The effect of iodo alkyl chain transfer agents on the seeded emulsion homo- and co-polimerisation of styrene and butyl acrylate

Beyers, Cornelis Petrus (1999)

Thesis (MSc) -- Stellenbosch University, 1999.

Thesis

ENGLISH ABSTRACT: A free-radical polymerisation process, which has characteristics of a living polymerisation system, as it is capable of producing polymers of pre-determined molecular masses with a narrow molecular mass distribution, is discussed. It is also possible to make blockcopolymers by adding adding different monomers. The basic objective was to describe, discuss and explain the results of the effects of alkyl iodides as chain transfer agents on the seeded emulsion homo- and co-polymerisation of styrene and butyl acrylate. lodoacetonitrile and 1-phenylethyliodide were used as alkyliodides, acting as degenerative chain transfer agents. First, the effects of these alkyl iodides as chain transfer agents on the molecular mass, molecular mass distribution, glass transition temperature, conversion and particle size for the seeded emulsion polymerisation of styrene were studied. Second, the effects of alkyl iodides as chain transfer agents on the kinetics of radical emulsion polymerisation, especially the average amount of radicals per latex particle, were investigated. Third, the possibility of producing block-copolymers by emulsion polymerisation, using alkyl iodides as chain transfer agents, was investigated. To the best of the author's knowledge, results of work carried out in this study offer the first proof that the "living"/controlled radical polymerisation of styrene, with alkyl iodides as chain transfer agents, can be successfully carried out in emulsion. Addition of different alkyl iodides as chain transfer agents, in different concentrations, led to marked changes in the molecular mass, molecular mass distribution, glass transition temperature, conversion and particle size for the seeded emulsion polymerisation of styrene. The molecular masses of the polystyrene that was produced ranged from 156 to 663 577 while the average molecular mass distribution was below 2. Addition of these alkyl iodides to a seeded styrene polymerisation under zero-one conditions led to an average number of free radicals per latex particle that was greater than 1. A styrene seed latex with functional iodine end-groups was created and was successfully co-polymerised with butyl acrylate to produce a perfect styrene-butyl acrylate block-copolymer. This work has industrial importance as it allows the molecular mass, molecular mass distribution and particle size of polymers to be controlled. These factors are directly related to their micro- and macrostructure of polymers.

AFRIKAANSE OPSOMMING: Die vrye-radikaal polimerisasie proses wat die eienskappe van In lewendige polimerisasie sisteem toon, omdat dit moontlik is om 'n polimeer met voorafbepaalde molekulêre massas en 'n baie klein molekulêre massa verspreiding te berei, is bespreek. Dit is ook moontlik om, deur die byvoeging van 'n tweede monomeer, 'n blok ko-polimere te maak. Die doel was om die effekte wat alkieljodiede as ketlingoordragagente op die "seed" homo- en ko-polimerisasie van stireen en butiel akrielaat gehad het te beskryf en te verklaar. Jodoasetonitriel en 1-fenieletieljodied is gebruik as degeneratiewe kettingoordragagente. Eerstens is die uitwerking van hierdie alkieljodiede as kettingoordragagente op die molekulere massa, molekulere massa verspreiding, glas oorgang temperatuur, opbrengs en partikelgrote van die "seed" emulsie polimerisasie van stireen bestudeer. Tweedens is na die uitwerking van alkiekjodiede op die kinetika van In emulsie radikaal polimerisasie gekyk met spesifieke 1<lem op die gemiddelde aantal radikale per emulsie partikel. Derdens is die moontlikheid om blok ko-polimere te berei ondersoek. Na die beste van die outeur se wete is die resultate van hierdie studie die eerste bewys dat die "Iewendige"/gekontroleerde radikaal polimerisasie van stireen met alkieljodiede as ketlingoordragagente suksesvol in emulsie polimerisasie uitgevoer kan word. Die byvoeging van verskillende alkieljodiede, in verskillende konsentrasies, het aanleiding gegee tot opmerklike veranderinge in die molekulere massa, molekulere massa verspreiding, glas oorgang temperatuur, opbrengs en partikelgrote van die "seed" emulsie polimerisasie van stireen. Die molekulere massas van die bereide polistiereen het gewissel tussen 156 en 663 577 en die gemiddelde molekulere massa verspreiding was onder 2. Byvoeging van die alkieljodiede by die "seed" polimerisasie van stireen onder zero-een toestande het In gemiddelde aantal radikale per emulsie partikel van bo 1 gelewer. In Funksionele "seed" emulsie met jodium eindgroepe was geproduseer na 'n suksesvolle ko-polimerisasie met butiel akrielaat en 'n perfekte stireen-butiel akrilaat kopolimeer is verkry. Hierdie werk het industriele belang aangesien dit die beheer van molekulere massa, molekulere massa verspreiding en partikelgrote moontlik maak wat 'n direkte effek het op die mikro- en makro strukture van die polimeer.

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