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Synthesis of specifically functionalized polymers and their adsorption at the solid-solution interface
Abstract
The synthesis and adsorption characteristics of specifically functionalized block copolymers have been investigated. Specifically functionalized polymers are block copolymers of controlled MW, MWD, block size and block placement, and meet the requirement that one of the blocks interact strongly with a given surface whereas the other one does not. Synthetic procedures involved living anionic polymerization of various monomers, allowing preparation of narrow-dispersity block copolymers of specific molecular weight, overall composition, block lengths and (in one system used) block placement. The location (along the chain) of the surface attachment could be controlled through appropriate block sequences. The grafting of polystyrene chains to the surface of poly(chlorotrifluoroethylene) film was accomplished by reaction of the surface with three living polymer anions: polystyryl lithium, butadiene endcapped polystyryl lithium and ethylenesulfide endcapped polystyryl lithium. The effects of solvent, reaction temperature, reaction time and anion concentration of the grafted layer were studied by XPS, ATR-IR, gravimetrics and contact angle. The synthesis of styrene/propylenesulfide block copolymers was studied in some detail and was found to result in polymeric dimers caused by disulfide formation. These disulfide linkages were cleaved by reaction with dithiothreitol (DTT). Endcapping with ethyl bromide stabilized the polymers against disulfide formation and degradation of the polypropylenesulfide block. These polymers were adsorbed onto gold surfaces (from THF and cyclohexane) and analyzed by XPS, contact angle, and photomodulated external reflectance IR spectroscopy. The amount adsorbed was found to decrease with increasing size of the polypropylenesulfide (sticky) block. The largest body of work presented discusses the synthesis of SF polymers with controlled placement of SF blocks at desired locations along the chain. This work focussed on the specific functionalization of the styrene blocks in styrene/tert-butyl styrene block copolymers. The various sulfonation reactions investigated gave poor results. Reaction with DEOM/SnCl$\sb4$ was found to be very selective, controllable and allowed introduction of hydroxydiethyl malonate SF at various positions along the chain. The adsorption of these (diblock and triblock) polymers to various silica surfaces was investigated. The data are qualitatively compared with theoretical predictions by both Marques and Evers.
Subject Area
Polymer chemistry
Recommended Citation
Kolb, Brant Ulrick, "Synthesis of specifically functionalized polymers and their adsorption at the solid-solution interface" (1993). Doctoral Dissertations Available from Proquest. AAI9316683.
https://scholarworks.umass.edu/dissertations/AAI9316683