more pronounced in dispersion polymerization, which is ascribed to the decrease of both k_p and k_t. The rates of dispersion polymerization are proportional to the particle concentration. The number of particles increses up to 50% conversion. The particle growth is suggested to proceed via association of partcles and by propagation within polymer particles. The decrese of the number of radicals per particles as conversion proceeds is ascribed to the decrese of the growing radical activity and to the transfer of monomeric radicals to the continuous phase. The molecular weights correlate inversely with the particle size.     

Transformation of polyester chains into dicationically living ones and synthesis of telechelic co-oligomers thereof

Unliving chains of aliphatic polyester were transformed into dicationically living poly(THF)-block-polyester-block-poly(THF) chains, and four different telechelic triblock co-oligomers with primary, secondary, tertiary amine, and hydroxyl end-groups were synthesized. A novel approach to the exchange of hydroxyl or carbonyl ends of polyester for amino end-groups is described. The primary amine-terminated telechelic triblock was used to modify an epoxy resin to give a toughened product with high strength.     

1,3-Oxazoline intermediates in reactive processing applications, 1. Melt grafting of poly(ethene-co-methacrylic acid) with 2-substituted 1,3-oxazolines

A novel family of functional ethene copolymers with various side chains were prepared by melt grafting of poly(ethene-co-methacrylic acid), containing 3,00 and 4,25 mol-% of methacrylic acid, with 2-substituted 1,3-oxazolines such as 2-phenyl-1,3-oxazoline, 2-undecyl-1,3-oxazoline, 2-heptadecyl-1,3-oxazoline, and 4-(1,3-oxazolin-2-yl)phenyl 4-methoxybenzoate. ¹H NMR and FTIR studies of the polymer microstructures revealed that carboxylic acid groups reacted with 1,3-oxazolines within few minutes to form esteramide-coupled side chains in very high yields. Torque of the reaction mixture, mechanical and thermal properties of the graft copolymers were measured. In the case of 2-heptadecyl-esteramide-substituted polyethenes, the side-chain cocrystallization accounted for higher crystallinity of the resulting graft copolymers.     

Simultaneous production of rhamnolipids, 2-alkyl-4-hydroxyquinolines, and phenazines by clinical isolates of Pseudomonas aeruginosa.

Of 72 clinical isolates of Pseudomonas aeruginosa examined for simultaneous production of secondary metabolites, 86% produced 2-alkyl-4-hydroxyquinolines, 75% produced rhamnolipids, and 58% produced phenazines, including pyocyanin. Whereas isolates producing two or one constituted smaller groups, 39% released all three metabolites. Metabolite production did not appear to influence site of infection.     

Recent results on functional polymers and macromonomers of interest as biomaterials or for biomaterial modification

Different families of functionalized polymers with potential as biomaterials, or for biomaterial modification, have been investigated. In particular, degradation studies have been performed on poly(amidoamines), a family of polymers obtained by polyaddition of amines to bisacrylamides, and endowed with heparin-complexing ability. Some new poly(amidoamines) with more resistance towards hydrolytic degradation than traditional ones have been discovered. Other ter-amino polymers deriving from the polyaddition of ter-amino functionalized bis-thiols to bis-acrylic esters, or other activated unsaturated compounds, have been studied. Their quaternarization products have been proven, in a parallel work, to act as powerful antimicrobial agents. By performing in situ the polyaddition reaction, semi-interpenetrated networks based on silicone rubber and the same polymers have been prepared. Finally, end-functionalized amphiphilic oligomers have been prepared by radical polymerization techniques, and their use for enzyme modification considered. Biomaterials (1994) 15, 1235–1241