ISSN:
0887-624X
Schlagwort(e):
cationic polymerization
;
cyclic ketene acetal
;
1,2-vinyl addition polymerization
;
2-methylene-1,3-dioxolane
;
2-methylene-1,3-dioxane
;
2-methylene-5,5-dimethyl-1,3-dioxane
;
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Pure 1,2-addition polymers, poly(2-methylene-1,3-dioxolane), 1b, poly(2-methylene-1,3-dioxane), 2b, and poly(2-methylene-5,5-dimethyl-1,3-dioxane), 3b, were prepared using the cationic initiators H2SO4, TiCl4, BF3, and also Ru(PPh3)3Cl2. Small ester carbonyl bands in the IR spectra of 1b and 2b were observed when the polymerizations were performed at 80°C (1b) and both 67 and 138°C (2b) using Ru(PPh3)3Cl2. 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 290°C (1b), 240°C (2b), and 294°C (3b). Different chemical shifts for axial and equatorial H and CH3 on the ketal rings were found in the 1H NMR spectrum of 3b at room temperature. High molecular weight 3b (M̄n = 8.68 × 104, M̄w = 1.31 × 105, M̄z = 1.57 × 105) was obtained upon cationic initiation by H2SO4. Poly(2-methylene-1,3-dioxane), 2b, underwent partial hydrolysis when Ru(PPh3)3Cl2 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(2-methylene-1,3-dioxane). No crosslinked or aromatic structures were observed in the hydrolyzed products. The molecular weight of hydrolyzed polymer was M̄n = 5740, M̄w = 7260, and M̄z = 9060. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3707-3716, 1997
Zusätzliches Material:
4 Ill.
Materialart:
Digitale Medien
Permalink
