Abstract: Bis(tri-n-butyltin) oxide ((n-Bu 3 Sn) 2 O), bis(triphenyltin) oxide (Ph 3 Sn) 2 O), and di-β-butyltin dimethoxide (Sn(n-Bu) 2 (OCH 3 ) 2 ) were all shown to catayze the syndiospecific polymerization of racemic butyrolactobe ((±)-BL). Of these catalysts, the Sn(n-Bu) 2 (OMe) 2 system showed dramatically decreased polymerization times for correspondingly high monomer conversion. This catalyst system was used to form syn-PHB with an M n and syndiad fraction of 8.4x10 4 and 0.62, respectively.

Abstract: The first acyclic diene metathesis (ADMET) polymerization of carbonate containing monomers using the molybdenum catalyst, Mo(CHCMe 2 Ph)(N-2,6-C 6 H 3 -i-Pr 2 )[OCCH 3 (CF 3 ) 2 ] 2 is reported. Bis(1-hexenyl) carbonate, bis(1-pentenyl) carbonate, bis(1-butenyl) carbonate, and 4,4'-isopropylidenebis(phenyl 1-butenyl carbonate) sucessfully undergo ADMET homopolymerization. These reactions are initiated under bulk conditions and are continued in solution to produce polymers [OCOO(CH 2 ) m CH=CH(CH 2 ) m ] n (m= 2,3,4) and [OCOOPh-C(Me) 2 -PhOCOO(CH 2 ) 2 CH=CH(CH 2 ) 2 ] n

Abstract: Results in studies of photoinduced polymerizations for adhesive and coating applications are reported. The photoinduced polymerizations studied included anionic and hydrosilation (a polyaddition polymerization) reactions. In photoinduced anionic polymerization our studies for ethyl cyanoacrylate polymerization are described. The effects of the concentration of photoinitiator and inhibitor on the ethyl cyanoacrylate polymerization rate are discussed. In photoinduced catalytic hydrosilylation reactions, the effects of the catalyst concentration and staging irradaition are disclosed

Abstract: Unsaturated poly(carbosiloxane)s ([SiO(Me) 2 ] 2 Si(Me) 2 CH 2 CH=CHCH 2 ) n , [SiO(Me) 2 Si(Me) 2 (CH 2 ) 3 CH=CH(CH 2 ) 3 ] n , [SiO(Me) 2 Si(Me) 2 PhSiO(Me) 2 Si(Me) 2 CH 2 CH=CHCH 2 ] n and [(SiO(Me) 2 Si(Me) 2 [CH 2 ] 4 ) x SiO(Me) 2 Si(Me) 2 (CH 2 ) 3 CH=CH(CH 2 ) 3 ] n and The synthesis of unsaturated poly(carbosiloxane)s, a new class of were synthesized by bulk acyclic diene metathesis polymerization catalyzed by [(CF 3 ) 2 CH 3 CO] 2 (N-2,6-C 6 H 3 -i-Pr 2 )Mo

Abstract: The kinetics of the photoinitiated polymerization of aqueous micellar solutions of n-alkyl-dimethyl(vinylbenzyl)ammonium chloride surfactants (Cn-STY with n=8 and 16) have been investigated. The rate of polymerization was determined by dilatometry and was found to be proportional to the first power of the monomer concentration, [M], and to the half-power of the oil-soluble initiator concentration, [I]. A dependence of the polymer molecular weight on [I] -0.6 was observed. These scaling laws are close to those obtained for styrene emulsion polymerization. A mechanism is proposed and discussed in terms of micellar dynamics

Abstract: The polymerization of L,L-lactide was conducted in bulk at 120, 150 and 180°C. Hematin (1a), hemin (1b), 5,10,15,20-tetraphenylporphiniron(III) chloride, 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphiniron(III) chloride (3) and chlorophyllin (4a) were used as initiators. Moderate yields and moderate molecular weights up to 15000 were obtained. Gradual racemization was observed with increasing reaction time and temperature. The results obtained with chlorophyllin and benzylated chlorophyllin suggest an anionic polymerization mechanism for the former initiator. When rac-D,L-lactide was polymerized with hematin in bulk at 120, 150 and 180°C, yields up to 74% and molecular weights up to 104 were found. The polymerization of meso-D,L-lactide gave lower yields and molecular weights. Both 1H- and 13C NMR spectroscopy indicate the formation of nearly random stereosequences in all polymerization of rac- and meso-D,L-lactide.

Abstract: The effects of photoinitiator structure and variations in the experimental parameters on the rate and extent of the photoinitiated cationic polymerization of propenyl ether monomers were studied. It was found that the photoinitiators can be divided into two classes: those which exhibit an induction period and those which do not. It was demonstrated that in those propenyl ether polymerizations using iodonium salts and certain sulfonium salts which do not have an induction period, a free radical chain-induced decomposition of the onium salt takes place. The reactivity of a particular onium salt photoinitiator was shown to be related to its reduction potential. It was also shown that the structure of the monomer plays a major role in the free radical induced decomposition reaction. © 1993 John Wiley & Sons, Inc.

Abstract: Copolymer compositions are provided, including those which undergo less than ±1.0% bulk polymerization shrinkage and are useful as strain-free composites, high-strength adhesives, and precision castings. The copolymer compositions are formed from the cationic initiated polymerization of alicyclic spiroorthocarbonate monomers and epoxy resin monomers or comonomers. A preferred spiroorthocarbonate monomer is 2,3,8,9-di(tetramethylene)-1,5,7,11-tetraoxaspiro-[5,5]undecane. A preferred epoxy resin is a three component epoxy comonomer mixture of (i) diglycidyl ether of bisphenol A, (ii) 3,4-epoxycyclohexanemethyl-3,4-epoxycyclohexane carboxylate, and (iii) vinyl cyclohexene dioxide, preferably in a ratio of 5:4:1 by weight.

Abstract: An NMR study was conducted on the mechanisms of side reactions in anionic polymerization of acrylonitrile (AN) with di-n-hexylmagnesium as an initiator in mixed-xylene at 25°C. In the initiation step the metalation of AN monomer leads to deactivation of the initiator. In the propagation stage both chain transfer to an α-proton in propagating chain and metalation of monomer proceed in parallel with addition reaction of the AN monomer to the propagating chain. The former two reactions result in 1) formation of branching structures and 2) deactivation of active site, respectively. Some new NMR peaks resulting from above side reactions, which did not appear in 13C NMR spectra of radically prepared PAN, were assigned. According to the assignments in this work, the number-average molecular weight, Mn (330–5600) and branching density, which means the number of branching per 100 repeating units, were estimated for acetone-soluble or acetone-insoluble products.

Abstract: Cardanyl acrylate (CA), a monomer that yields crosslinkable copolymers, was synthesized by the reaction of cardanol with acryloyl chloride. A linear polymer was obtained by solution polymerization of the monomer in toluene using 0.8% AIBN as initiator. Upon removal of solvent, the polymer undergoes crosslinking on exposure to air (or UV light) to give an insoluble transparent film. However, in bulk and suspension polymerization the polymer undergoes in situ crosslinking in the absence of any crosslinking agent. The crosslinking reaction of soluble polymer on exposure to air at ambiant conditions was explained by the hydroperoxide theory

Abstract: The present invention provides an acrylic polymer containing no surfactant, having little limitation in the polymer composition and being superior in heat resistance, processing operation performance and fluidity, and also provides use of the polymer and a production process. An acrylic polymer of present invention is obtained by the bulk polymerization, contains an acrylic acid-based monomer unit as a main component in its structure and has a Mn of 1,000 to 1,000,000, a glass transition temperature of -80° C. or higher and a Mw/Mn ratio of 5 or less, and is appropriate for acrylic rubber, a pressure-sensitive adhesive, an alkali-soluble adhesive, an alkali-soluble film, an alkali-soluble injection molding or water ink. This polymer is produced by, in the presence of an inactive gas, carrying out the bulk polymerization of a starting material which contains a monomer component having an acrylic acid-based monomer as a main component and contains a sulfur compound of 0.001 to 20 parts by weight based on 100 parts by weight of the monomer component, and contains a polymerization initiator in the weight of one-third or less based on the sulfur compound.

Abstract: Difunctional acrylates and methacrylate monomers have been made which are high order smectic liquid crystal (or crystalline) at room temperature. This report discusses materials with the following structure: F–S–M–S–F, where F is a functional group, acrylate or methacrylate (A or M); S is a spacer (CH2)n(n), and M is a mesogen—in this case 4,4′-dioxybiphenyl (B). They are codified as BnA or BnM where n is the number of methylenes in the spacer. High conversion with high Tg can be obtained when polymerizing in the smectic state because the reactive end groups are concentrated in a small volume and can react well with little or no diffusion. B2A, B3A, B6A, B11A, and B3M were polymerized in the smectic state and compared to polymers made at temperatures where the monomers were isotropic. High conversion was obtained below final Tg—even then, probably because the polymers were ordered. All the polymers were studied by WAXD and dynamic mechanical spectroscopy. Solid-state NMR on B3A showed that there was very high conversion of the double bonds at all temperatures. B3A photopolymerized in the smectic state (60–76°C) produced a crystalline polymer with Tg = 185°C (1 Hz). When photopolymerized at 85°C, above the isotropization temperature (Ti), a poorly organized polymer was obtained with a Tg of 155°C (1 Hz). Monomers with an odd number of methylene groups as spacers were crystalline after polymerization. With an even number of methylene groups, they lost most of their crystallinity on polymerization below Ti, but retained a low order smectic structure. Similar structures were obtained with all the monomers when they were polymerized above Ti. There was little effect of polymerization temperature on Tg when the spacers had an even number of methylene groups. © 1993 John Wiley & Sons, Inc.

Abstract: A series of silicon-containing multifunctional oxetane monomers has been prepared and characterized These monomers were compared among themselves and with other oxetane monomers with respect to their reactivity in photoinitiated cationic polymerization

Abstract: Racemic D,L-lactide and meso-D,L-lactide were polymerized with four different initiators: Al(isopropoxide)3, AIEt3/neopentyl alcohol (1 : 1, mole ratio), AIEt3/(+)-menthol (1 : 1, mole ratio) and methylaumoxane. Most polymerizations were conducted in xylene at 60, 90 and 120°C, but at 60°C the yields were below 10%. 1H NMR end-group analyses revealed the formation of alkyl ester end-groups from all Al-alkoxide initiators, in agreement with an insertion mechanism. The highest molecular weights were obtained with the methylalumoxane initiator. The stereosequences of the isolated poly(D,L-lactide)s were analyzed by 1H and 13C NMR spectroscopy on the basis of tetrad effects. poly(D,L-Iactide)s prepared from racemic D,L-lactide suggest a stereospecific polymerization favoring syndiotactic growing steps. In the case of meso-D,L-lactide all polymerizations follow Bernoullian statistics. Transesterification is poor or absent at temperatures ≤ 120°C. However, random stereosequences may be obtained by bulk polymerizations at 180°C. DSC measurements revealed that the glass transition temperature mainly depends on the molecular weight and not on slight differences in the stereosequences.

Abstract: The synthesis of poly(l-lactide) (PLLA), poly(l-lactide-co-e-caprolactone), and poly(DL-lactide-co-e-caprolactone) by ring-opening bulk polymerization was investigated. Polymerization temperature had a significant effect on the PLLA molecular weight. At 184°C a polymer with a molecular weight of only 10 × 104 resulted. This was lower by a factor of 2 than that obtained at 103 and 145°C. The stannous octoate (SnOct) concentration, with a monomer/SnOct molar ratio in the range of 1,000 to 10,000, was not found to have a significant effect on the PLLA molecular weight. A heterogeneous structure in polymerized PLLA was observed. The intrinsic viscosity of poly(lactide-co-€-caprolactone), obtained at 130°C, monomer/SnOct molar ratio 5,000, and polymerization time of 30 hours, decreased with increasing €-caprolactone content within the first 9 wt% and then leveled off. Die-drawing of PLLA cylinders, for the purpose of increasing the polymer's mechanical strength, was unsuccessful due to the brittleness...

Abstract: Bifunctional catalysts for the living polymerization of isocyanates were synthesized. These catalysts were shown by kinetic and molecular weight experiments to contain two active titanium centers for chain propagation. The polymers obtained from these catalysts should be good models for once-broken worms. In addition, telechelic polymeric catalysts were synthesized and used to produce new well-defined siloxane-isocyanate triblock copolymers

Abstract: To explain the kinetic features of particle formation and growth in unseeded emulsion polymerization initiated by oil-soluble initiators, a mathematical kinetic model is proposed, based on the assumption that when initiator radicals or monomer radicals in the water phase enter monomer-solubilized emulsifier micelles, initiate polymerization, and propagate to a chain length which is long enough not to desorb from the micelles, the micelles are regarded to be transformed into polymer particles. It is demonstrated by comparing the experimental results obtained in the emulsion polymerization of styrene initiated by the oil-soluble initiator, 2,2'-azobisisobutyronitrile, with sodium lauryl sulfate as emulsifier that the proposed kinetic model satisfactorily explains the kinetic features such as the effects of initial emulsifier, initiator, and monomer concentrations on both the number of polymer particles produced and the monomer conversion versus time histories. © 1993 John Wiley & Sons, Inc.

Abstract: This invention relates to an improved polymerization free radical initiator delivery system for the polymerization of monomers containing olefinic unsaturation and to the preparation of the initiator which comprises dissolving a water insoluble free radical initiator and an excess amount of the polymeric product of the reaction in a mutual organic solvent having a boiling point below 140° C., in the presence of between about 1.0 and 100 wt. % of a surfactant based on weight of initiator and mixing the resulting solution to achieve uniform molecular distribution of initiator and polymer molecules in the surfactant/solvent mixture; removing the solvent to provide coprecipitated initiator/polymer microparticles and then diluting the coprecipitated microparticles with water under vigorous agitation to form a microparticle emulsion of low viscosity which is suitable as the initiator feed for contact with monomer in a polymerization reaction.

Abstract: In a process for preparing block copolymers of styrene or its equivalents on the one hand and of butadiene or its equivalents on the other hand by sequential anionic polymerization, in which a first monomer and the organometallic compound serving as initiator are first of all combined to form a reaction mixture and the reaction is continued until at least part of the first monomer has been consumed, and then at least one further monomer is added and is in each case partially or completely reacted, the polymerization is carried out continuously in a conventional manner in a tubular reactor, the reaction of in each case one monomer being carried out in each case in one reactor section and at least two reactor sections being separated by a mixing stretch.

Abstract: Reactive extrusion is the term used to denote a plastics processing method in which an extruder is used as a reactor for the continuous synthesis and modification of polymers. This paper describes the manufacture of polystyrene and styrene-isoprene copolymers by a reactive extrusion process: anionic “living” s-butyllithium-initiated bulk polymerization was performed in a co-rotating closely intermeshing twin-screw extruder. The results of the process analysis show that living polymerization of styrene can be performed in a screwtype reactor, despite the high reaction temperatures of over 200°C. The polystyrene melt can be modified in bulk with comonomers or coupling reagents immediately after polymer synthesis. Depending on the raw material, formulation, and process parameters, the process variants developed and analyzed at the Institut fur Kunststoffverarbeitung for homopolymerization of styrene, copolymerization of styrene-isoprene mixtures, and sequential polymerization of styrene and isoprene resulted in styrene polymers with widely differing structural characteristics and properties. For example, the copolymerization of styrene-isoprene monomer mixtures produced poly [isoprene-co-styrene)-b-styrene]. The sequential polymerization of styrene and isoprene led to poly(styrene-b-isoprene) contaminated with partly cross-linked low molecular weight polyisoprene. The polyisoprene content is presumably formed by side reactions due to the high reaction temperatures. © 1993 John Wiley & Sons, Inc.

Abstract: Short-wavelength near-infrared spectroscopy is evaluated as a method for monitoring the percent conversion of methyl methacrylate to poly(methyl methacrylate) in situ in a mold. To reduce lensing effects of the mold and Schlieren paterns caused as the reaction progrressed, the illumination beam was modified to pass through the sample twice, using a retroreflecting array. The major spectral change observed involved the conversion of the vinyl group of the methyl methacrylate monomer to the methylene groups of the polymer

Abstract: Methyl methacrylate has been polymerized in three-component o/w microemulsions made with the cationic surfactant dodecyltrimethylammonium bromide (DTAB). The effects of temperature type and concentration of initiator (AIBN or potassium persulfate), and surfactant and monomer concentration on polymerization kinetics are investigated. Final conversions and reaction rates increase with increasing monomer and initiator concentrations and with higher reaction temperatures. The rate of polymerization shows initiation and termination intervals, but no constant rate interval is observed. Both molecular weight and particle size decrease as the concentration of initiator increases, regardless of type of initiator. Latexes with small particle size ( 106) were obtained in all cases. Activation energies for the microemulsion polymerization of MMA with AIBN (10.3 kcal/mol) and KPS (13.4 kcal/mol) are smaller than that of bulk polymerization using AIBN (20 kcal/mol). © 1993 John Wiley & Sons, Inc.