POSS/TiO<sub>2</sub> Nanohybrids as Sun Protection Ingredients for Greenhouse Covers

Abstract

Based on (3-methacryloxypropyl)-Polyhedral oligomeric silsesquioxane (MP-POSS) (MP), vinyl-POSS (VP), (3-glycidoxypropyl)-POSS (GP) and modified with 10, 20 and 30 wt-% titanium tetrabutoxide (TTB), three hybrid nanofilms (f-MPT, f-VPT and f-GPT) were prepared using hydrolytic condensation and crosslinking. The average transparency (AT) and absorption coefficients (AC) of the films were measured in the ranges of 280-2500 nm. The average transparency (AT) values of three films were about 10-11% (280-320 nm), 78-80% (320-400 nm) and 85-89% (750-2500 nm), which implies that these films indeed can provide a physical barrier for blocking the UV-B absorbed into greenhouse, indicating functionality of the POSS/TiO2 materials as the sun protection ingredients. The AT values of three films were in the order of f-MPT>f-GPT>f-VPT due to complete-cage structures of building blocks (POSS) and the size of organic branches covalently bonded to the silica network in the molecular structures. This indicates that VPT powder might be significantly better to selected for the sun protection factor (SPF). Lower mtransparency of the films containing 30 wt-% TTB fractions is ascribed to more amounts of TTB in the modified films.