Sol - Gel Prepared Low Shrinkage Of Pmma / Sio <sub> 2 </ Sub> Hybrid Materials And Performance

Organic-inorganic hybrid materials have become one of the quite popular subjects in material research fields. This kind of materials has applications in many fields such as mechanics, thermodynamics, optics, electromagnetism, chemistry and biology because they summarize the characteristics of organic and inorganic materials.With the advantages of mild reaction conditions and multiplex synthesis routines, Sol-gel method has greatly facilitated the manufacture of PMMA/SiO2 hybrid materials. However, two serious shortcomings must be overcome in preparing bulky hybrid materials: 1, due to the poor miscibility of the two phases, the macroscopic phase separation is rather easily to take place, and thus deteriorate the performances of the materials. 2, the volume shrinkage during the preparing processes is inevitable, which makes the shape and size controlling of the materials become difficult.In this thesis, MMA and TEOS as the primer materials are taken to manufacture low shrinkage, high light performance bulky PMMA/SiO2 hybrid material. In order to reduce the possible volume shrinkage, a few special methods have been adopted: minimizing the quantity of water as possible in TEOS hydrolyzing, pre-polymerization the organic monomers, mixing inorganic pre-cursors and pre-polymerized organic monomers under a non-co-solvent condition and the small molecular species are removed with a step by step drying. Furthermore, in order to improve the miscibility of the organic and inorganic species, one type of silane coupling agent (KH-570) which hydrolyzed simultaneously with TEOS has been put into the system.The volume shrinkage depends on the composition of the systems. It varies from 2% to 26% and tends to increase with increasing the proportionality of the inorganic material. The measures adopted in the preparing process are favorable in reducing the volume shrinkage and the volume shrinkage origins mainly from the residual Si-OH.The micro-structure and a few performances of the PMMA/SiO2 hybrid materials were characterized with several methods. The existence of covalent bonds between organic phase and inorganic phase and the forming of homogeneous inter-penetrated network showed that the miscibility of the two species has been improved greatly.