The crystallization of poly(vinylcyclohexane)-b-poly(ethylene)-b-poly(vinylcyclohexane)(PVCH-PE-PVCH) triblock copolymer/chloroform solution was investigated. The solvent of the solution system was evaporated at vario...The crystallization of poly(vinylcyclohexane)-b-poly(ethylene)-b-poly(vinylcyclohexane)(PVCH-PE-PVCH) triblock copolymer/chloroform solution was investigated. The solvent of the solution system was evaporated at various temperatures. It was found that the crystallinity was decreased with increasing the solvent evaporating temperature. This indicated that the crystallinity depends on the crystallization time because the higher the evaporating temperature, the faster the speed of the solvent evaporating is. However, the melting temperature(T_m) of the block copolymer was found to depend on the competition between the crystallization and the microphase separation. When the evaporating temperature is lower(below 333 K), i.e. the speed of the solvent-evaporating is slow, the PE block crystallized freely and the T_m increased with increasing the solvent evaporating temperature, implying that the T_m only depends on the crystalline temperature. On the other hand, with the increasing temperature up to above 343 K for solvent evaporating, two melting peaks at 356 and 377 K were observed for the crystallization of PVCH-PE-PVCH in the solution. It resulted in that the crystallization and the microphase separation of the block copolymer occurred simultaneously. And the confined and unconfined crystallization coexisted for the samples. The competition of the crystallization and the microphase separation can be controlled through changing the solvent evaporating speed.展开更多
The melting and recrystallization behaviour of poly（vinylcyclohexane）-b-poly（ethylene）-b-poly（vinylcyclohexane）（PVCH-PE-PVCH） triblock copolymer in supercritical carbon dioxide(CO2) was investigated by（using...The melting and recrystallization behaviour of poly（vinylcyclohexane）-b-poly（ethylene）-b-poly（vinylcyclohexane）（PVCH-PE-PVCH） triblock copolymer in supercritical carbon dioxide(CO2) was investigated by（using） of DSC.The effect of the rate of the depressurization of CO2 on the crystallization of the samples was also examined.It is found that there are three melting peaks on each DSC curve of the samples treated in supericritical CO2 at the temperature above tm of the untreated PVCH-PE-PVCH.They corresponded to the 'hard' confined crystallization of PE blocks homogeneous nucleation,the 'soft' confined crystallization of PE blocks homogeneous nucleation and the self-seeding nucleation free crystallization of PE blocks respectively.Furthermore,these three kinds of crystallization could be controlled by changing the competition between the crystallization of PE block and the vitrifaction of PVCH block in the samples,which depended on the rate of the depressurization of CO2.展开更多
文摘The crystallization of poly(vinylcyclohexane)-b-poly(ethylene)-b-poly(vinylcyclohexane)(PVCH-PE-PVCH) triblock copolymer/chloroform solution was investigated. The solvent of the solution system was evaporated at various temperatures. It was found that the crystallinity was decreased with increasing the solvent evaporating temperature. This indicated that the crystallinity depends on the crystallization time because the higher the evaporating temperature, the faster the speed of the solvent evaporating is. However, the melting temperature(T_m) of the block copolymer was found to depend on the competition between the crystallization and the microphase separation. When the evaporating temperature is lower(below 333 K), i.e. the speed of the solvent-evaporating is slow, the PE block crystallized freely and the T_m increased with increasing the solvent evaporating temperature, implying that the T_m only depends on the crystalline temperature. On the other hand, with the increasing temperature up to above 343 K for solvent evaporating, two melting peaks at 356 and 377 K were observed for the crystallization of PVCH-PE-PVCH in the solution. It resulted in that the crystallization and the microphase separation of the block copolymer occurred simultaneously. And the confined and unconfined crystallization coexisted for the samples. The competition of the crystallization and the microphase separation can be controlled through changing the solvent evaporating speed.
文摘The melting and recrystallization behaviour of poly（vinylcyclohexane）-b-poly（ethylene）-b-poly（vinylcyclohexane）（PVCH-PE-PVCH） triblock copolymer in supercritical carbon dioxide(CO2) was investigated by（using） of DSC.The effect of the rate of the depressurization of CO2 on the crystallization of the samples was also examined.It is found that there are three melting peaks on each DSC curve of the samples treated in supericritical CO2 at the temperature above tm of the untreated PVCH-PE-PVCH.They corresponded to the 'hard' confined crystallization of PE blocks homogeneous nucleation,the 'soft' confined crystallization of PE blocks homogeneous nucleation and the self-seeding nucleation free crystallization of PE blocks respectively.Furthermore,these three kinds of crystallization could be controlled by changing the competition between the crystallization of PE block and the vitrifaction of PVCH block in the samples,which depended on the rate of the depressurization of CO2.
