title: Photopolymerization and shrinkage kinetics of in situ crosslinkable N-vinyl-pyrrolidone/poly(epsilon-caprolactone fumarate) networks.
abstract: Biodegradable, injectable and in situ photocrosslinkable macromers based on fumaric acid and polycaprolactone (PCLF) were prepared and characterized by FTIR, 1HNMR, and 13CNMR spectroscopy. The multifunctional macromers dissolved in N-vinyl pyrollidone (NVP) were photopolymerized by visible light irradiation in the presence of camphorquinone as photoinitiator. The photocrosslinking reaction was monitored by measuring shrinkage strain and shrinkage strain rate. The degree of photopolymerization reaction i.e. degree of conversion (DC%) was traced using FTIR spectroscopy. A three level factorial design was developed to study the effects of initiator concentration, NVP concentration, and molecular weight of PCLF upon photocrosslinking characteristics including degree of conversion and shrinkage strain. Results revealed that although neat PCLF was photopolymerized, but it was putty like after 220 seconds of irradiation and showed a very low degree of conversion (29%). Adding about 20% NVP caused a dramatic increase in its degree of conversion (63.33%). Increasing NVP up to 50% resulted in a decrease in DC% because of lower reactivity of NVP and leaving more unreacted NVP monomers. Sol fraction studies supported these results indicating that at higher NVP concentration, most of NVP and PCLF have not undergone the crosslinking reaction, leading to 55% decrease in DC%. Shrinkage strain measurement also confirmed the FTIR results.
authors.affiliation: Biomedical Engineering Department, Amirkabir University of Technology, PO Box 15875/4413, Tehran, Iran.
authors.forename: Shahriar
authors.initials: S
authors.lastname: Sharifi
authors.forename: Hamid
authors.initials: H
authors.lastname: Mirzadeh
authors.forename: Mohammad
authors.initials: M
authors.lastname: Imani
authors.forename: Mohammad
authors.initials: M
authors.lastname: Atai
authors.forename: Farshid
authors.initials: F
authors.lastname: Ziaee
mesh_terms: D002254:Carbonates / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003432:Cross-Linking Reagents; D003460:Crystallization; D005650:Fumarates / Q000138:chemical synthesis* / Q000528:radiation effects; D007202:Indicators and Reagents; D007700:Kinetics; D008027:Light; D008970:Molecular Weight; D010777:Photochemistry; D011091:Polyesters / Q000138:chemical synthesis* / Q000528:radiation effects; D011188:Potassium / Q000737:chemistry; D011205:Povidone / Q000138:chemical synthesis* / Q000528:radiation effects; D011522:Protons; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics
chemical_list: D002254:Carbonates; D003432:Cross-Linking Reagents; D005650:Fumarates; D007202:Indicators and Reagents; D011091:Polyesters; D011522:Protons; C506476:poly(caprolactone fumarate); C037593:potassium carbonate; D011205:Povidone; D011188:Potassium