Photocrosslinking of Polyacrylamides Using [2+2] Photodimerisation of Monothiomaleimides. Aljuaid, M., Houck, H. A., Efstathiou, S., Haddleton, D. M., & Wilson, P. MACROMOLECULES, 55(19):8495–8504, October, 2022.
doi  abstract   bibtex   
The [2 + 2] photocycloaddition of monothiomalei-mides (MTMs) has been exploited for the photocrosslinking of polyacrylamides. Polymer scaffolds composed of dimethylacryla-mide and varying amounts of D,L-homocysteine thiolactone acrylamide (5, 10, and 20 mol %) were synthesized via free-radical polymerization, whereby the latent thiol functionality was exploited to incorporate MTM motifs. Subsequent exposure to UV light (lambda = 365 nm, 15 mW cm-2) triggered intermolecular crosslinking via the photodimerization of MTM side chains, thus resulting in the formation of polyacrylamide gels. The polymer scaffolds were characterized using Fourier transform infrared spectroscopy, UV- visible spectroscopy, 1H NMR spectroscopy, and size exclusion chromatography, confirming the occurrence of the [2 + 2] photocycloaddition between the MTM moieties. The mechanical and physical properties of the resulting gels containing various MTM mol % were evaluated by rheology, compression testing, and swelling experiments. In addition, scanning electron microscopy was used to characterize the xerogel morphology of 5 and 10 mol % MTM hydro-and organo-gels. The macro-porous morphology obtained for the hydrogels was attributed to phase separation due to the difference in solubility of the PDMA modified with thiolactone side chains, provided that a more homogeneous morphology was obtained when the photo-gels were prepared in DMF as the solvent.
@article{aljuaid_photocrosslinking_2022,
	title = {Photocrosslinking of {Polyacrylamides} {Using} [2+2] {Photodimerisation} of {Monothiomaleimides}},
	volume = {55},
	issn = {0024-9297},
	doi = {10.1021/acs.macromol.2c01710},
	abstract = {The [2 + 2] photocycloaddition of monothiomalei-mides (MTMs) has been exploited for the photocrosslinking of polyacrylamides. Polymer scaffolds composed of dimethylacryla-mide and varying amounts of D,L-homocysteine thiolactone acrylamide (5, 10, and 20 mol \%) were synthesized via free-radical polymerization, whereby the latent thiol functionality was exploited to incorporate MTM motifs. Subsequent exposure to UV light (lambda = 365 nm, 15 mW cm-2) triggered intermolecular crosslinking via the photodimerization of MTM side chains, thus resulting in the formation of polyacrylamide gels. The polymer scaffolds were characterized using Fourier transform infrared spectroscopy, UV- visible spectroscopy, 1H NMR spectroscopy, and size exclusion chromatography, confirming the occurrence of the [2 + 2] photocycloaddition between the MTM moieties. The mechanical and physical properties of the resulting gels containing various MTM mol \% were evaluated by rheology, compression testing, and swelling experiments. In addition, scanning electron microscopy was used to characterize the xerogel morphology of 5 and 10 mol \% MTM hydro-and organo-gels. The macro-porous morphology obtained for the hydrogels was attributed to phase separation due to the difference in solubility of the PDMA modified with thiolactone side chains, provided that a more homogeneous morphology was obtained when the photo-gels were prepared in DMF as the solvent.},
	number = {19},
	urldate = {2022-10-24},
	journal = {MACROMOLECULES},
	author = {Aljuaid, Mohammed and Houck, Hannes A. and Efstathiou, Spyridon and Haddleton, David M. and Wilson, Paul},
	month = oct,
	year = {2022},
	pages = {8495--8504},
}

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