title: Thermoresponsive and photocrosslinkable PEGMEMA-PPGMA-EGDMA copolymers from a one-step ATRP synthesis.
abstract: Thermoresponsive and photocrosslinkable polymers can be used as injectable scaffolds in tissue engineering to yield gels in situ with enhanced mechanical properties and stability. They allow easy handling and hold their shapes prior to photopolymerization for clinical practice. Here we report a novel copolymer with both thermoresponsive and photocrosslinkable properties via a facile one-step deactivation enhanced atom transfer radical polymerization (ATRP) using poly(ethylene glycol) methyl ether methylacrylate (PEGMEMA, M(n) = 475) and poly(propylene glycol) methacrylate (PPGMA, M(n) = 375) as monofunctional vinyl monomers and up to 30% of ethylene glycol dimethacrylate (EGDMA) as multifunctional vinyl monomer. The resultant PEGMEMA-PPGMA-EGDMA copolymers have been characterized by gel permeation chromatography (GPC) and 1H NMR analysis, which demonstrate their multivinyl functionality and hyperbranched structures. These water-soluble copolymers show lower critical solution temperature (LCST) behavior at 32 degrees C, which is comparable to poly(N-isopropylacrylamide) (PNIPAM). The copolymers can also be cross-linked by photopolymerization through their multivinyl functional groups. Rheological studies clearly demonstrate that the photocrosslinked gels formed at a temperature above the LCST have higher storage moduli than those prepared at a temperature below the LCST. Moreover, the cross-linking density of the gels can be tuned to tailor their porous structures and mechanical properties by adjusting the composition and concentration of the copolymers. Hydrogels with a broad range of storage moduli from 10 to 400 kPa have been produced.
authors.affiliation: School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom. htai@u.washington.edu
authors.forename: Hongyun
authors.initials: H
authors.lastname: Tai
authors.forename: Wenxin
authors.initials: W
authors.lastname: Wang
authors.forename: Tina
authors.initials: T
authors.lastname: Vermonden
authors.forename: Felicity
authors.initials: F
authors.lastname: Heath
authors.forename: Wim E
authors.initials: WE
authors.lastname: Hennink
authors.forename: Cameron
authors.initials: C
authors.lastname: Alexander
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Shakesheff
authors.forename: Steven M
authors.initials: SM
authors.lastname: Howdle
mesh_terms: D000180:Acrylic Resins / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D003432:Cross-Linking Reagents / Q000494:pharmacology; D020100:Hydrogels / Q000737:chemistry*; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D008738:Methyl Ethers / Q000737:chemistry*; D010777:Photochemistry; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D013314:Stress, Mechanical; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D000180:Acrylic Resins; D003432:Cross-Linking Reagents; D020100:Hydrogels; D008689:Methacrylates; D008738:Methyl Ethers; D011108:Polymers; C542326:poly(ethylene glycol) methyl ether methacrylate-co-poly(propylene glycol) methacrylate-co-poly(ethylene glycol dimethacrylate); C004919:ethylene dimethacrylate