Yasuhisa Tsukahara

Pyrolysis-gas chromatography for end group analysis of polystyrene macromonomers using stepwise pyrolysis combined with on-line methylation

Abstract The end group functionalities of polystyrene macromonomers with methacryloyl (ML) end groups were determined by stepwise pyrolysis-gas chromatography (PyGC) at different temperatures, using a two stage pyrolyser consisting of two independent furnaces, combined with an on-line methylation technique. The macromonomer sample in THF solution was mixed with tetramethylammonium hydroxide in methanol solution, as the methylation reagent, in a sample cup; this was introduced into the first furnace (250°C) of the pyrolyser attached to a gas chromatograph to decompose selectively the ML end group moieties in the macromonomer to methyl methacrylate (MMA). After GC analysis of the formed MMA, the sample cup was dropped down into the second furnace (650°C) to pyrolyse the residual polystyrene main chain thoroughly. The concentration of the ML end groups was determined by comparing the peak intensity of MMA observed in the former pyrogram with those of the characteristic products formed from the polystyrene main chain in the latter pyrogram. The end group functionalities of several macromonomer samples calculated from the concentrations of the end groups, determined by PyGC, were in fairly good agreement with those determined by 1 H NMR, and with those calculated from the data of the maximum conversion of the macromonomers.

Synthesis and Application of Tailored Graft Copolymers from Polystyrene Macromonomer

Abstract Comb graft copolymers prepared by macromonomer technique has become applicable for permanent modification of polymer surfaces. In this paper the association and adsorption behavior in solution of the well designed graft copolymer prepared from polystyrene macromonomer and various hydrophilic comonomer was studied and the mechanism of surface accumulation of hydrophilic segment was clarified by surface analysis of polystyrene containing the graft copolymers. Wetting of modified polymer surfaces and the permeability of gases through the film was also discussed.

Surface Modification of Polymethyl Methacrylate by Graft Copolymers

SummaryGraft copolymers composed of poly(methyl methacrylate) branches and different backbones of poly(fluoroalkyl acrylate(FA)-co-methyl methacrylate(MMA)), poly (hydroxyethyl methacrylate(HEMA)-co-MMA), and poly(FA-co-HEMA) were prepared by macromonomer technique to study their application as a surface modifier for PMMA films. Contact angle of water droplet on PMMA film specimens containing various amounts of these graft copolymers cast on glass slides from THF solution was found to change considerably with the graft copolymer concentration, depending on their backbone component. And there was considerable difference in contact angle between air and glass side of the film surfaces. These results were considered in terms of the surface accumulation of graft copolymers during the solvent evaporation.

Control of Polymer Surface Structure by Tailored Graft Copolymers

Surface properties of polymers are known to be of considerable importance in applications such as coatings, adhesives, films, fibers and moldings. Hydrophilic modification of nonpolar polymers is useful to improve adhesion, wetting, coating and antistatic properties. Hydrophobic modification of polar polymers is useful to improve water and oil repellency, and frictional properties. Among many surface modification techniques including chemical, UV and plasma treatments, surface accumulation of functional segments by using tailored graft copolymers appears to be most promising to obtain a controlled surface structure for any particular application. The use of surface active agents as integral surface treatments has been investigated by Zisman and coworkers1,2, who have pointed to the suitability of fluorinated surfactants and polysiloxane surfactants. Ten years ago, Gaines3 and Owen4 have independently shown that dimethylsiloxane block copolymers do concentrate at the surface when they are added, in low concentrations, during fabrication of solid polymers. These blockcopolymers appear to be particularly suitable additives for practical application because they are effective at very low levels, resist removal from the surface by rinsing and are useful for permanent surface modification.

Synthesis and application of fluorine containing graftcopolymers

SummaryWell-defined graftcopolymers were prepared by radical copolymerization of methyl methacrylate macromonomer with perfluoroalkyl acrylate. Contact angle of the solvent cast films of poly(methyl methacrylate) containing various amount of the graftcopolymer was measured against water droplet. Addition of 0.2 wt% of the graftcopolymer was sufficient to improve the polymer films to water repellent surfaces, while 10 wt% was necessary to modify the polymer surfaces to the same level of water repellency.