“Nanocompoundsite”: Nano phased polymer dispersed in inorganic matrix via covalent bonds

Herein we demonstrate a new strategy to construct inorganic–organic “nanocompoundsite”, i.e., a material that nano phased polymer is dispersed in consecutive inorganic matrix via covalent bonds, which is different from the conventional nanocomposite with polymer as matrix and inorganic nanomaterials as dispersed phase. As a representative system, SiO_x/polydimethylsiloxane (PDMS) nanocompoundsite was prepared from a polymeric precursor of perhydropolysilazane (PHPS) modified by carbohydroxyl end-capped PDMS (HOC-PDMS), through a room-temperature vacuum ultraviolet (VUV) irradiation manner. By adjusting HOC-PDMS/PHPS ratio below 20%, PDMS fully binds to the PHPS derived SiO_x matrix via Si–O–C bond to form the inorganic–organic SiO_x/PDMS nanocompoundsite (ISPN) without noticeable phase separation. The introduction of PDMS into ISPN renders its initial decomposition temperature increase over 110 °C. The remarkable enhancement of thermal stability for PDMS is due to the restriction of terminal hydroxyl induced back-biting reaction and main chain degradation by the inorganic matrix and the covalent binding between PDMS and SiO_x. This novel strategy can further extend to hydroxyl terminated PDMS, polyethylene glycol, and acrylic resin, with the initial decomposition temperature of each polymer increasing by over 110, 150 and 100 °C, respectively. More importantly, the nanocompoundsite combines the characteristics of inorganic matrix and polymer. The coating based on SiO_x/PDMS nanocompoundsite exhibits good flexibility, outstanding interfacial binding strength, ultra-high hardness as well as excellent hydrophobicity.