Bioerodible poly(ortho esters) useful as orthopedic implants or vehicles
for the sustained delivery of pharmaceutical, cosmetic and agricultural agents
from dioxane-based di(ketene acetals). Block copolymers contain these bioerodible
poly(ortho esters). These block copolymers have both hydrophilic and hydrophobic
blocks. They form micelles in aqueous solution, making them suitable for encapsulation
or solubilization of hydrophobic or water-insoluble materials; and they also form
bioerodible matrices for the sustained release of active agents.