Preparation of Nonlinear Optical Poly(Alkyl Vinyl Ethers). 4.<TEX>$^1$</TEX> Synthesis and Characterization of Poly[<TEX>$3^{prime},5^{prime}-dimethoxy-4^{prime}$</TEX>-(2-vinyloxyethoxy)-4-nitrostilbene] and Poly[<TEX>$3^{prime},5^{prime}-dimethoxy-4^{prime}$</TEX>-(2-vinyloxyethoxy)-2,4-dinitrostilbene]

3',5'-Dimethoxy-4'-(2-vinyloxyethoxy)-4-nitrostilbene 2 and 3',5'-dimethoxy-4'-(2-vinyloxyethoxy)-2,4-dinitrostilbene 5 were prepared by the reactions of 2-iodoethyl vinyl ether with 3',5'-dimethoxy-4'-hydroxy-4-dinitrostilbene 1 and 3',5'-dimethoxy-4'-hydroxy-2,4-dinitrostilbene 4, respectively. Monomers 2 and 5 were polymerized with cationic initiators to obtain polymers with 3',5'-dimethoxy-4'-oxy-4-nitrostilbene and 3',5'-dimethoxy-4'-oxy-2,4-nitrostilbene, which are presumably effective chromophores for second-order nonlinear optical application in the side chain. The resulting polymers 3 and 6 were soluble in DMSO and DMF. The inherent viscosities of the polymers were in the range of 0.28-0.33 dL/g in DMSO. Polymers 3 and 6 showed a thermal stability up to 250 ℃ in TGA thermogram, and the Tg values obtained from DSC thermograms were in the range of 81-87°.