Cyclic ureas as solvents for esterification of poly(vinyl alcohol) and vinyl acetate-vinyl alcohol copolymers with acid chlorides

✍ Scribed by M. D. Fernández; M. J. Fernández

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 181 KB
• Volume: 107
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.27362

✦ Synopsis

Abstract

Poly(vinyl alcohol) (PVAL) and vinyl acetate‐vinyl alcohol copolymers (VAVAL) were esterified with 3,5‐dinitrobenzoyl chloride using the cycled urea N,N′‐dimethylpropyleneurea (1,3‐dimethyl‐3,4,5,6‐tetrahydro‐2(1H)‐pyrimidinone) (DMPU) as the solvent. Vinyl alcohol‐vinyl‐3,5‐dinitrobenzoate copolymers (VALVDNB) and vinyl acetate‐vinyl‐3,5‐dinitrobenzoate copolymers (VAVDNB) were obtained. High degrees of esterification were obtained when PVAL was esterified (86%). The degree of transformation was determined by ^1^H‐NMR as well as by chemical analysis, and the structure of the resulting polymers by means of IR spectroscopy and ^1^H‐ and ^13^C‐NMR. The microstructure of PVA, PVAL, VAVAL copolymers and VALVDNB copolymers were determined from ^1^H‐ and ^13^C‐NMR techniques. The sequence distributions for VAVAL copolymers prepared by base‐catalyzed transesterification of PVA were blocky, while the distributions were close to random for VALVDNB copolymers obtained by esterification of PVAL. Thermal properties were studied by DSC. The T~g~ values of VAVAL, VALVDNB, and VAVDNB copolymers as a function of copolymer compositions were determined. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008