Synthesis and characterization of tetrafunctional lactic acid oligomers: Apotential in situ forming degradable orthopaedic biomaterial

Tetrafunctional lactic acid oligomers with low molecular weight ethylene gl ycol cores were synthesized and characterized to assess their applicability to orthopaedics. Utilizing a visible light photoinitiating system, these o ligomers polymerize within minutes to form highly crosslinked networks and, thus, have potential for in situ formation. Varying the oligomer structure readily alters the physical properties of the resultant polymer networks. For instance, mechanical properties were highly dependent on the number of lactic acid and ethylene glycol units in the oligomer backbone. Additionall y, polymer mass loss ranged from similar to 30 to 60% within 8 weeks of deg radation time depending on the oligomer chemistry. Mechanical properties de creased with degradation of these polymers, indicating a bulk degradation m echanism. Finally, scaffolds with a controlled architecture were fabricated from these oligomers that show potential for tissue-engineering applicatio ns. (C) 2001 John Wiley & Sons, Inc.