Synthesis of graft copolymers by ring-opening polymerization of 2-nonyl-and 2-phenyl-2-oxazoline initiated by macroinitiators containing benzylchloride functions

Graft copolymers with poly(2-nonyl-2-oxazoline) and poly(2-phenyl-2-oxazoline) graft arms have been synthesized using the "grafting from" method. Slightly branched statistical copolymers of isobutene and (m,p)-chloromethylstyrene, synthesized cationically, as well as linear homo-poly((m,p)-chloromethylstyrene) have been used as macroinitiators for the ring-opening polymerization of the substituted oxazolines. The graft copolymerizations were carried out in bulk and in benzonitrile solutions with and without addition of potassium iodide. The influence of the reaction conditions on the rate of polymerization and the different reactivities of 2-nonyl-2-oxazoline and 2-phenyl-2-oxazoline were discussed. Received: 26 February 1997/Revised: 26 March 1997/Accepted: 14 April 1997     

Anionic polymerization of vinylsilanes VII

Summary. The anionic polymerization of tetravinylsilane (TeVS) was carried out in the presence and absence of N,N,N',N'-tetramethylethylenediamine (TMEDA). Without TMEDA, the polymerization proceeded extremely slowly and the polymer yield was still low even after an extended polymerization time. When TMEDA was added to the system, the polymerization was remarkably accelerated and gelation was suppressed. Such polymerization behavior of TeVS is closely similar to that of methyltrivinylsilane under similar conditions. The effects of TMEDA are explained by its coordination to the propagating end that increases the selectivity in the reaction of the propagating end with vinyl groups. Received: 29 March 1997/Revised: 14 July 1997/Accepted: 18 July 1997     

Surface modification of poly(tetrafluoroethylene) film by plasma graft polymerization of sodium vinylsulfonate

Poly(tetrafluoroethylene) (PTFE) surface was modified by the graft polymerization of sodium vinylsulfonate, and the chemical composition of the graft-polymerized PTFE surface was analyzed by X-ray photoelectron spectroscopy. Peroxides were formed on the PTFE surface by a combination procedure of argon plasma irradiation and air exposure, and the graft polymerization of sodium vinylsulfonate was initiated by the peroxide groups at 65–80°C. The peroxide concentration is 3 × 10⁺¹³ to 5 × 10⁺¹³ numbers/cm². The average degree of polymerization of the graft polymers was 3.4 × 10³. The graft polymer is distributed over the PTFE surface, but part of the PTFE surface remains uncovered. The coverage with the graft polymer is 43%. The PTFE surface graft polymerized with sodium vinylsulfonate was somewhat hydrophilic, but the hydrophilicity was lower than that of the PTFE surface modified by plasma treatment. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 77–84, 1997     

Synthesis and characterization of N-phenylmaleimide-methylvinylisocyanate copolymers with polystyrene side chains

Summary N-Substitued maleimide-methylvinylisocyanate copolymers with high glass transition temperature (T_g) was prepared and reacted with 4-hydroxy TEMPO (4-hydroxy-2,2,6,6-tetramethyl piperidinoxy) to yield polymers possessing stable radical at the side chain. The resulting polymers behaved as polymeric counter radicals for the radical polymerization of styrene. Thus, stable free radical mediated polymerization at the side chain was achieved. The resulting graft copolymers were characterized by spectral and thermal analysis. Received: 6 October 1999/Revised version: 7 March 2000/Accepted: 7 March 2000     

High-content polystyrene latex by microemulsion polymerization

The semicontinuous addition of styrene to a low solid-content (6 wt%) polystyrene latex obtained by polymerization of a three-component microemulsion, allows the production of a high solid-content latex (ca. 40 wt%) containing small particles (< 40 nm) of high molecular weight (> 10⁶ g/mol). The method can be extended to latex made from microemulsions containing other water-insoluble monomers. Received: 20 January 1997/Revised: 21 March 1997/Accepted: 27 March 1997     

P.psyllium-g-polyacrylamide: Synthesis and characterization

Summary To graft acylamide (AM) onto the backbone of natural water-soluble polysaccharide of P.psyllium mucilage (PSY), ceric ion initiated solution polymerization technique was reported for the first time. This technique was found to be beneficial. The effects of varying concentration of AM and ceric ammonium nitrate (CAN) on graft copolymerization have been studied. The prepared copolymers were characterized by FTIR. The % grafting and the intrinsic viscosity of this water-soluble copolymer were found to be affected by the concentration of AM and CAN in the reaction mixture. Received: 29 March 2002 / Revised version: 7 May 2002 / Accepted: 22 May 2002     

Asymmetric polymerization of N-triphenylmethylmaleimide with chiral anionic initiators

Asymmetric polymerization of N-triphenylmethylmaleimide (TrMI) is performed with chiral anionic initiators in tetrahydrofuran and toluene at − 78 and 0 °C to obtain optically active polymer. It is found that the (S)-(+)-1-(2-pyrrolidinylmethyl) pyrrolidinelithium [Li-(+)-PMP] and lithium (−)-menthoxide are effective for the asymmetric polymerization of N-triphenylmethylmaleimide in THF. The polymers obtained are characterized by circular dichroism (CD). It is inferred that the propagation reaction of polymerization of TrMI with Li-(+)-PMP is dominated by ion pair mechanism and meanwhile free ion mechanism cannot be ignored based on GPC analysis. Received: 6 December 1996/Revised: 24 February 1997/Accepted: 3 March 1997     

A new approach to anisotropic conductive networks

A liquid-crystalline bifunctional monomer with two different reactive moieties was prepared by esterification of 4-(6-(acryloyloxy)hexyloxy)benzoic acid and 4-[11-(3-thienyl)undecyloxy]-4′-hydroxybiphenyl. A mesogenic side-chain polyacrylate containing a thienyl moiety at the extremity of its side chain was obtained by radical polymerization of the monomer. The subsequent reaction of the thienyl moiety with FeCl₃ leads to the formation of an anisotropic network with a poly(thiophene) unit. Received: 17 January 1997/Accepted: 5 March 1997     

Matrix-induced variation in kinetics and control of molecular weight of methacrylic acid polymers during graft copolymerization with starch

Polymerization of synthetic monomers is known to be influenced by the solvent, initiator system, dilution, temperature, etc. Substrates like starch granules, when used for graft copolymerization, can be expected to provide a drastically different environment for the monomers (as compared to the bulk of the solvent medium), and therefore we predicted this to influence the kinetics of polymerization and stereoregularity of the synthetic polymer. This was investigated with respect to polymerization of methacrylic acid with starch. The rate of methacrylic acid polymerization was found to be significantly higher in grafting with starch as compared to homopolymerization in the absence of starch. Control of molecular weight of the grafted chains was achieved by use of chain transfer agents, and the chain transfer constants for graft copolymerization were determined for two chain transfer agents. The polydispersity of the grafted chains was also found to be dependent on the chain transfer agents. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 397–403, 1997     

The role of complex formation in the anionic polymerization of l-lactide

The rate lowering effect of crown ethers in the anionic polymerization of l-lactide is interpreted by the formation of activated monomer-cation complex. This interpretation is supported by molecular mechanics calculations. The formation of a 1 : 1 complex between lithium ion and l-lactide in THF was proved by ¹H NMR and the formation constant was measured to be 3.8 M⁻¹. Received: 15 January 1997/Accepted: 10 March 1997     

Poly(α-t-butoxy-ω-styrylo-glycidol): a new reactive surfactant

Summary Poly(α-t-butoxy-ω-styrylo-ethoxy ethyl glycidyl ether) was synthesized via the termination of the potassium t-butoxide initiated anionic polymerization of ethoxy ethyl glycidyl ether with p-chloromethylstyrene. The macromonomer was copolymerized with styrene. Subsequent hydrolysis of the copolymers leads to polystyrene - graft - polyglycidol. Poly(α-t-butoxy-ω-styrylo-glycidol), synthesized through the hydrolysis of the macromonomer so obtained, acts as reactive emulsifier (surfmer) in the emulsion copolymerization of styrene in water. Received: 13 January 1998/Revised version: 24 February 1998/Accepted: 5 March 1998     

Separation of block copolymers from parent homopolymers by means of liquid chromatography at the critical adsorption point

The characterization of a block copolymer consisting of blocks of tetrahydrofuran, THF, and methyl methacrylate, MMA, was attempted with the aid of liquid chromatography, LC, at the critical adsorption point, CAP. The conditions applying to the CAP at 30 °C for the homopolymers are: PTHF: eluent composition: THF : acetonitrile = 50 : 50, w/w; column: Nucleosil C₁₈. PMMA: eluent composition: THF : n-hexane = 81.8 : 18.2, w/w; column: bare silica gel. The presence of homo PTHF and of homo PMMA in the crude block copolymer was evidenced. Moreover, chromatography at the CAP for PMMA showed that the block copolymer contains multiblock (triblock) fractions. The formation of triblock copolymer is expected when the polymerization of MMA is terminated (partially) by combination. In conclusion, LC at the CAP is a powerful tool to characterize block copolymers regarding the presence of homopolymer and multiblock (triblock) fractions. Received: 13 February 1997/Revised: 18 March 1997/Accepted: 24 March 1997     

Polymerization of ethylene by chromium acetylacetonate/methylaluminoxane catalyst system

Summary The present paper deals with polymerization of ethylene by chromium acetylacetonate - Cr(acac)₃ - activated by alkylaluminium, e.g. Al(C₂H₅)₃ or Al(i-C₅H₉)₃, or methylaluminoxane (MAO). The influence of polymerization parameters on catalyst performance, such as Al/Cr mole ratio, temperature, aging time, type of cocatalyst, was investigated. High activities were obtained only when MAO was the cocatalyst. The polymers were characterized by size exclusion chromatography (SEC) and differential scanning calorimetry (DSC) analyses. Received: 11 September 1997/Revised version: 5 January 1998/Accepted: 20 March 1998     

Preparation and evaluation of the chitin derivatives for wastewater treatments

The chitin thiocarbonate—Fe(II)H—H₂O₂ redox system was investigated as the initiator for the graft copolymerization of acrylonitrile and acrylic acid monomers onto chitin powder. The reaction with vinyl monomers onto chitin was carried out under various parameters of the graft copolymerization reaction to elucidate the polymerization behavior in terms of graft yield. Reactions of chitin—acrylonitrile graft copolymer with hydroxyl amine hydrochloride, as well as, sodium hydroxide were conducted in order to obtain chitin—(amidoxime-co-acrylonitrile) and chitin-(acrylate-co-acrylamide) graft copolymers, respectively. The reaction efficiency depends upon the alkali concentration, time, temperature, and on the reactant concentrations. The prepared chitin derivatives were evaluated for use in the wastewater treatments for adsorption and desorption of heavy metal ions as well as acid and basic dyes. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1939–1946, 1997     

Synthesis of graft copolymer of styrene and acrylonitrile onto poly (butyl acrylate) by using polymeric peroxide

Summary Two-stage seeded emulsion copolymerization of butyl acrylate with tert-butyl 3-isopropenylcumylperoxide (D120) was performed at 70°C . Copolymer latex with 0.2μm of particle size was obtained. Emulsion graft polymerization of styrene and acrylonitrile onto the copolymer of butyl acrylate was initiated by peroxy bonds in the D120 units of the backbone chains at 120°C . Graft copolymers with higher grafting ratio were derived. It was found that the grafting ratio tends to increase with the increasing D120 in feed of copolymerization with butyl acrylate. The graft copolymers were blended with SAN resin, and a kind of AAS resin was obtained. Both elongation at break and Izod impact strength of the AAS resin reached maximum at grafting ratio of 0.25, which were comparable with the values of ABS resin for general purpose. A method to improve the grafting efficiency on the saturated polyacrylate elastomer rubber was developed. Received: 6 March 2002 / Revised version: 8 May 2002 / Accepted: 13 May 2002     

Durable,hydrophilic surface modification of polypropylene films by plasma graft polymerization of glycidyl methacrylate

Summary The plasma graft polymerization of glycidyl methacrylate (GMA) was investigated to obtain hydrophilic surface. The combination of the argon plasma and GMA vapor exposures leaded to graft polymerization of GMA at the surface of polypropylene films. This graft polymerization was initiated by the argon plasma exposure for 2 min, and was accomplished with the GMA vapor exposure for 2 min. The GMA graft polymerization made polypropyrene surface hydrophilic. The surface energy was 55.8 mJ/m². The hydrophilicity introduced by the GMA graft polymerization remained for at least 3 weeks. The graft polymerization of hydrophilic monomers was a good means of hydrophilic surface modification.     

Synthesis of novel organoboron polymers by haloboration polymerization of bisallene compounds and their reactions

Summary. Novel organoboron polymers were prepared by haloboration polymerization of bisallene compounds. The polymers obtained have allylborane halide units in their main chain and can be expected as a novel type of reactive polymers. For example, the polymer prepared by haloboration polymerization between tribromoborane (1) and 1,2,10,11-dodecatetraene (2 b) was subjected to chain transformation reaction (dichloromethyl methyl ether rearrangement) to give the corresponding polyalcohol or polyketone. Haloboration-phenylboration polymerization of aliphatic bisallenes by using diphenylbromoborane also gave the corresponding polymers. Received: 8 July 1997/Revised: 23 July 1997/Accepted: 28 July 1997     

Synthesis of polystyrene/silica gel polymer hybrids by in-situ polymerization method

Summary. Homogeneous polystyrene and silica gel polymer hybrids were prepared by in-situ radical polymerization method. Styrene monomer was introduced into a sol-gel reaction mixture of tetramethoxysilane (TMOS) and the polymerization was initiated by Azobisisobutyronitrile (AIBN), while sol-gel reaction of TMOS proceeded to form a silica gel. The homogeneity of the hybrids was found to be dependent on the amount of the acid catalyst. The homogeneity was confirmed quantitatively by measuring porosity of charred hybrids with nitrogen porosimetry method. It was found that polystyrene was dispersed at a nano-meter level in the silica gel matrix. Received: 8 July 1997/Revised: 29 July 1997/Accepted: 1 August 1997     

PP固相接枝GMA微观聚合动力学研究

基于聚丙烯(PP)固相接枝聚合的终止反应主要是自由基单基终止反应的假设提出相应的接枝聚合机理,并建立聚合速率模型。实验考察了PP接枝甲基丙烯酸缩水甘油酯(GMA)体系单体浓度、引发剂浓度、聚合温度与聚合初期接枝速率的依赖关系。结果表明:初始聚合速率与单体浓度呈1.57次方、与引发剂浓度呈0.48次方关系,与聚合温度关系服从Arrhenius方程,并求得接枝反应的表观活化能Ea为86.63kJ/mol。     

Synthesis and bulk properties of poly(tetrahydrofuran)-poly(2-methyl-2-oxazoline) ABA triblock copolymers

A series of linear triblock-copolymers of the ABA type in which the central B-block is poly(tetrahydrofuran) (polyTHF) and the A-segments are poly(2-methyl-2-oxazoline) (polyMeOX) were synthesized by a one-pot sequential monomer addition copolymerization, utilizing the living nature of the cationic ring-opening polymerization of both monomers. Films of the copolymers, casted from chloroform solutions, exhibit excellent mechanical properties in comparison with the homopolymers with comparable molecular weights, which was ascribed to the phase separation occurring between the two copolymer segments. Materials, in which the polyTHF B-segment have a molecular weight 13 000 g/mol or higher and each polyMeOX A-block a molecular weight 1500 g/mol, kept elastomeric properties up to 130 °C notwithstanding the fact that this temperature is considerably higher than the melting point of polyTHF and the glass transition temperature of polyMeOX. It was found that these triblock-copolymer materials show a shape memory effect. These observations are attributed to the high degree of phase separation between the two blocks and the strong polar interactions between the polyMeOX segments. Received: 20 March 1997/Revised: 5 September 1997/Accepted: 8 September 1997