Abstract: The ring-opening polymerization of D, L-dilactide and an equimolar dilactide-diglycolide mixture has been investigated. Conversion and molecular weight in the lactide bulk polymerization are determined not only by the kinetics of the primary ring-opening reaction, but also by the concentration and extent of consecutive reactions of reactive groups in the polyester formed. High conversions and high molecular weights are obtained only by high polymerization rates. For the characterization of the polymers, viscosity-molecular weight relationships for monomer-containing ‘equilibrium’ polymers and reprecipitated polymers were determined. The application of these polymers in parenteral drug delivery systems for a gonadotropin-releasing hormone agonist has been investigated.

Abstract: It is confirmed that during the polymerization of 1,3-cyclohexadiene initiated by polystyryllithium in cyclohexane a tranfer to the monomer takes place, as previously reported. It is shown that a part of the metallated monomer reinitiates the polymerization and another part decomposes to inert lithium hydride. The formation of 1,4-cyclohexadiene is observed and interpreted. The transfer constant is deduced from measured molecular weights. The propagation constants were reported in a previous paper of this series. Knowing these values, the ratio between reinitiation and decomposition constants is deduced from a comparison between experimental kinetics and a numerical resolution of kinetic equations. This study allows a prediction of the best conditions for the synthesis of block copolymers including poly(1,3-cyclohexadiene) sequences in 1–4 addition.

Abstract: Preparation par reaction de la p-cyanopyridine avec les halogenures de benzyle correspondants puis par echange du contre anion avec SbF 6 − . Les 2 sels ont une activite d'amorceur de la polymerisation cationique du phenyl glycidyl ether superieure a celle de l'hexafluoroantimoniate de benzyl-1 cyano-4 pyridinium

Abstract: A precipitation polymerization process for the production of a macroporous cross-linked copolymer in which there is added to a reactor equipped with a stirrer, at least one monounsaturated monomer and at least one polyunsaturated monomer, dissolving an inorganic polymerization reaction initiator in a homogeneous minimum-boiling binary azeotrope including a solvent and water, and conducting the polymerization in the azeotrope.

Abstract: The grafting and the crosslinking of polybutadiene during the bulk thermal polymerization of high-impact polystyrene were studied. The kinetic equations for these two reactions were derived by the use of the moments of the distribution functions. This kinetic model indicates that both the density of grafting and the degree of crosslinking increase with the increasing temperature of polymerization and, most significantly, with the increasing conversion of styrene.

Abstract: PURPOSE: To produce a water-absorptive resin having a sharp molecular weight distribution and an improved absorption rate under normal and elevated pressure by subjecting an aqueous solution containing a hydrophilic vinyl monomer having a functional group and a crosslinking agent and a polymerization initiator to a polymerization reaction under specified conditions. CONSTITUTION: An aqueous solution of a concentration of 30-80wt.% containing a hydrophilic vinyl monomer (A) having a functional group [e.g. (meth)acrylic acid] and 0.0001-5wt.%, based on component A, crosslinking agent (B) [e.g. N,N-methylenebis(meth)acrylamide] and 0.0005-5wt.%, based on component A, polymerization initiator (C) (e.g. azobisisobutyronitrile) are fed to a polymerizer adapted so that the surface in contact with the aqueous solution may be heated and/or cooled. After starting the polymerization at 0-70°C, the aqueous solution is subjected to a constant-temperature polymerization reaction at 20-70°C without agitation, and the polymerization is accomplished by optionally heating it to 70°C or above after the conversion reaches 70% or above. COPYRIGHT: (C)1992,JPO&Japio

Abstract: The cationic polymerization of 2-chloroethyl vinyl ether initiated by HI/weak Lewis acid (I2 or ZnI2) systems has been studied from both a kinetic-mechanistic and a synthetic viewpoint. At low temperature and in toluene as solvent, the polymerization proceeds via a living process and the kinetic order with respect to monomer varies according to the nature of the Lewis acid activator. This behaviour can be explained by the coordination of the Lewis acid with both the monomer and the chain-end, the latter leading to a strong activation of the -I bond towards monomer insertion. The living polymerization obtained from divinylether precursors leads to -I ended telechelics, and their transformation into dihydroxytelechelic oligomers has been performed. The chemical modification of chloroalkyl side groups by phase transfer catalysis allows the attachment of specific groups without consumption of-OH ends.

Abstract: The reaction of trimethylsilyl iodide (TMSI) with 1,3-dioxolane (DXL) leads to the formation of 1-trimethylsiloxy-4-iodo-3-oxabutane. In combination with tetrabutyl ammonium triflate this compound can be used as an initiator for the polymerization of vinyl ethers. According to a living polymerization mechanism, the polymers are characterized by controlled molecular weights and narrow molecular weight distributions. The trimethylsiloxy head group originating from the initiation reaction is easily transformed into a primary hydroxyl function by hydrolysis.

Abstract: Two new azo-benzoin initiators were synthesized by the condensation of 4,4′-azo-bis-(4-cyanopentanoic acid chloride) (ACPC) with benzoin (B) and α-methylolbenzoin methyl ether. The initiator structures were confirmed by IR and NMR spectroscopy. The kinetics of the bulk polymerization of styrene initiated by the azo benzoin initiator, obtained from ACPC and B, was investigated and the kinetic parameters evaluated. The initiation of polymerization of styrene by means of azo-benzoin initiators yields polymers with terminal photoactive benzoin groups.

Abstract: Polymerization of cyclic ethers by activated monomer mechanism involves consecutive additions of protonated monomer molecules to the growing macromolecules fitted with hydroxyl groups at their ends. For oxirane itself and symmetrically substituted oxiranes there is only one kind of hydroxyl groups and one, unique way of ring-opening. Unsymmetrically substituted oxiranes provide however two sites of attack and two different hydroxyls, resulting from these ring-openings. Kinetics of polymerization of epichlorohydrin (chloromethyloxirane) has been studied and all four rate constants determined, namely rate constants of the primary and secondary alcoholate chain ends with a protonated monomer, opening in result of the attack on substituted or unsubstituted carbon atom. These rate constants are (in mol−1·1·s−1 at 25°C, in CH2Cl2 solvent): k11 = 0.055, k12 = = 0.41, k22 = 0.135, and k21 = 0.0011 (e.g. k12 is the rate of reaction of the primary alcohol producing the secondary alcohol). Thus, polymerization proceeds almost exclusively on the secondary alcoholate groups, reproducing themselves (k22).

Abstract: A new method for electrochemical polymerization of aniline is presented in which a small amount of p-aminodiphenylamine is added to the polymerization system. In the presence of p-aminodiphenylamine, the rate of polymerization increases greatly, the lower potentials can be applied to generate polyaniline with probably improved quality owing to fewer side reactions, and the more uniform polyaniline films can be prepared.

Abstract: The emulsion polymerization of vinyl acetate using potassium persulfate and cyclohexanone sodium bisulfite as redox pair initiation system was studied. The rate of polymerization, maximum conversion, and the number of polymer particles produced were found to change with redox initiator, monomer and emulsifier concentrations, and temperature variation. The rate of polymerization was found to be dependent on the initiator, the monomer, and the emulsifier concentrations to the 0.88, 0.22, and 0.20 powers, respectively. The K2S2O8–NaHSO3 redox system was found to decrease maximum conversion and doesn't form a stable emulsion. The apparent arrhenius activation energy (Ea) estimated for the polymerization system was 65.6 kJ/mol. The viscosity average molecular weights for some obtained poly(vinyl acetate) were determined.

Abstract: The cationic polymerization of cardanol using borontrifluoridediethyletherate as initiator has been investigated by gel permeation chromatographic techniques. The molecular weight and molecular weight distribution of the polymer at different temperatures and various initiator concentrations were studied, and the polymerization conditions have been optimized as 140°C with an initiator concentration of 1%. The reaction was found to follow first-order kinetics with respect to the monomer. The activation energy and rate constants for the system have also been evaluated. The polymer has been characterized by IR, 1H and 13C-NMR spectra.

Abstract: The present invention relates to coating agents containing A) one or more polymers containing carboxyl groups and having a number-average molecular weight of 500 to 8000 and an acid number of 15 to 200 mg of KOH/g as the essential binder component and B) one or more compounds containing epoxide groups as crosslinking agents, wherein the compound B containing epoxide groups is a copolymer containing epoxide groups, has a number-average molecular weight Mn of 300 to 5000, preferably 500 to 3500, and a heterogeneity (Mw/Mn), measured by gel permea-tion chromatography, of 3, preferably of 2, and has been prepared by continuous bulk polymerization at temperatures between 130 and 350°C and pressures above 1 bar. The invention also relates to processes for the preparation of the coating agent and the use of the coating agents in automobile refinishing.

Abstract: The kinetics of the photoinitiated polymerization of Uvithane 788 was investigated. The Arrhenius plots of ln (initial polymerization rate) versus recriprocal temperature were found to consist of two parts: one below 330 K with an activation energy E a of c. 58 kJ mol −1 and one above 330 K with E a of c. 0 kJ mol −1 . This behaviour is discussed in terms of mobility of the monomer molecules and chain radicals

Abstract: A previously reported method of producing spherical, hydrophilic microparticles by aqueous suspension polymerization is experimentally investigated. The phase separation is the result of a salting-out phenomenon. Characteristics of the salting-out effect between the monomer and suspending phase of aqueous NaCl solution are studied. The size and shape of the produced particles are characterized. It is concluded that the mechanism of polymerization is actually a combination of suspension and solution polymerization, and that the water content in the monomer phase is low enough to produce structurally homogeneous particles.

Abstract: This paper describes a new method of the preparation of block copolymer, in which a mixture of two monomers is subjected to polymerization (simultaneous feeding) by the aid of an initiator. The new method is performed with the polymerization of a family of 2-oxazolines, which proceeds via electrophilic propagating species, cation or covalent bond having electrophilic reactivity. The key to the block copolymer formation with one-shot feeding of monomers is the difference of reactivity of polymerization (nucleophilicity) between the two monomers. First the monomer of higher reactivity is polymerized to completion, and then the monomer of decreased reactivity is polymerized starting from the propagating species of the first polymerization. For the high selectivity of the production of block copolymer, each of two propagations should be of “living mechanism”. Two combinations of monomers, i.e., 2-methyl-2-oxazoline/2-(heptafluoro-n-propyl)-2-oxazoline and 2-phenyl-2-oxazoline/2-(pentafluoroethyl)-2-oxazoline, together with an initiator of methyl tosylate were found to follow the pattern of the new process. Block copolymer of the former monomers' combination was water-soluble, and its aqueous solution showed an excellent value of surface tension.

Abstract: SUMMARY: A kinetic model of the homogeneous anionic polymerization of 1,Cdivinylbenzene (1,4-DVB) in dilute solutions with instantaneous initiation and without cyclization and termination reactions is proposed. The monomer and pendant vinyl group conversions, degrees of polymerization of the primary chains and the crosslinking densities were predicted as a function of the reaction time as well as 1,4-DVB and initiator (butyllithium) concentrations. The previous experimental data concerning the formation of the microgels can be explained using the kinetic mechanism of the polymerization reaction and neglecting cyclization. Calculations indicate that reactive 1,CDVB microgels can be synthesized in the whole concentration range of the initiator.

Abstract: Ethyl α-hydroxymethylacrylate (EHMA) was synthesized from ethyl acrylate and paraformaldehyde, and converted to ethyl α-chloromethylacrylate (ECMA) by reaction with thionyl chloride. ECMA was bulk polymerized at 65°C with α,α′-azobis(isobutyronitrile) (AIBN) to give a homopolymer with a viscosity of 0.084 dL/g. Spontaneous polymerization at ambient temperature surprisingly gave material with an intrinsic viscosity of 0.45 dL/g. Combined size exclusion chromatography-laser light scattering in THF for the former gave Mn = 21,900, Mw = 26,500, and Mz = 34,340 with a dn/dc = 0.079 mL/g. The homopolymer of ECMA was substituted with octadecyl mercaptan in THF using solid NaOH and Aliquat 336 as base and catalyst, respectively. Copolymers of ECMA with styrene were synthesized by free radical polymerization with relatively high conversion. Copolymer compositions were determined using proton NMR and were found to be similar to feed ratios as expected for high conversion products. Both copolymers were reacted with 2-ethyl-2-oxazoline (1:50 mole ratio) in an attempt to graft the oxazoline onto the polymer chain with only limited success. Two potential monomers were synthesized by reacting ECMA with 2-ethyl-2-oxazoline neat and octadecyl mercaptan in CHCl3 using triethylamine as a catalyst. Neither material polymerized under normal radical conditions. Characterization of monomers and polymers involved FTIR and 13C NMR spectroscopy, differential scanning calorimetry, viscosity, and size exclusion chromatography-laser light scattering.

Abstract: Melt processable polyurethaneureas are prepared from a diisocyanate, a macroglycol, a diol chain extender and a diamine chain extender. Water may be included as a reactant, and the polymer may contain an additive such as a radiopaque material. The invention includes a one-pot bulk polymerization method for preparation of the polymers.

Abstract: The aim of the present investigation is the development of a unifying framework for modeling free-radical suspension and bulk vinyl chloride polymerizations. A fairly comprehensive but realistic model is described that has the ability to predict the rate of polymerization as well as the molecular properties of polymer as a function of the process conditions. It is shown that no significant differences exist between the predictions of the present model and those obtained by various well-known two-phase PVC models published before. in addition to the prediction of fractional monomer conversion and rate of polymerization, the new model predicts the anomalous structures observed in commercial PVC, namely, the number of short- and long-chain branches as well as the number of unsaturated terminal double bonds per polymer molecule. Simulation results show that the present model provides realistic predictions of the important molecular properties in agreement with experimental observations reported in th...

Abstract: Azo-benzoin initiators are useful for the synthesis of polymers with photoactive end groups. The kinetics of the bulk polymerization of styrene initiated by 4,4′-azobis(4-cyanopentanoyl)bis(α-methylolbenzoin methyl ether) (ABME) was investigated. On the basis of kinetic parameters, it was found that azo-benzoin initiators exhibit initiator properties similar to that of common azo initiators. A relatively high chain transfer constant of the initiator (C1) may be attributed to the presence of α-methylolbenzoin methyl ether groups in the structure. Azo-Benzoin-Initiatoren sind fur die Herstellung von Polymeren mit photosensitiven Endgruppen geeignet. Diese Arbeit beschreibt die kinetischen Parameter der radikalischen Substanzpolymerisation von Styrol mit 4-4′-Azobis-(4-cyanopentanoyl)-bis-(α-methylolbenzoin-methylether) (ABME). Die Initiatoreigenschaften von ABME ahneln denen gebrauchlicher Azoinitiatoren; die relativ zu diesen hohere Kettenubertragungskonstante von ABME konnte durch die Methoxygruppen im Molekul bedingt sein.

Abstract: The polymerization of e-caprolactone (CL) using triphenyltin acetate has been investigated. Polymers with broad MWD were obtained in almost quantitative yield. After an initial induction period, the polymerization showed zero order kinetics with respect to monomer and nearly first order with respect to catalyst. The mechanism of the propagation reaction is proposed to proceed via an ester alcoholysis, with initiation by traces of water. The zero order kinetics are explained as follows: the tin catalyst is coordinated by the cyclic lactone, monomer addition to the polymer chain in the rate-determining step results in formation of an acyclic ester link, which is no longer a strong donor, and leads to a coordinatively unsaturated tin species.

Abstract: A new computational model for free-radical polymerization reactions was developed. The model algorithm is based on the use of an implicit numerical technique to solve for the coupled monomer and total growing polymer concentration differential equations. Determination of the monomer and total growing polymer concentrations ensures that conservation of mass is maintained without the need to solve the large number of differential equations associated with the growing polymer concentrations for each individual chain length. Acceleration of the numerical calculations was achieved by lumping the growing polymer chains into distinct groups. The proposed numerical scheme generates the monomer conversion and a complete molecular weight distribution (MWD) of the growing and dead polymer chains. The current formulation allows for the incorporation of nonidealities, such as the onset of gelation and chain-length-dependent reaction rate coefficients

Abstract: The kinetic feature of the anionic polymerization of N-PMI was investigated in THF. The polymerization system initiated with lithium tert-butoxide was revealed to be so-called “slow-initiation” system. The rate constant of the initiation reaction, ki, was obtained to be 4.2 × 10−3 (L mol−1 s−1) at −72°C. The apparent rate constants of the propagation reaction, k, at −72°C were individually obtained from each slope of the first-order plots in the later stages of the polymerizations for four different initiator concentrations. Each k is fairly close to that of initiation rate around 10−3. The propagation reaction was concluded to be dominated by ion-pair mechanism from the analysis of the kinetic data and the results of the addition effects of crown ether and common salt.