Abstract
Polysiloxanes were prepared by acid-catalyzed controlled hydrolytic co-polycondensation of polymethyl(methoxy)siloxanes (PMS) and polymethoxysiloxanes (PMOS) obtained as macromonomers by acid-catalyzed controlled hydrolytic polycondensation of methyl(trimethoxy)silane and tetramethoxysilane, respectively. Co-polycondensation of the macromonomers with molecular weights M w 2000 (PMS) and 400 (PMOS) provided polymethylsiloxane copolymers with molecular weights M w 6500–15,000. The structure was confirmed to consist of block copolymers poly(PMS-block-PMOS) based on the results of gel permeation chromatography, isolation by fractional precipitation with THF and hexane, and 1H and 29Si NMR spectral analyses. The copolymers were soluble in organic solvents, except for hexane, and were fairly stable to self-condensation even without an end block. Transparent and flexible free-standing films were obtained from a 20 wt% THF solution of polymers. The surface morphology of films by FE-SEM and IR microscopic spectral analyses revealed cross-shaped crystalline materials on the film surface of poly(PMS-block-PMOS); these materials consisted of silsesquioxane unit structures depending on the compositions of PMS and PMOS.
Graphical Abstract
Polysiloxanes were prepared by acid-catalyzed controlled hydrolytic co-polycondensation of polymethyl(methoxy)siloxanes (PMS) and polymethoxysiloxanes (PMOS). The structure was confirmed to consist of block copolymers poly(PMS-block-PMOS). The surface morphology of transparent and flexible free-standing films revealed cross-shaped crystalline materials on the film surface of poly(PMS-block-PMOS); these materials consisted of silsesquioxane unit structures depending on the compositions of PMS and PMOS.
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Acknowledgments
This work was supported by a Grant-in-Aid for Scientific Research on Innovative Areas “New Polymeric Materials Based on Element-Blocks (no. 2401)” (24102008A02) from the Ministry of Education, Culture, Sports, Science, and Technology, Japan.
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Gunji, T., Kaburagi, H., Tsukada, S. et al. Preparation, properties, and structure of polysiloxanes by acid-catalyzed controlled hydrolytic co-polycondensation of polymethyl(methoxy)siloxane and polymethoxysiloxane. J Sol-Gel Sci Technol 75, 564–573 (2015). https://doi.org/10.1007/s10971-015-3727-z
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DOI: https://doi.org/10.1007/s10971-015-3727-z