High molecular weight polyesterpolycarbonates and the use thereof for the preparation of bioerosible matrixes for controlled release of drugs

The title polyesterpolycarbonates have general formula (OCO2R1OCO2R2)a [a = 2-300; R1, R2 = polyester residue (R3CO2)x(R4CO2)yR5; x, y = 0-100; (x/x+y)*100 = 0-100, excluding x = y = 0; R3, R4 = C1-4 aliph. hydrocarbon residue; R5 = C2-18 aliph. hydrocarbon residue, C3-8 cycloaliph. hydrocarbon residue, optionally bearing one or more straight or branched alkyl substituents, [CHR6(CH2)nO]mCHR6(CH2)n; R6 = H, Me; n = 1-3 and m = 1-200]. Lactic acid-glycolic acid copolymer (1:1) was treated with triethylene glycol bis(chloroformate) in the presence of N-ethyldiisopropylamine and 4-dimethylaminopyridine in chloroform to give a polymer with intrinsic viscosity 0.729 dL/g.