title: UV-Induced [2+2] Grafting-To Reactions for Polymer Modification of Cellulose.
abstract: Benzaldehyde-functional cellulose paper sheets have been synthesized via tosylation of cellulose (Whatman No 5) followed by addition of p-hydroxy benzaldehyde. Via UV-induced Paterno-Büchi [2+2] cycloaddition reactions, these aldehyde functional surfaces are grafted with triallylcyanurate, trimethylolpropane allyl ether, and vinyl chloroacetate. In the following, allyl-functional polymers (poly(butyl acrylate), pBA, Mn = 6990 g mol(-1) , Đ = 1.12 and poly(N-isopropyl acrylamide), pNIPAAm, Mn = 9500 g mol(-1) , Đ = 1.16) synthesized via reversible addition fragmentation chain transfer polymerization are conjugated to the celloluse surface in a UV-induced grafting-to approach. With pBA, hydrophobic cellulose sheets are obtained (water contact angle 116°), while grafting of pNIPAAm allows for generation of "smart" surfaces, which are hydrophilic at room temperature, but that become hydrophobic when heated above the characteristic lower critical solution temperature (93° contact angle). The Paterno-Büchi reaction has been shown to be a versatile synthetic tool that also performs well in grafting-to approaches whereby its overall performance seems to be close to that of radical thiol-ene reactions.
authors.affiliation: Polymer Reaction Design Group, Institute for Materials Research (IMO), Universiteit Hasselt, Martelarenlaan 42, 3590, Diepenbeek, Belgium.
authors.forename: Matthias
authors.initials: M
authors.lastname: Conradi
authors.affiliation: Polymer Reaction Design Group, Institute for Materials Research (IMO), Universiteit Hasselt, Martelarenlaan 42, 3590, Diepenbeek, Belgium.
authors.forename: Gijs
authors.initials: G
authors.lastname: Ramakers
authors.affiliation: Polymer Reaction Design Group, Institute for Materials Research (IMO), Universiteit Hasselt, Martelarenlaan 42, 3590, Diepenbeek, Belgium.|IMEC associated lab IMOMEC, Wetenschapspark 1, 3590, Diepenbeek, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Junkers
mesh_terms: D000179:Acrylates / Q000737:chemistry; D000180:Acrylic Resins / Q000737:chemistry; D001547:Benzaldehydes / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D061565:Cycloaddition Reaction; D057927:Hydrophobic and Hydrophilic Interactions; D010209:Paper; D058105:Polymerization / Q000528:radiation effects; D011409:Propylene Glycols / Q000737:chemistry; D013499:Surface Properties; D014227:Triazines / Q000737:chemistry; D014466:Ultraviolet Rays; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D000179:Acrylates; D000180:Acrylic Resins; D001547:Benzaldehydes; D011409:Propylene Glycols; D014227:Triazines; D014753:Vinyl Compounds; C480124:1,3,5-triallyl isocyanurate; C052970:poly-N-isopropylacrylamide; D002482:Cellulose
keywords: [2+2] cycloaddition; cellulose; photoreactions; surface modifications; thermoresponsive materials