Patent ID: 8182801

Claim:
An ortho ester of a branched water-soluble polymer, wherein the branched water-soluble polymer has two or more polymer arms and the ortho ester (a) is attached to each of the two or more polymer arms, and (b) has the following structure, wherein: (a) is either zero or one; X, when present, is a spacer moiety; (z) is an integer from 1 to 24; R 1 , in each occurrence, is independently H or an organic radical selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, and substituted aryl; R 2 , in each occurrence, is independently H or an organic radical selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, and substituted aryl; and each R 4 is a either (i) an organic radical independently selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, and substituted aryl, or (ii) one or more atoms that combine with another R 4 or the remaining R 4 moieties to form a cyclic ortho ester structure.