Synthesis And Characterization Of Functional POSS Monomers

Polyhedral Oligomeric Silsesquioxane (POSS) is a cage-like organic-inorganic hybrid molecular. Unlike clay or silica, POSS has a well-defined and nanoscale structure, it is also compatible with polymers. POSS can composite with polymers at molecular level. POSS modified polymers have enhanced properties. It is very significant to prepare novel polymer-POSS nanohybrids.In order to make POSS used more and more widely in polymer modified fields, a variety of POSS monomers with different structures and properties need to be synthesized. In this thesis, some kinds of new POSS have been synthesized through different methods and the best synthesis route for each POSS has been founded. The main research contents and results are:(1) (C5H9)7T7(OH)3 is synthesized through direct hydrolytic condensation of (C5H9)SiCl3 and (C6H5)7T7(OH)3 is synthesized though corner-opening of (C6H5)8T8. The structures of (C5H9)7T7(OH)3 and (C6H5)7T7(OH)3 are well determined and validated by 1H NMR,13C NMR,29Si NMR, FTIR, Elementary Analysis and MALDI-TOF MS. In the corner-opening reaction of (C6H5)8T8, choosing tetraethyl ammonium hydroxide (TEAOH) as catalyst, when mol(TEAOH):mol((C6H5)8T8) is 1.1:1 and reactants are reflux in THF (66℃) for 4 hours, the product has high purity and yield. Compared with previous work, the reaction time of this synthesis is shorter, the reaction temperature is lower and the yield is higher.(2) C=C-POSS, NH2-POSS, Ti-POSS and Cl-POSS are four kinds of mono-functional POSS which are synthesized through corner-capping reactions of (C6H5)7T7(OH)3 with methacryl propyl trichlorosilane, aminopropyl triethoxysilane, isobutyl titanate and chloropropyl trichlorosilane. Among three kinds of corner-capping reagents, trichlorosilane and isobutyl titanate have high reactivity and short reaction time, triethoxysilane's reactivity is very low and the corner-capping reaction needs to last seven days. Another kind of mono-functional I-POSS is synthesized through reaction between Cl-POSS and NaI.1H NMR,13C NMR,29Si NMR, FTIR and EDS are used to characterize all products. The results proved all the products are synthesized with high purity and yield. TGA results show that all kinds of mono-functional POSS have good thermal stabilities and can be used to modify polymers'thermal properties.(3) C=C-Ti-POSS and NH2-Ti-POSS are two kinds of bi-functional POSS which have more complex structures and better properties, but more difficult to synthesize. In this thesis, they are synthesized through a second corner-opening and corner-capping process of C=C-POSS and NH2-POSS.1H NMR, FTIR and EDS are used to characterize their structures. The results show that C=C-Ti-POSS and NH2-Ti-POSS have been synthesized successfully. TGA results show the thermal stability of C=C-Ti-POSS is between C=C-POSS and Ti-POSS and the thermal stability of NH2-Ti-POSS is between NH2-POSS and Ti-POSS.