ABSTRACT
A visible light-mediated sol–gel process can promote the ordering of hexylene, octylene, and decylene-bridged polysilsesquioxane (SQ) with very simple organosilane building blocks having only a short alkylene bridging group: (CH3O)3SiCnH2nSi(OCH3)3 (n = 6, 8, 10). Photocondensation and self-assembly of films are promoted through exposure to a light-emitting diode (LED; 405 nm). The solvent-free synthesis involves very low light intensity (0.1 mW/cm2) and a minimum amount of photoacid generator (PAG; 0.5 wt%) acting as a photocatalyst. X-ray diffraction (XRD) and scanning electron microscopy (SEM) prove the high level of organization, while real-time Fourier transform infrared spectroscopy shows conformational ordering of alkylene chains throughout irradiation. Molecular modeling reveals a multilayer structure based on the stacking of a single polysiloxane chain, with organic groups attached to adjacent Si atoms showing up and down orientation.
Funding
Dr. Lingli Ni would like to thank the financial support from the National Natural Science Foundation of China (No. 51503072, 21606098), and Natural Science Foundation of Jiangsu Province (No. BK20150419).
Supplemental data
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