The Synthesis Of Q_xM_y POSS And Properties Of Its Composites With PMMA

Polyhedral Oligomeric Silsesquioxanes(POSS)has a unique organic-inorganic hybrid structure,with the structure designability,good organic compatibility and other advantages,and has shown great application potential in the thermal and mechanical properties of modified polymer.In this thesis,aiming at the disadvantages of limited application such as poor heat resistance of polymethyl methacrylate(PMMA),We used different kinds of POSS to modify it,and explored the synthesis process of OxMy POSS and the influence mechanism of POSS added to PMMA on thermal and mechanical properties of materials.The main work includes the following aspects.Firstly,the intermediate TMN-POSS prepared by Q_xM_y POSS was synthesized by sol-gel method,and TMN-POSS was functionalized by dimethyl vinyl chlorosilane and methylacryl chloride has synthesized multi-functionalized Ovi-POSS and MAS-POSS.By exploring the amount of functionalized reagent,solvent,the reaction time,we determined that the optimal synthesis conditions of Ovi-POSS were molar ratio of dimethyl vinyl chlorosilane to TMN-POSS was 20:1,and solvent was n-hexane and methanol(volume ratio is 1:2),reaction time was 2h.The results of mass spectrometry and GPC showed that the product composition of Ovi-POSS was single and the yield was 67.7%.By exploring the amount of functionalized reagent,solvent,we determined that the functional preparation of MAS-POSS is proved to be feasible,The preferred solvents of MAS-POSS were n-hexane and dimethyl sulfoxide(volume ratio:1:2).The MS results showed that when the molar ratio of methacryl chloride to TMN-POSS was 20:1,the number of functional groups in POSS was mainly 7;when the molar ratio of methacryl chloride to TMN-POSS was 10:1,the number of functional groups in POSS was mainly 4.Secondly,we added the above functionalized QxMy POSS(Ovi-POSS,MAS-POSS)to PMMA for modification by means of free radical polymerization,and explored the influence of QxMy POSS on the thermal and mechanical properties of PMMA.Furthermore,we compared the modified effects of T_n vinyl POSS(Ovi-POSS)and methacrylenoxy POSS(MA-POSS)on PMMA.Through FTIR and XRD characterization,it is proved that all four POSS can be introduced into PMMA in the way of chemical copolymerization.The addition of Ovi-POSS and MA-POSS maked the polymer cross-linked;SEM results showed that microphase separation occurred in Ovi-POSS/PMMA;TG,DTG,DSC analysis results showed that the addition of four kinds of POSS can improve PMMA’s heat resistance and glass transition temperature,and we analyzed the mechanism of POSS affecting PMMA’s thermal properties.The test results of mechanical properties(bending and stretching)proved that the introduction of Ovl-POSS can improve both bending and tensile properties of materials,the strength increased gradually with the increase of addition amount,and we analyzed the mechanism of POSS affecting PMMA’s mechanical properties.