Block polyacetal systems

The second generation of DES-polyacetals with more controlled solution conformation has recently been described (Gimenez et al., 2012). This includes a family of block polyacetal systems (block-DES), which self-assembled into micellar structures in solution. Both systems, tert- and block-DES, showed clear pH-dependent drug release kinetics. However, the drug release profile was significantly different with a slightly greater DES release and a biphasic mode for block-DBS, indicative of the presence of particulate assemblies (Fig. 11.2a,b). 

Another synthetic strategy is the transformation of ring-opening polymerization to controlled radical polymerization. The transformation of the active site from one to the other can be performed in the polymerization system or after separation and purification. The active sites can be obtained by reacting functionalized polymer with appropriate reagents. Various block copolymers containing polyether (or polyester, or polysiloxane or polyacetal) blocks and vinyl polymer blocks have been prepared by this method. 

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