The influences of intramolecular cyclization on the crosslinking reaction processes and the gel′s swelling ratio in polyvinyl alcohol (PVA)-glutaraldehyde(GA) system were studied. The results show that the intramolecular cyclization is a very important factor that has influence on the formation of PVA networks. The lower PVA concentration, the higher intramolecular cyclization degree and higher critical gelation mixing molecular molar ratio of CHO to OH(r_ c ) were obtained . The intramolecular cyclization fractions were increased with the decrease of PVA concentration. Equilibrium swelling ratio decreased with the increase of PVA concentration at the same extent of reaction and the increase of crosslinker concentration at the same PVA concentration. The formation of network can be adjusted with the change of the PVA concentration or the crosslinker concentration.
Hybrid microballs with polystyrene cores coated by titania nanoparticles were prepared by miniemulsion polymerization. The crystallization morphology and photovoltage properties of the hybrid particles after calcination were characterized by Scanning Electron Microscope(SEM), X-ray diffraction and surface photovoltage spectra(SPS). The crystal morphology has a critical effect on the threshold. It is found that the materials become prous, the thresholds of TiO 2 particles blue-shift with their particle sizes decreasing and crystal phase changing from anatase TiO 2 to rutile TiO 2. The SPS results showed that the peak height was three times the height of common TiO 2 nanoparticles.
