Showing papers on "Ionic polymerization published in 1985"

Morphology of latex particles formed by poly(methyl methacrylate)-seeded emulsion polymerization of styrene

Abstract: Poly(methyl methacrylate)–polystyrene composite particle latexes were prepared by poly(methyl methacrylate)-seeded emulsion polymerization of styrene employing batch, swelling-batch, and semibatch methods. The changes in particle morphology taking place during the polymerization reaction were followed by electron microscopy. Anchoring effect exerted by ionic terminal groups introduced by ionic initiator was found to be the main factor in controlling the particle morphology. The polymer particles obtained by oil-soluble hydrophobic initiators such as azobisisobutyronitrile and 4,4′-azobis-(4-cyanovaleric acid) gave the inverted core-shell morphology. Water-soluble hydrophilic initiator, K2S2O8, also gave the inverted core-shell morphology. However, in this case the occurrence of the halfmoonlike, the sandwichlike, and the core-shell morphologies were also observed depending upon the polymerization conditions. The distribution of terminal SO groups on the surface area of polystyrene particles could be controlled by initiator concentration and polymerization temperature. Viscosity of polymerization loci dictated the movement of polymer molecules, thus causing the unevenness of particle shape and phase separation at high viscosity state. Viscosity was controlled by the styrene/poly(methyl methacrylate) ratio, the addition of a chain transfer agent or a solvent which is common to polystyrene and poly(methyl methacrylate).

Polymerization of 1-(trimethylsilyl)-1-propyne by halides of niobium(V) and tantalum(V) and polymer properties

Abstract: Polymerisation dans le toluene a 80°C. Influence du solvant et de la temperature. Conformation twist. Polymere blanc amorphe, soluble, stable a l'air, dielectrique solide non paramagnetique

Immortal polymerization. Polymerization of epoxide catalysed by an aluminium porphyrin-alcohol system

Abstract: Ring-opening polymerization of epoxide catalysed by a (tetraphenylporphinato)aluminium chloride-alcohol system affords a polyether having a controlled molecular weight of narrow distribution with the number of the polymer molecules exceeding the number of aluminium porphyrin molecules; this is due to exchange between the alcohol and the (porphinato)aluminium alkoxide, which is the active species, resulting in the ‘immortal’ nature of the polymerization.

Polymerization of monomers containing functional groups protected by trialkylsilyl groups, 4. Studies on anionic living polymerization of 4‐(tert‐butyldimethylsilyloxy)styrene

Abstract: Anionic polymerization of 4-(tert-butyldimethylsilyloxy)styrene (2) was investigated under high vacuum conditions (≈ 10−6 mbar). 2 was readily polymerized by lithium naphthalide to form a “living polymer” at −78°C. By subsequent acid hydrolysis of the resulting polymer, a linear, nearly monodisperse polymer of 4-vinylphenol of known molecular weight was obtained. Block copolymers of 2 with α-methylstyrene were also prepared by means of this living system.

Synthesis of a propene—methyl methacrylate diblock copolymer via “living” coordination polymerization

Abstract: A new diblock copolymer of propene and methyl methacrylate (MMA) was prepared by adding MMA during the living coordination polymerization of propene together with the soluble catalyst V(acac)3/Al(C2H5)2Cl at −78°C and subsequently by raising the polymerization temperature up to 25°C. The homopolymerization of MMA with this catalyst exhibits the characteristics of a living polymerization at the initial stage of polymerization. From the copolymerization of MMA with styrene, it was concluded that the polymerization of MMA occurs via a radical intermediate. It is suggested that a propene-MMA diblock copolymer is formed via the transformation of a living polypropylene end to a radical end.

Cationic ring-opening polymerization

Abstract: Advances in the major areas of the cationic ring-opening polymerizations are discussed. In the first part synthesis of new polymers is reviewed; this includes mainly novel block and graft copolymers based on the di- and multicationically ended living polyacetals and polyethers (polyTHF). Recent data on thermodynamics of nonideal systems, giving dependence of [M]e on [M]o, are summarized with special emphasize of the differences between monomers due to variation of their nucleophilicities. Discussion of kinetics and mechanisms of polymerization of cyclic acetals and ethers is focused on the macroring formation and reactivities of active centers. The reactivity of covalent and various ionic growing species are compared in the polymerization of cyclic ethers (THF and oxepane) and oxazolines. Reasons for much lower reactivity of covalent than ionic species and reasons for similar reactivities of macroion-pairs and macroions are presented. It is shown, that the kinetically controlled proportions of macrorings in the polymerization of these and other heterocyclic monomers depend on the structure of the end-groups, formed upon initiation. Initiation with acids, giving H-X∼ (where X=heteroatom) end-groups, leads to the kinetically enhanced proportion of macrorings. This is particularly important for the low degrees of polymerization.

Polymerization of olefins through heterogeneous catalysis. II. Kinetics of gas phase propylene polymerization with Ziegler–Natta catalysts

Abstract: Propylene was polymerized in gas phase over a (Stauffer Type AA) Catalyst with AlEt2Cl cocatalyst both with and without H2 present. The effects of polymerization temperature, monomer concentration, catalyst composition, and hydrogen were investigated. The experiments were carried out at operating conditions approaching industrial practice.

Polylactones: 5. Polymerization of L,L-lactide by means of magnesium salts

Abstract: Polymerisation en masse a 120, 150 (principalement) et 180°C. Le rendement maximum (96%) est obtenu avec l'oxyde de magnesium

Polymeric or polymerisable aromatic-aliphatic ketones suitable for use as polymerisation photoinitiators

Abstract: A new class of polymeric or polymerizable aromatic-aliphatic ketones, the preferred of which are: 2-hydroxy-2-methyl(4-vinylpropiophenone), 2-hydroxy-2-methyl-p(1-methylvinyl)propiophenone, p-vinylbenzoylcyclohexanol, p-(1-methylvinyl)benzoyl-cyclohexanol and their oligomerization and polymerization products, they being suitable for use as photoinitiators for the photopolymerization of ethylenically unsaturated monomers and prepolymers. Said ketones are produced by subjecting an aromatic substrate, preferably a monomer or oligomer of styrene type, to the following reaction cycle: polymerization - acylation - alphachlorination - nucleophilic substitution with the formation of epoxyether - hydrolysis of the epoxyether; or to other reactions as modifications or alternatives to this cycle. The ketones according to the present invention have high efficiency as photoinitiators both with regard to the useful concentration to be used and with regard to the polymerization rate.

Polymerization of p‐cresyl glycidyl ether catalyzed by imidazoles I. The influence of the imidazole concentration, the reaction temperature, and the presence of isopropanol on the polymerization

Abstract: The polymerization of p-cresyl glycidyl ether catalyzed by imidazoles has been investigated as a model reaction for the polymerization of technical epoxy resins. The dependence of oligomer yield on time, temperature, and imidazole concentration, the distribution of the polymerization degrees, and the influence of isopropanol have been studied. The reaction rate and the average degree of polymerization are affected by the presence or absence of a secondary nitrogen on the imidazole, i.e., different results are obtained when 2-ethyl, 4-methyl imidazole (EMI) or 1-methyl imidazole (1-MIA) are used. 1-MIA seems to be “precursor” of the catalyst rather than a catalyst by itself. The comparisons of CGE polymerizations catalyzed by 1-MIA in the absence and presence of isopropanol show only quantitative differences: The polymerization in the presence of isopropanol is faster, and the average degree of polymerization is shifted to higher values. The activation energies of CGE polymerizations catalyzed by different imidazoles have been determined.

A kinetic study of the activated anionic polymerization of ε-caprolactam

Abstract: The diversities existing among published kinetic studies on activated anionic polymerization of e-caprolactam are closely examined. A kinetic model derived from a regular, linear reversible reaction mechanism is employed to explain the experimentally observed autocatalytic character of the polymerization system and to examine the dependence of the apparent activation energy on the experimental method. Several existing kinetic models tested with our experimental data show that the autocatalytic type rate equation best describes the polymerization process.

Effect of organometallic cocatalysts on the polymerization of 1-phenyl-1-propyne by tantalum pentachloride (TaCl5) and niobium pentachloride (NbCl5)

Abstract: Il y a degradation lorsque tout le monomere a disparu; mais les chlorures du titre accelerent la polymerisation et inhibent la degradation

Syntheses of 2-phenyl-3-vinyloxirane derivatives that undergo radical ring-opening polymerization

Abstract: 2-Phenyl-3-vinyloxirane derivatives that undergo radical ring-opening polymerization were prepared from allyl bromide and corresponding aldehydes. The difunctional monomers containing vinyloxirane structure were also synthesized from dialdehydes such as isophthalaldehyde and terephthalaldehyde. The obtained monomers undertook the radical isomeric polymerization to obtain the corresponding polymers.

Cationic polymerization of 1,3-dioxolane and 1,3-dioxepane. Application to graft and block copolymer synthesis

Abstract: The cationic polymerization of 1,3-dioxolane and 1,3-dioxepane has been investigated to prepare "living" polymers and then to use them for copolymerization. Carbenium hexafluoroantimonate salts tha...

Polymerization of tert-alkylacetylenes by Mo- and W-based catalysts†

Abstract: Polymerization of three tert-alkylacetylenes (3,3-dimethyl-1-pentyne, 3,3-dimethyl-1-nonyne, 1-adamantylacetylene) by Mo- and W-based catalysts provided new polymers in virtually quantitative yields. In contrast, Ziegler catalysts did not polymerize these monomers. Every polymer had a form of white solid, and had alternating double bonds along the main chain. Though some of poly(3,3-dimethyl-1-pentyne)s contained a toluene-insoluble fraction, the polymer was totally soluble when proper polymerization conditions were chosen. The molecular weights of soluble fractions were as high as 3 × 105. Poly(3,3-dimethyl-1-nonyne) was also partly insoluble in toluene, and the quantity of soluble fraction was less than that of poly(3,3-dimethyl-1-pentyne). The geometric structure of these two polymers could be controlled by the choice of suitable polymerization conditions. Poly(1-adamantylacetylene) was insoluble in any organic solvents. Copolymerization of 1-adamantylacetylene with suitable comonomers afforded soluble copolymers.

Group Transfer Polymerization Synthesis and Group Transfer Polymerization and Copolymerization of p-Vinylbenzyl Methacrylate

Abstract: Recently, a new addition polymerization technique known as group transfer polymerization (GTP) was developed ( I -7 ) . I t uses s i l y l ketene acetals and other organosilicon compounds as in i t i a to rs , and either nucleophil ic (eg. HF2-, CN-, F-, N2-) (1,2) or e lectrophi l ic (Lewis acids) (3) catalysts to polymerize polar monomers such as methacrylates, acrylates, acrylamides, etc. through a l iv ing mechanism. Therefore, i t has the important advantages associated with l iv ing polymers, including the capabi l i ty to give polymers with narrow molecular weight d is t r ibut ion, the a b i l i t y to control the molecular weight by the rat io of monomer to i n i t i a t o r , and the a b i l i t y to synthesize telechelics (4,5) and block copolymers (7). Also, i t proceeds rapidly at room temperature and i t can be used to polymerize acrylates through a l iv ing mechanism, both in contrast to anionic polymerization which can only be used to polymerize methacrylates at low temperature by a l iv ing mechanism (8,9). Despite the unique chemistry and advantages of GTP, l i t t l e has been done to exploi t i t s potential of polymerizing unusual monomers (2,7,10). One of the most important potential applications of GTP would be the polymerization of polar double bonds to the exclusion of nonpolar double bonds. Of par t icu lar interest is the e lect rophi l ic catalyzed GTP of 2-methacryloyloxyethyl acrylate, which gives a polymer containing pendant methacryloyl groups (7). We are interested in functional polymers containing pendant or terminal styrene groups, since they represent a novel class of thermally reactive oligomers (11-14). The goal of this paper is to present the synthesis and group transfer polymerization and copolymerization of the bifunctional monomer p-vinylbenzyl methacrylate. This is the f i r s t example of a monomer polymerized select ively at a polar

Advances in the synthesis and polymerization of metal-containing monomers

Abstract: Polymerization and copolymerization of metal-containing monomers (MCM) is a unique method of synthesizing metal-containing polymers wherein practically all functional groups are bound to the metal.

Activated anionic polymerization of lactams

Abstract: Improved activators for anionic polymerization of lactams are biuret-containing polyisocyanates based on non-aromatic diisocyanates.

Ring-opening polymerization of 2-methylene-4-phenyl-1,3-dioxolane

Abstract: Photochemical and radical polymerization of 2-methylene-4-phenyl-1,3-dioxolane (1) were carried out leading to the same polyester 2. By radical copolymerization of 1 with methyl methacrylate using various mole ratios of the monomers, the corresponding copolymers with various contents of ester groups in the backbone were obtained.

Ring‐opening polymerization with kinetically controlled enhancement of macrocyclic oligomers or linear macromolecules

Abstract: The equilibrium and the kinetics of the ring-opening polymerization accompanied with backbiting and end-to-end ring closure are analyzed using computer simulation. The influence of monomer ring strain and competition between back-biting and end-biting on the overall kinetic process is evaluated. The results of calculations are compared with examples from the ionic ring opening polymerization of heterocyclic monomers. It is established that in the polymerization of nonstrained monomers fast end-biting manifests itself by an induction period. In the absence of end-biting the polymerization of strained monomers yields a system in which the polymer concentration is temporarily higher than at equilibrium (kinetic enhancement in polymer). On the other hand, very fast end-biting, hindered only in the case of the monomeric species by the ring strain, results in concentrations of the macrocyclics which are transitorily higher than the corresponding equilibrium concentrations (kinetic enhancement of macrocycles). The polymer synthesis with kinetically controlled concentration of cyclics is indicated.

Polymerization of oriented monomers. VIII. Polymerization of allyl and diallyl vesicle‐forming quaternary ammonium salts

Abstract: The synthesis of two novel allyl and diallyl vesicle-forming quaternary ammonium salts is reported. The topochemical polymerization of these monomeric vesicles to their polymerized counterparts was performed by γ-ray irradiation and the observed differentiation in polymerization rates of allyl and diallyl monomers was attributed to different polymerization mechanisms. It was further established that only polymerized vesicles which result from diallyl monomer retain the structure of the monomeric vesicles and exhibit simultaneously higher stability.

Haloaldehydep polymers: 28. Synthesis and polymerization of fluorochlorobromoacetaldehyde

Abstract: Synthese du monomere a partir du trifluorochloroethylene. Polymerisation en presence d'acide sulfurique

Macromonomers as polymeric intermediates. Synthesis and applications

Abstract: The methods developed for the synthesis of macromolecular monomers (macromonomers) are reviewed, with emphasis on those based on ionic “living” polymerization techniques which give access to well-defined species of low polydispersity. The ability of the terminal unsaturation to undergo free radical polymerization (or copolymerization with a vinylic or acrylic monomer) is considered next. Homopolymacromonomers are characterized by an unusually large segment density within the polymer coil. The chief interest of macromonomers is the easy access to graft copolymers they can provide, especially for amphiphilic species constituted of a hydrophobic backbone carrying hydrophilic grafts. Further applications of macromonomers can also be envisioned.

Free radical initiated polymerization of polymerizable ethylenically unsaturated monomer component in the presence of hydrogen peroxide

Abstract: A method of preparing a free radical initiated addition polymer in the presence of hydrogen peroxide solution is disclosed. The hydrogen peroxide solution is added incrementally to the reaction mixture during the course of the polymerization with water and low boiling organic solvents being continuously removed from the reaction mixture. The invention enables the polymerization to occur at high temperatures which is conducive to the preparation of low molecular weight polymers.