Nanosilica particles were directly introduced into polyester polyol resins through in situ polymerization and blending methods, then cured by isophorone diisocyanate (IPDI) trimers to obtain nanocomposite polyurethanes. FTIR and TGA analyses indicated that more polyester segments had reacted with silica particles during in situ polymerization than during the blending method, accompanied by higher T g and more homogeneous dispersion of nanosilica particles in the polymer matrix from in situ polymerization. Maximum values in T g , tensile properties, macrohardness, abrasion resistance, and UV absorbance were obtained when the particle size of silica was about 28 nm. The polyurethane/nanosilica composites obtained by in situ polymerization generally had better mechanical properties than those by the blending method except for some unexpected macrohardness at relatively high silica content.

The quality of heterojunctions at the quantum dot (QD)‐TiO2 nanotube (TNT) interface has important implications on the efficiencies of photoelectrochemical solar cells. Here, it is shown that electrophoretic deposition of pre‐synthesized thioacid‐capped CdTe QDs results in relatively poor charge transfer across the heterojunctions. This is likely due to the intermediate layer of bifunctional linkers (S‐R‐COOH) in between the QDs and TNT. On the other hand, CdTe QD‐sensitized TNT prepared by in situ deposition in aqueous medium provides direct QD‐TNT contact, and hence more favorable heterojunction for charge transfer. This is exemplified not only by the drastic improvement in photocurrent efficiencies, but also provides clear difference on the size‐dependent electron injection efficiencies from the CdTe QDs of different sizes. By extending the system further to CdSe QDs, drastic enhancement is found when carrying out the in situ deposition in an organic medium. The results are discussed in terms of the nature of deposition and the corresponding charge transport characteristics. More importantly, the work reflects the intricacy of the effects of QD size and the quality of the heterojunctions on the overall photoconversion efficiencies.

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