Characterization, degradation, and mechanical strength of poly(D,L-lactide-co-ϵ-caprolactone)-poly(ethylene glycol)-poly(D,L-lactide-co-ϵ-caprolactone)

Authors

  • Hanna Bramfeldt,

    1. Laboratoire de Bioingénierie et de Biophysique de l'Université de Sherbrooke, Department of Chemical Engineering, Université de Sherbrooke, 2500, blvd de l'Université, Sherbrooke, Quebec, Canada J1K 2R1
    2. Research Centre on Aging, Institut universitaire de gériatrie de Sherbrooke, 1036, rue Belvédère Sud, Sherbrooke,Quebec, Canada J1H 4C4
    Search for more papers by this author
  • Pierre Sarazin,

    1. Laboratoire de Bioingénierie et de Biophysique de l'Université de Sherbrooke, Department of Chemical Engineering, Université de Sherbrooke, 2500, blvd de l'Université, Sherbrooke, Quebec, Canada J1K 2R1
    2. Research Centre on Aging, Institut universitaire de gériatrie de Sherbrooke, 1036, rue Belvédère Sud, Sherbrooke,Quebec, Canada J1H 4C4
    Search for more papers by this author
  • Patrick Vermette

    Corresponding author
    1. Laboratoire de Bioingénierie et de Biophysique de l'Université de Sherbrooke, Department of Chemical Engineering, Université de Sherbrooke, 2500, blvd de l'Université, Sherbrooke, Quebec, Canada J1K 2R1
    2. Research Centre on Aging, Institut universitaire de gériatrie de Sherbrooke, 1036, rue Belvédère Sud, Sherbrooke,Quebec, Canada J1H 4C4
    • Laboratoire de Bioingénierie et de Biophysique de l'Université de Sherbrooke, Department of Chemical Engineering, Université de Sherbrooke, 2500, blvd de l'Université, Sherbrooke, Quebec, Canada J1K 2R1
    Search for more papers by this author

Abstract

A series of three biocompatible P(CL-co-LA)-PEG-P(CL-co-LA) copolymers were synthesized using ring-opening polymerization and characterized by 1H-NMR, gel permeation chromatography, DSC, dynamic-mechanical analysis, and X-ray diffraction. The number of monomer units was kept constant, while the D,L-LA fraction was varied so as to constitute 0, 30, or 70% of the end segments. The molecular weights were sufficiently high to eventually permit 3D scaffold preparation. A degradation study was carried out over 26 weeks, and the effect of monomer composition on the rate of degradation as well as on changes in mechanical strength was investigated. Pure polycaprolactone (PCL)-poly(ethylene glycol) (PEG)-PCL copolymer, P(100/0), was a crystalline material displaying no measurable mass loss, a 30% reduction in mean molecular weight (Mn), and only very slight changes in tensile strength. The random incorporation of 30 and 70% D,L-LA into the end sections of the polymer chain, produced more and more amorphous materials, exhibiting increasingly high rates of degradation, mass loss, and loss of tensile strength. Compared with random P(CL-co-LA), the presence of the PEG block was found both to improve hydrophilicity and thus the rate of degradation and to infer a stabilizing quality, thereby pacing the decrease in tensile strength during degradation. The tested copolymers range from materials exhibiting low mechanical strength and high rate of degradation to slow-degrading materials with high mechanical strength suitable, e.g., for three-dimensional scaffolding. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007

Ancillary