Thesis (MSc)--Stellenbosch University, 2001 / ENGLISH ABSTRACT: The effect of various organic reducing agents, in the. form of monosaccharide reducing sugars, on the
rate of atom transfer radical polymerization (ATRP) of n-butyl methacrylate and methyl methacrylate is
reported in this study. The addition of the reducing sugars has a positive effect on the rate of ATRP. Up
to 100% increase in the rate of polymerization was recorded, in some cases. These organic reducing
agents have little effect on the molecular weight and molecular weight distribution of the polyin-butyl
methacrylate) and polydispersity indexes remain well below 1.2. The molecular weight of the
poly(methyl methacrylate), when glucose and galactose are added to the reaction mixture, compares
well with the theoretical expected values.
An explanation for these observations is the ability of the reducing sugars to reduce part of the Cu(II)
species, that serves to deactivate the growing radicals, to Cu(I), thereby ensuring a shift in the
equilibrium between active and dormant chains in the direction of the former and a resulting increase in
the rate of polymerization.
uvNIS spectroscopy and cyclic voltammetry were used to investigate the mechanism behind the
polymerization rate enhancement. / AFRIKAANSE OPSOMMING: In hierdie studie word die effek van verskeie organiese reduseermiddels, in die vorm van monosakkaried
reduserende suikers, op die tempo van polimerisasie van ATRP gerapporteer. Hierdie reduserende
suikers het 'n positiewe effek op die polimerisasie tempo. In sommige gevalle word 'n toename van
100% in die polimerisasie tempo waargeneem. Die organiese reduseermiddels het 'n minimale effek op
die molekulere massa en molekulere massa verspreiding (in meeste gevalle minder as 1.2) van die
poly(n-butiel metakrielaat). In die geval van die poly(metiel metakrielaat), wanneer glukose en
galaktose by die reaksie mengsel gevoeg word, stem die molekulere massas goed ooreen met die
teoreties voorspelde molekulere massas.
Die waargenome toename in die polimerisasie tempo kan toegeskryf word aan die vermoe van die
reduserende suikers om die Cu(II), wat dien om die groeiende radikale te deaktiveer, gedeeltelik te
reduseer na Cu(l). Hierdeur word verseker dat die ewewig tussen die aktiewe en dormante kettings in
die rigting van die eersgenoemde verskuif word, wat dus aanleiding gee tot 'n toename in die
polimerisasie tempo.
Ultraviolet spektroskopie en sikliese voltammetrie is ook gebruik om lig te werp op die meganisme agter
die toename in die tempo van polimerisasie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52519 |
| Date | 12 1900 |
| Creators | De Vries, Andrew Robert |
| Contributors | Kluraperman, B., Sanderson, R. D., De Wet-Roos, D., Stellenbosch University. Faculty of Science. Dept. of Chemistry & Polymer Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 72 p. : ill. |
| Rights | Stellenbosch University |
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