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Hydrolysis of Some Poly(ortho-ester)s in Homogeneous Solutions

1984; Elsevier BV; Volume: 73; Issue: 11 Linguagem: Inglês

10.1002/jps.2600731119

1520-6017

Tue H. Nguyen, Chung Shih, Kenneth J. Himmelstein, Takeru Higuchi,

Advanced Polymer Synthesis and Characterization

The hydrolysis of poly(ortho-ester)s and a monomeric model compound, 3,9-dibenzyloxy-3,9-diethyl-2,4,8,10-tetraoxaspiro[5,5]un decane, was carried out in dioxane-d8-dioxane and followed by 1H-NMR and HPLC, respectively. Experimental results suggested that the polymer degradation proceeds to a large extent via random scission. The hydrolysis was catalyzed by the acid; the catalytic rate constant increased predictably with decreasing aqueous pKa of the acid. The reaction is first order with respect to the catalyst concentration and the number of ortho-ester linkages present, and it is independent of water in the concentration range studied. Strain at the ortho-ester bond may be a factor influencing the hydrolysis rate.