ABA Triblock Copolymers Based on Linear Poly(oxymethylene) and Hyperbranched Poly(glycerol): Combining Polyacetals and Polyethers

The synthesis of hyperbranched-linear-hyperbranched ABA triblock copolymers based on a linear poly(oxymethylene) (POM) block and hyperbranched poly(glycerol) (hbPG) blocks is described. The polymers containing a polyacetal polyether structure were prepared from linear bishydroxy-functional POM macroinitiators, obtained by cationic ring-opening polymerization of trioxane and 1,3-dioxolane as a comonomer with formic acid as a transfer agent and subsequent hydrolysis of the formate group. Partial deprotonation of the resulting hydroxyl groups permitted “hypergrafting” of glycidol by anionic ring-opening multibranching polymerization (ROMBP). With respect to the hyperbranched blocks, the obtained polymers show the expected, moderate molecular weight distributions in the range of 1.31 to 2.01 and molecular weights between 6100 and 22900 g mol–1. Both the degree of polymerization of the linear POM segments as well as the molecular weight of the hbPG blocks have been varied. Key properties, such as thermal behav...