Multi-detector thermal field-flow fractionation (ThFFF) as a characterization technique for complex polymer self-assemblies

Muza, Upenyu Lucky (2017-03)

Thesis (MSc)--Stellenbosch University, 2017.


ENGLISH ABSTRACT: Amphiphilic block copolymer micelles have found a niche in pharmaceutical, electronics, environmental, cosmetics and hygiene industries. These micelles, whether in the pure or mixed micelle form, often exist as multiple morphologies (spherical, cylindrical, worm or vesicular) in equilibrium with each other. However none of the current techniques can successfully separate and characterize these multiple morphologies with regards to size, molar mass, chemical composition and their respective distributions, in a single measurement. Thermal field-flow fractionation (ThFFF) is shown to be capable of separating and characterizing pure micelles prepared from two types of polystyrene - polyethylene oxide block copolymers (PS-PEO), of different PS block sizes but similar PEO block sizes. Moreover, multiple micelle morphologies induced by the addition of 1 mM LiBr, as well as multiple mixed micelles prepared from various binary blending protocols of the two PS-b-PEO copolymers were successfully characterized. In addition, ThFFF is shown to be capable of monitoring the dynamics of formation of the mixed micelles.

AFRIKAANSE OPSOMMING: Amfifiliese blok ko-polimere het n nismark in verskeie farmaseutiese, elektroniese, kosmetiese, higiëniese asook in die omgewings industrië gevind. Miselles, suiwer of gemeng, bestaan gewoonlik in ewewig met verskeie morfologië soos bv. silindries, spheries of wurm. Tans is daar geen enkele analitiese tegniek wat hierdie verskeie morfologië kan skei in terme van groote, molekulêre massa en chemiese samestelling, of hul verspreidings, in n enkele analiese nie. Dit word gewys dat termiese veldvloeifraksionering (ThFFF) miselles, wat bestaan uit polistireen-blok-poli(etileenoksied) (PS-PEO) ko-polimere met verskeie PS blok lengtes maar selfde PEO blok lengtes, kan skei. Dit word ook gewys dat verkseie morfologië word gevorm in 1 milimolar litium bromide en dat hierdie morfologië, asook gemengde miselles wat berei is deur verskillende tegnieke, deur ThFFF gekarakteriseer kan word. Dit word ook gewys dat ThFFF gebruik kan word om die vormings dynamika van miselles te monitor.

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