Synthesis and characterization of polymandelide and lactide/methacrylate block copolymers

We synthesized high molecular weight polymandelide via ring opening polymerization of mandelide, the cyclic dimer of mandelic acid, and characterized its properties. In particular, polymandelide has a glass transition temperature of ∼100°C, higher than any known polylactide, and similar to that of polystyrene (109°C). At pH 7.4 and 55°C, polymandelide samples degrade at ∼1/120 the rate of amorphous polylactide run under the same degradation conditions, and polymandelide's degradation profile matches that for heterogeneous hydrolytic degradation. Copolymerizations of mandelide with racemic lactide resulted in homogeneous materials with glass transition temperatures that range from 60–95°C. Copolymerizations using L-lactide and <12 mol% mandelide yielded semi-crystalline materials, but higher levels of mandelide inhibited crystallization of the L-lactide segments and gave amorphous materials.; Block copolymers of lactide and two methacrylates, methyl methacrylate and methoxy-capped oligo(ethylene glycol) methacrylate (OEGMA), were synthesized via a combination of ring opening polymerization and atom transfer radical polymerization. Poly(lactide)-block-poly(m ethyl methacrylate) synthesized via an end group transformation approach exhibited much higher thermal stability than a comparable polymer prepared from a difunctional initiator. The block copolymers prepared from racemic lactide were homogeneous and exhibited a single glass transition temperature that increased with the mole fraction of poly(methyl methacrylate) in the copolymer. The effect of poly(methyl methacrylate) on the crystallization of the poly(L-lactide) block was also studied. Longer poly(methyl methacrylate) blocks led to a decreased crystallization rate for the poly(L-lactide) block.; Block copolymers of racemic and L-lactide with OEGMA were synthesized using a difunctional initiator. Miscibility of the two blocks increased with decreases in the length of the OEGMA. Block copolymers of L-lactide and OEGMA were used to prepare nanoparticles via dialysis. (Abstract shortened by UMI.)...