Synthesis Of Functionalized Polyhedral Oligomeric Silsesquioxane And Studies On Preparation And Properties Of POSS/PMMA Hybrid Materials

Polyhedral oligomeric silsesquioxane（POSS）has organic/inorganic properties,and the internal Si-O-Si has good heat stability.POSS is applied to the polymer.When the reaction temperature is raised,the molecular structure of POSS is not destroyed,so that the polymer material properties are obtained improve.However,due to the many influencing factors in the preparation process of POSS,it is difficult to separate and purify,which makes its application cost higher,which limits its development to a certain extent.PMMA is transparent,non-toxic and harmless,and has a wide range of applications in many occasions.However,due to its poor stability and poor high temperature performance,PMMA has limited its use in high-precision fields.In this paper,two functionalized POSS were firstly prepared.The factors affecting the synthesis of POSS were discussed,the synthesis conditions were optimized.The two POSS were applied in the polymerization of MMA to improve the material and prepare POSS/PMMA hybrid materials.Discussed the effect of POSS addition on the properties of hybridmaterials.The specific research contents and results of this paper are as follows:（1）Usingγ-Methacryloxypropyl trimethoxysilane（KH570）as raw material,hydrochloric acid as catalyst,anhydrous ethanol as reaction solvent,reaction temperature of 38℃,reaction time of 48h,percentage of raw material mass the total mass is 20%.When the amount of water is 20%of raw material,T₈^MA-POSS is obtained.The appearance is transparent yellowishviscous liquid,the systemcan exist stably,and the reaction yield reaches the maximum value 30%,the structure and design of T₈^MA-POSS were characterized by FT-IR,¹H-NMR,²⁹Si-NMR and so on.（2）MMA radical polymerization,when amount of initiator AIBN is 0.1%,the reaction temperature is 75⁸0℃,the reaction is controllable,the obtained PMMA is transparent,molecular weight is large and the evenly distributed;X-ray diffraction（XRD）results show T₈^MA-POSS-co-PMMA hybrid material exhibits abroad diffraction peak,which is characterized by amorphous structure diffraction angle of PMMA at 14.4°,diffraction angle increases to 16.4°,when polyhedral oligomeric silsesquioxane（POSS）content is 10%.the glass transition temperature（DSC）measurementresultsshowthePMMA glass transition temperature is 91.73℃,the introduction of polyhedral oligomeric silsesquioxane（POSS）increases glass transition point of the material.When the amount of T₈^MA-POSS is 10%,the glass transition temperature is increased to 120.83℃,which improved 29.1℃;heat stability analysis showed that initial decomposition temperature of PMMA was 179.85℃,introduction of POSS improved heat stability hybrid materials.When the amount of POSS added 10%,the decomposition temperature increased to 208.29℃,the temperature is28.44℃improve,decomposition temperature is increased from401.77℃to 461.2℃of PMMA,increasing by 59.5℃;transparency of PMMA can reach 92%,the effect of T₈^MA-POSS addition on its light transmission is relatively small,when the amount of addition is 10%,light transmittance is 85%.（3）Using tetraethoxysilane（TEOS）,tetramethyl ammonium hy droxide（TMAH）as raw material,anhydrous ethanol as solvent,hyd rolysis reaction at 60℃obtain precursor hydrolysis quaternized po lyhedral oligomeric silsesquioxane（POSS）,the rate can be up to 85%,and the polyhedral oligomeric silsesquioxane（POSS）is grafted with dimethyl hydrochlorosilane（（CH₃）₂ClSiH）at 0⁴℃to obtain functionalized Si-H-POSS.It′s identified by modern analytical as FT-IR,¹H-NMR,²⁹Si-NMR,TEM,AFM.（4）Free radical polymerization of Si-H-POSS and MMA to obtain Si-H-POSS-co-PMMA hybrid materials.X-ray diffraction（X RD）results show that hybrid material exhibits a broad diffraction peak with an amorphous structure,the diffraction angle of PMMA is 14.4°,and the diffraction angle is increase to 16.1°when th e POSS content is 20%.The glass transition temperature（DSC）m easurement showed that when the addition amount of Si-H-POSS i s 20%,the glass transition temperature is increased to 122.79℃,which is 31.06℃higher than that of PMMA.Heat stability analys is shows that when the amount of Si-H-POSS is 20%,the decomp osition temperature increases to 240.09℃,which increases 66.24℃,and the decomposition temperature is high as 501.51℃,increased99.74℃,through adjunction of Si-H-POSS improves the heat stab ility of hybrid materials.As Si-H-POSS added to the material the light transmittance is slightly decreased,when the addition amount is 20%the light transmittance is reduce to 72%.