Lower critical solution temperature behavior of alpha-substituted poly(acrylic acids)s, cyclopolymerization of N-vinylformamido-methylacrylates, and use of the World-Wide Web in polymer science education
A series of α-substituted poly(acrylic acid)s was synthesized and characterized. Their aqueous solution properties were investigated with respect to lower critical solution temperature (LCST) behavior. Poly(α-methoxymethylacrylic acid) was found to have a lower critical solution temperature (LCST) of 46°C, poly(α-methoxyethoxymethylacrylic acid) showed an LCST of 26.5°C and poly(α-methoxyethoxyethoxymethylacrylic acid) showed an LCST of 66°C. The cloud points of the solutions of these polymers were found to be sensitive to pH, and to concentrations of additives such as urea, salts, and surfactants. Because of low molecular weight due to chain transfer, high molecular weight analogs of the ether-linked polymers were synthesized in which ester linkages joined the oligo-oxyethylene segment to the acrylate moiety. Poly(α-methoxyethoxyacetoxymethylacrylic acid) was the only one of this series to give an LCST with a value of 52.5°C. Copolymers of t -butyl α-methoxymethylacrylate (tBMMA) with α-(1H,1H- perfluorooctyloxymethyl)acrylic acid (PFOMA) were synthesized, deprotected and their lower critical solution temperatures (LCSTs) evaluated. At PFOMA feed ratios of 0.25 mol % or less, no observable change in the LCST was observed, while at PFOMA feed ratios of above 0.25 mol % to 1.125 mol %, a large linear decrease in the LCST was observed with increasing fluorocarbon content. t -Butyl α-(N -vinylformamidomethyl)acrylate (tBVFA) and ethyl α-(N-vinylformamidomethyl)acrylate (EVFA) were synthesized from t -butyl α-bromomethylacrylate and ethyl α-chloromethylacrylate, respectively. tBVFA was found to cyclopolymerize at 120°C in DMF, DMSO, and 1,2-dichlorobenzene at solvent:monomer ratios of 10:1 vol:wt. Molecular weights for poly(tBVFA) ranged from 10,000 to 13,000 as estimated by size-exclusion chromatography. At lower solvent monomer ratio (1:1), and at lower temperature (71°C), crosslinking occurred. EVFA was found to cyclopolymerize, but only in DMF at 122°C and at a 10:1 solvent:monomer ratio. A multimedia educational program called The Macrogalleria dealing with polymer science was created and distributed by the world wide web and on cd-rom. The site is made in the form of a virtual shopping mall in which each store is a lesson on some aspect of polymer science. The lessons are written in informal language to make the material more accessible. Also, the lessons are connected by hypertext links in a nonlinear fashion to allow students to create their own pathways through the material. The Macrogalleria has been very successful, being used by educational institutions to incorporate polymer science into the undergraduate chemistry curriculum, and by many industrial users as well. It has received numerous awards as well.