Formation of Ordered Microphase Separation Structure of PS-b-P4VP / POAA Film Blends after Mixed Steam Treatment of Benzene / N-Methylpyrrolidone with Different Volume Ratios

The Advanced Lubrication and Protective Materials R & D Center of Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences has made new progress in the self-assembly of block copolymer / homopolymer blends.

The researchers used the solvent treatment method to realize the orderly self-assembly of the block copolymer (PS-b-P4VP) / homopolymer (POAA, polyamic acid) binary blend film, in which the POAA molecular chain and poly 4- Vinylpyridine (P4VP) blocks have strong hydrogen bonding interactions. The PS-b-P4VP / POAA film blend was placed in benzene / N-methylpyrrolidone (volume ratio 0.97 / 0.03) mixed steam at 80 ℃ for 24 hours to obtain an ordered micro-phase separation structure, in which The spherical domains of styrene are distributed in the P4VP / POAA matrix in an orderly manner. By changing the volume ratio of benzene / N-methylpyrrolidone in the mixed steam, the film self-assembly structure can be adjusted. When the volume ratio of benzene / N-methylpyrrolidone in the mixed steam is 0.99 / 0.01, the polystyrene spherical microdomains are bonded to form an ordered "pearl necklace" -like polystyrene microdomain parallel to the film surface. However, in the absence of solvent vapors, no obvious micro-phase separation was observed for the films that were only heat-treated at 80 ° C.

The AB / C block copolymer / homopolymer hybrid system has always been a research hotspot due to its rich and diverse self-assembled structure and its potential application in the nanometer field. Most of the self-assembled structures of block polymer / homopolymer blends reported previously were obtained by long-term heat treatment at high temperature. However, heat treatment is not suitable for some systems, especially for thermally unstable block polymer / homopolymer blends, as they will crosslink or cure once processed at high temperatures, affecting self-assembly. Solvent treatment is an effective method to control the micro-domain orientation and long-range order in the block copolymer film. This method is simple and does not require any heat treatment.

In this study, the solvent treatment method was extended to the self-assembly of PS-b-P4VP / POAA blend films, which provided new ideas for research in this field.

The research was supported by funding from the important direction project of the Knowledge Innovation Project of the Chinese Academy of Sciences and the national key basic research development planning project. The research results were published in Polymer (51 (2010) 4836e4842).

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