Cationic 1,2-vinyl addition polymerization of cyclic ketene acetals initiated by conventional acids

✍ Scribed by Yuxia Liu; Charles E. Keller; Charles U. Pittman Jr.

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 195 KB
• Volume: 35
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(199712)35:17<3707::aid-pola10>3.0.co;2-h

✦ Synopsis

Pure 1,2-addition polymers, poly(2-methylene-1,3-dioxolane), 1b, poly(2methylene-1,3-dioxane), 2b, and poly(2-methylene-5,5-dimethyl-1,3-dioxane), 3b, were prepared using the cationic initiators H 2 SO 4 , TiCl 4 , BF 3 , and also Ru(PPh 3 ) 3 Cl 2 . Small ester carbonyl bands in the IR spectra of 1b and 2b were observed when the polymerizations were performed at 80ЊC (1b) and both 67 and 138ЊC (2b) using Ru(PPh 3 ) 3 Cl 2 . The poly(cyclic ketene acetals) were stable if they were not exposed to acid and water. They were quite thermally stable and did not decompose until 290ЊC (1b), 240ЊC (2b), and 294ЊC (3b). Different chemical shifts for axial and equatorial H and CH 3 on the ketal rings were found in the 1 H NMR spectrum of 3b at room temperature. High molecular weight 3b (M V n Å 8.68 1 10 4 , M V w Å 1.31 1 10 5 , M V z Å 1.57 1 10 5 ) was obtained upon cationic initiation by H 2 SO 4 . Poly(2-methylene-1,3dioxane), 2b, underwent partial hydrolysis when Ru(PPh 3 ) 3 Cl 2 and water were present in the polymer. The hydrolyzed products were 1,3-propanediol and a polymer containing both poly(2-methylene-1,3-dioxane) and polyketene units. The percentages of these two units in the hydrolyzed polymer were about 32% polyketene and 68% poly(2methylene-1,3-dioxane). No crosslinked or aromatic structures were observed in the hydrolyzed products. The molecular weight of hydrolyzed polymer was M V n Å 5740, M V w