Reversibly photo-crosslinkable aliphatic polycarbonates functionalized with coumarin. (August 2018)

• Record Type: Journal Article
• Authors: Chesterman, Julian P.; Hughes, Timothy C.; Amsden, Brian G.
• Is Part Of: European polymer journal. Volume 105(2018)
• Page Start: 186
• Page End: 193
• Publication Date: 2018-08
• Subjects: Trimethylene carbonate -- Polycarbonates -- Polymerization -- Cinnamoyl -- Coumarin -- Photo-crosslinking -- Dimerization; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; Polymerization; Polymers; Periodicals; Electronic journals; 547.705
• DOI: 10.1016/j.eurpolymj.2018.05.038
• Languages: English
• ISSNs: 0014-3057

Abstract

Graphical abstract: Highlights: Coumarin functionalized polymers crosslink faster than cinnamoyl ones at 365 nm. More coumarin functionalization causes quicker gelation and higher storage modulus. Rapid crosslink reversibility under 254 nm irradiation occurs in dilute solutions. Photo-dimerization kinetics are 3rd order and photo-cleavage kinetics are 2nd order. Abstract: Cinnamoyl and coumarin groups can be used to introduce photo-responsive behaviour to polymer systems, but they have never been directly compared within the same polymer system. Thus, this study examined cinnamoyl and coumarin functionalized aliphatic polycarbonate copolymers to determine their relative suitability for use as biomaterials. Coumarin functionalized polycarbonates photo-crosslinked significantly faster and resulted in networks with high crosslink density when irradiated with UVA radiation. Real-time tracking using rheometry showed that increasing the degree of coumarin functionalization on the aliphatic polycarbonate copolymers resulted in quicker gelation and higher final storage modulus. In addition, decreasing the UV intensity and increasing the sample thickness also increased the final storage modulus. Although no appreciable reversibility was detected for solvent-free or solvent-swelled crosslinked polymer networks, rapid reversibility upon exposure to 254 nm light was observed in dilute solutions. The kinetics of photo-dimerization were third order while the photo-cleavage reaction kinetics were second order with respect to the concentration of the photoactive group. Overall, the photo-reversible crosslinking of coumarin functionalized aliphatic polycarbonates was demonstrated. These polymers have potential for use in photo-crosslinking or photo-reversible biomaterials applications.