Synthesis and characterization of degradable triarm low unsaturated poly(propylene oxide)‐block‐polylactide copolymers

Abstract

A series of novel degradable triarm poly-(propylene oxide)-block-polylactide (PPO-b-PLA) copolymers was synthesized by ring-opening polymerization of L-lactide (LLA) or D,L-lactide (DLLA) using low unsaturated PPO triols as macromolecular initiator. The chemical structures of the resulting copolymers were characterized by Fourier transform infrared (FTIR), gel permeation chromatography (GPC), and proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy. Combination of FTIR, GPC, and NMR results confirmed the formation of PPO-b-PLA copolymers. One glass transition was observed by differential scanning calorimetry (DSC), suggesting good miscibility between PPO and PLA segments in the copolymers. DSC and wide-angle X-ray diffraction demonstrated that PPO-b-PLLA copolymers were semicrystalline materials, and the crystallinity increased with increasing the PLLA content. In contrast, PPO-b-PDLLA copolymers were totally amorphous. The PPO-b-PLA copolymers exhibited improved thermal stability when compared with PPO polyols according to thermogravimetric analysis. The thermal degradation behavior of the copolymers depended on the composition. Polyurethane foams were prepared by crosslinking PPO and PPO-b-PLA copolymers using isocyanate. Alkaline degradation of the foams was investigated in 10 wt/vol % NaOH at 80 C. The results show that the novel PPO-b-PLA copolymers could be promising as degradable polymeric materials.

Preparation and properties of novel poly(propylene oxide)‐block‐polylactide‐based polyurethane foams

“…Both L ‐ and DL ‐lactide monomers were synthesized by a two‐step procedure [ 13]: First, oligomer of PLA was synthesized by polycondensation at high temperatures and reduced pressures, and lactide was then formed by depolymerization of the corresponding oligomer, which was catalyzed by zinc powder.…”

“…The polymerization of lactide was carried out via ring‐opening polymerization (ROP) with poly(propylene oxide) triol as initiator according to a method reported in our previous work [ 13]. The ROP was catalyzed by stannous octoate (0.1 wt%).…”

Biodegradable Polylactide‐Based Composites

“…Modification in the synthesis process with other monomers is other way to tune the properties of polylactides. Comonomers as etylenglycol or ethylene oxide [49,50], propylene oxide [51] and trimethylcarbonate [52] have been reported for polymerization with lactide units. However, cyclic comonomers are suitable to polymerize by ring opening polymerization (ROP) with lactide such as lactones or macrolactones.…”

Effect of poly(l‐lactide)/poly(d‐lactide) block length ratio on crystallization behavior of star‐shaped asymmetric poly(l(d)‐lactide) stereoblock copolymers

“…For the preparation of 1 H NMR specimens, mixture of chloroform-d and 1,1,1,3,3,3-hexafluoro-2-propanol (vol/vol 5 95/5) was used as the solvent. The M n (NMR) values of the synthesized copolymers were estimated by the following equation [27]: M n (PPO-PDLA-PLLA) 5 M n (PPO) 1 72 3 DP PPO 3 (n LA /n PO ), where M n (PPO) 5 3.6 3 10 3 g mol 21 , DP PPO is the degree of polymerization of PPO with a constant of 53, n LA /n PO is the mole ratio of the lactide and propylene oxide units in the PPO-PDLA-PLLA copolymers, which can be estimated from the 1 H NMR spectra. For reference, the molecular weight of PPO-PDLA-PLLA stereoblock copolymers were evaluated in chloroform at 258C utilizing Perk-Elmer Series 200 GPC system (Perk-Elmer, USA) using polystyrene standards.…”