| Eight kinds of monomers based on monomer bases (i.e., p-styrenesulfonate and vinyl sulfonate) with four different protecting groups (i.e., methyl, isopropyl, butyl and cyclohexyl) were synthesized and copolymerized with methyl methacrylate (MMA) and methacrylic acid (MAA) to give tri-polymers containing sulfonate group, which undergone thermal decomposition and generated sulfonic acid, leading to a great change in affinity, say, from hydrophobic to hydrophilic, upon being heated. This kind of tri-polymers could also be used in combination with a bis-phenyl based cross-linker, i.e., 2,2-bis(4-(2-(vinyloxy)ethoxy)phenyl)propane (BPA-DEVE) and the carboxyl group of the polymer and the vinyl group of the cross-linker could undergo cross-linking reaction under suitable temperature, generating 3-dimension netlike structure. Upon imaging by thermal laser, this netlike structure could be decomposed by the thermo-produced sulphonic acid, releasing large amount of hydrophilic species (i.e., carbonic and sulphonic groups). An even greater gain would be, therefore, achieved in affinity change before and after imaging exposure. Aiming at this goal, a systematic investigation and study was carried out on following aspects. (1) Copolymer system that was compatible with cross-linker. Experimental result showed that the cross-linker was not stable with strong acid (e.g., even with the trace amount of sulphonic acid which would be generated by the copolymer decomposition because of poor thermal stability), undergoing self decomposition and losing activity of cross-linking. A systematic investigation was done on the effect of different protecting groups and sulfonate monomers on thermolysis and thermo-stability properties. DSC, TG and IR data revealed that decomposition temperature and thermal stability of the copolymer mainly relied on the type of protecting groups, almost regardless of the kind of sulfonate unit. Copolymers with protecting groups of methyl or butyl were thermo-stable, showing little lose of weight and no pronounced change in structure after having been kept at 80℃ for 48hrs. Vinyl sulfonate monomers were experimentally found of lower reactivity and couldn't effectively copolymerize with MMA and MAA. Copolymers with methyl protecting group sulfonate unit had high decomposition temperature (more than 300℃) and the corresponding monomer (i.e., butyl p-styrenesulfonate) was, therefore, chosen as the main target for further study and its polymer formed with the other two different monomers was evaluated in thermal imaging.(2) Preparation and thermolysis of the copolymer. The reaction characteristic curve (i.e., f1-F1 curve), the structure and thermolysis property of the copolymer obtained by copolymerizing butyl p-styrenesulfonate, MMA and MAA were systemically studied. DSC data showed that thermo-decomposition temperature of the copolymer remained unchanged at about 213℃, in spite of a great change in the number of sulfonate unit. After baking, polymers containing 52 mol % sulfonate units and 17 mol % MAA units were highly soluble in neutral water, while those containing less than 19 mol % sulfonate units were insoluble in neutral water.(3) Study on dissolving dynamics of polymer film. In order to study dissolving dynamics of polymer film, a homemade appliance which can trace changes in film thickness during dissolution was designed and assembled. The appliance was used to characterize the cross-linking reaction which occurred between the polymer and cross-linker during pre-baking process, the de-cross-linking reaction during the baking process as well as dissolving dynamics of different polymer films. (4) Study on imaging performances of the polymer. Investigation was also done on thermal imaging performances of the polymers by 830nm laser scanning and post treatment. An IR dye which effectively absorbs at 830 nm was added to the polymer. Air-holes and protuberances were found in the laser scanned (exposed) areas and the polymer coating in the exposed areas were completely dissolved away, leaving b...
|
PDF Full Text Request