title: Shape-memory polymer networks from oligo[(epsilon-hydroxycaproate)-co-glycolate]dimethacrylates and butyl acrylate with adjustable hydrolytic degradation rate.
abstract: Degradable shape-memory polymer networks intended for biomedical applications were synthesized from oligo[(epsilon-hydroxycaproate)-co-glycolate]dimethacrylates with glycolate contents between 0 and 30 mol % using a photopolymerization process. In addition AB copolymer networks were prepared by adding 60 wt % n-butyl acrylate as comonomer. All synthesized polymer networks are semicrystalline at room temperature. A melting transition T(m) between 18 and 53 degrees C which can be used as switching transition for the shape-memory effect can be attributed to the crystalline poly(epsilon-hydroxycaproate) phase. At temperatures below T(m) the elastic properties are dominated by these physical cross-links. At temperatures higher than T(m) the E modulus of the amorphous polymer networks is lowered by up to 2 orders of magnitude, depending on the chemical cross-link density. Copolymer networks based on macrodimethacrylates with a M(n) of up to 13,500 g x mol(-1) and a maximum glycolate content of 21 mol % show quantitative strain recovery rates in stress-controlled cyclic thermomechanical experiments. Hydrolytic degradation experiments of polymer networks performed in phosphate buffer solution at 37 degrees C show that the degradation rate can be accelerated by increasing the glycolate content and decelerated by the incorporation of n-butyl acrylate.
authors.affiliation: GKSS Research Center, Center for Biomaterial Development, Institute of Polymer Research, 14513 Teltow, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Kelch
authors.forename: Susi
authors.initials: S
authors.lastname: Steuer
authors.forename: Annette M
authors.initials: AM
authors.lastname: Schmidt
authors.forename: Andreas
authors.initials: A
authors.lastname: Lendlein
mesh_terms: D000179:Acrylates / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000494:pharmacology; D005782:Gels; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D046911:Macromolecular Substances / Q000737:chemistry; D008689:Methacrylates / Q000737:chemistry*; D015233:Models, Statistical; D011091:Polyesters / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D000179:Acrylates; D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D005782:Gels; D046911:Macromolecular Substances; D008689:Methacrylates; D011091:Polyesters; D011108:Polymers; C520966:poly((epsilon-hydroxycaproate)-co-glycolate)dimethacrylate; D014867:Water; C032490:n-butyl acrylate