Synthesis and characterization of α,ω-dihydroxy-telechelic oligo(p-dioxanone)

Abstract

The homopolymer of 1,4-dioxane-2-one (pDO) is well known as an established biomaterial, especially for degradable surgical sutures. Well-defined α,ω-dihydroxy telechelics based on pDO are introduced in this paper. pDO was synthesized via a one step reaction modified to a literature procedure with a yield of 50–60%. The monomer was polymerized in bulk to oligomeric products via ring-opening polymerization. The polymerization was performed without or with dibutyltin oxide as catalyst using low molecular weight alcohols as initiators. The oligomeric products have number average molecular weights (M_n) between 1800 g mol^–1 and 4200 g mol^–1. They were soluble in 1,2-dichloroethane or chloroform as common solvents for further reaction in solution. The α,ω-dihydroxy-functionality of the obtained telechelics was investigated by MALDI-TOF MS and ¹H NMR spectroscopy. Polymerization in the presence of the catalyst lead to macrocyclic byproducts which have been detected by MALDI-TOF MS. The telechelics were semicrystalline with melting points T_m between 86 °C and 95 °C, increasing with increasing molecular weight. The melting enthalpies ΔH_m ranged from 67.7 to 82.3 J g^–1. An example of the synthetic opportunities arising from the availability of well-defined telechelic oligomers as starting materials are multiblock copolymers, which were synthesized successfully from oligo(p-dioxane)diol, poly[(rac-lactide)-ran-glycolide]diol and trimethylhexane diisocyanate with weight average molecular weights M_w between 62 000 and 149 000 g mol^–1.