The work in this study was to synthesize and characterize some models and aseries of polymers and to study their thermal properties, the work had been divided into two parts , the first one includes preparation of three models: 1. Bis (trimethylsiloxanyl) 2,2,2-trichloroethane. 2.Tris (trimethylsilyl) triethanolamine. 3 . Bis (trimethylsilyl) diethanolamine . From the reaction of trimethylchlorosilane with chloral hydrate, triethanolamine and diethanolamine respectively, all were identified by their IR and mass spectra. Ten polymers were prepared from the reaction of dimethyldichlorosilane, .diphenyklichlorosilane and tetrachlorosilane with the compounds mentioned above respectively, as well as the preparation of poly(Bis (phenylvinylsiloxanyl)2,2,2- trinhloroehane) as a result of the reaction of chloral hydrate with phenylvinyldichlorosilane. These were characterized by IR spectra and elemental analysisis. Some of the polymers synthesized were found to be thermally stable when studies by thermal gravimetric analysis (TGA) . The work in the second part of this thesis includes the prepration of two monomers :- 1.2,5-Bis (4-hydroxy phenyl) thiazolo [5,4-d] thiazole .2. 2,5-Bis (4-hydroxy-3-methoxy phenyl) thiazolo [5,4-d] thiazole . The first one was characterized by IR, N.M.R. spectra and (C.H.1SI) analysis, while the second one was identified by using IR, mass spectra and (C.H.N) analysis. These two monomers above were used to prepare two models and six polymers from their reaction with the silicon compounds mentioned previously , these models and polymers are (STT, SVTT, PDMSTT, PDPSTT, PTSTT, PDMSVTT, PDPSVTT and PTSVTT respectively ) . The two models were identified by IR and mass spectra, while the polymers were characterized by IR and elemental analysis. Liquid crystalline properties of the compounds above were studied using,differential scaning calorimetry (DSC) and hot stage microscope. The two models didn' t show any sign of liquid-crystalline properties, but the polymers showed a nematic phase .