title: Novel injectable and in situ curable glycolide/lactide based biodegradable polymer resins and composites.
abstract: Novel in situ polymerizable liquid three-arm biodegradable oligomeric polyesters based upon glycolic acid (GA), L-lactic acid (LLA), and their copolymers are synthesized and characterized. Injectable and in situ curable polymer neat resins and their composites formulated with bioabsorbable beta-tricalcium phosphate are prepared at room temperature using photo- and redox-initiation systems, respectively. The cured neat resins show the initial compressive yield strength (YCS, MPa), modulus (M, MPa), ultimate compressive strength (UCS, MPa), and toughness (T, kN mm), ranging from 4.0 to 20.1, 201.5 to 730.2, 82.7 to 310.5, and 1.02 to 3.93. The cured composites show the initial YCS, M, UCS and T, ranging from 27.7 to 56.4, 1440 to 4870, 81.6 to 158.9, and 0.94 to 1.97. Increasing GA/LLA ratio increases all the initial compressive strengths of both neat resins and composites. Increasing filler content increases YCS and M but decreases UCS and T. A diametral tensile strength test shows the same trend as a compressive strength test. There seems to be an optimal flexural strength for the composite at the filler content around 43%. An increasing molar ratio increases curing time but decreases the degree of conversion (DC). An increasing filler content increases curing time but decreases exotherm and DC. During the course of degradation, all the materials show a burst degradation behavior within 24 h, followed by an increase in CS. The poly(glycolic acid) neat resin completely loses its strength at around Day 45. The composites completely lose their strengths at different time intervals, depending on their molar ratio and filler content. The degradation rate is found to be molar ratio and filler-content dependent.
authors.affiliation: Department of Biomedical Engineering, Purdue School of Engineering and Technology, Indiana University-Purdue University at Indianapolis Indianapolis, IN 46202, USA. dxie@iupui.edu
authors.forename: Dong
authors.initials: D
authors.lastname: Xie
authors.forename: Jong-Gu
authors.initials: JG
authors.lastname: Park
authors.forename: Jun
authors.initials: J
authors.lastname: Zhao
authors.forename: Charles H
authors.initials: CH
authors.lastname: Turner
mesh_terms: D020341:Absorbable Implants; D001672:Biocompatible Materials / Q000008:administration & dosage* / Q000138:chemical synthesis / Q000737:chemistry*; D003188:Composite Resins / Q000008:administration & dosage / Q000138:chemical synthesis / Q000737:chemistry; D019245:Compressive Strength; D066298:In Vitro Techniques; D007267:Injections; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D015394:Molecular Structure; D011098:Polyglactin 910 / Q000008:administration & dosage* / Q000138:chemical synthesis / Q000737:chemistry*; D012117:Resins, Synthetic / Q000008:administration & dosage / Q000138:chemical synthesis / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013718:Tensile Strength
chemical_list: D001672:Biocompatible Materials; D003188:Composite Resins; D012117:Resins, Synthetic; D011098:Polyglactin 910