Study On The Transition Behavior Of Polymer PCM In Nanostructured Silica

The research on the behavior of polymer in a confined environment has been a focal field in recent years. In order to understand the confinement effects of triblock copolymer with crystalline block, we prepared nanostructured silica containing the PEO-PPO-PEO triblock copolymer (F108, F88) and investigated the thermal transition of crystalline block.In case of by using F108 template solution, the results of SAXS and TEM show that the silica structure has well- ordered bicontinuous cubic, Im3m (a = 23.3nm).Combined XRD and DSC proves that crystal structure in silica nanostructure is preserved and DSC measurement show melting temperature depression and double melting transition of PEO block.. Melting temperatures, 23.6℃ and 26.7℃ are lower than that of bulk state.When we used F88 (PEO100-PPO39-PEO100) as template solution, silica structure by analyzed SAXS /TEM experiments has well- ordered bicontinuous cubic (a = 25nm). In the other hand, the result of XRD and DSC indicated that crystallinity of PEO block is not kept in nanopore of silica. XRD/DSC measurements reveal that PEO block of F88 dose not have crystal structure in nanostructured silica.Although confined environment of F88 is similar to that of F108, the reason why crystal structure of PEO F88 is not preserved is that the molecular weight of F88 PEO block is lower than that of F108. These results imply that the triblock copolymers chain not only is confined by the nano structured silica but also has large surface contacting with silica wall.In this paper ,we researched on on the transition behavior of polymer PCM, in nanostructured silica, its theory guidance to prepare nano polymer PCM is significance.