title: Oligo(epsilon-caprolactone)-based polymer networks prepared by photocrosslinking in solution.
abstract: OBJECTIVE
  Polymer networks with adjustable properties prepared from endgroup-functionalized oligoesters by UV-crosslinking in melt have evolved into versatile multifunctional biomaterials. In addition to the molecular weight or architecture of precursors, the reaction conditions for crosslinking are pivotal for the polymer network properties. Crosslinking of precursors in solution may facilitate low-temperature processes and are compared here to networks synthesized in melt.
  
  
  METHODS
  Oligo(epsilon-caprolactone)-(z)methacrylate (oCL-(z)IEMA) precursors with a linear (z = di) or a four-armed star-shaped (z = tetra) architecture were crosslinked by radical polymerization in melt or in solution with UV irradiation. The thermal, mechanical, and swelling properties of the polymer networks obtained were characterized.
  
  
  RESULTS
  Crosslinking in solution resulted in materials with lower Young's moduli (E), lower maximum stress (σmax), and higher elongation at break (epsilonB) as determined at 70 °C. Polymer networks from 8 kDa star-shaped precursors exhibited poor elasticity when synthesized in the melt, but can be established as stretchable materials with a semi-crystalline morphology, a high gel- content, and a high elongation at break when prepared in solution.
  
  
  CONCLUSIONS
  The crosslinking condition of methacrylate functionalized precursors significantly affected network properties. For some types of precursors such as star-shaped telechelics, synthesis in solution provided semi-crystalline elastic materials that were not accessible from crosslinking in melt.
authors.affiliation: Center for Biomaterial Development and Berlin-Brandenburg Centre for Regenerative Therapies, Institute of Polymer Research, Helmholtz-Zentrum Geesthacht, Teltow, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Friess
authors.forename: Christian
authors.initials: C
authors.lastname: Wischke
authors.forename: Marc
authors.initials: M
authors.lastname: Behl
authors.forename: Andreas
authors.initials: A
authors.lastname: Lendlein
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D003460:Crystallization; D055119:Elastic Modulus; D005782:Gels / Q000737:chemistry; D008689:Methacrylates / Q000737:chemistry; D044367:Phase Transition; D011091:Polyesters / Q000737:chemistry*; D058105:Polymerization; D012996:Solutions / Q000737:chemistry; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D005782:Gels; D008689:Methacrylates; D011091:Polyesters; D012996:Solutions; C016240:polycaprolactone