Cellulosic surfaces endowed with chemical reactivity by physical adsorption of functionalized polysaccharides

A strategy to functionalize cellulosic surfaces through physical adsorption of xyloglucan (XG) and carboxymethyl cellulose (CMC) derivatives bearing allyl or alkyne groups is reported. A set of functional polymer derivatives with degrees of substitution -DS- ranging from 0.10 up to 0.44 are first prepared through the opening of the epoxide ring of allyl glycidyl ether or propargyl glycidyl ether under mild basic aqueous medium. Contrary to alkyne-functionalized polymers, the radical copolymerization of allyl-XG and -CMC derivatives with acrylamide/acrylic acid leads to the formation of hydrogels, confirming their reactivity. The quantitative analysis of the deposition of these functionalized polysaccharides onto Whatman paper and wood pine fibers (spraying of aqueous solutions, drying and desorption step in water) shows that the physisorption of the polymer chains is not altered neither by the extent of the modification nor by the nature of the substituents. QCM-D experiments highlight a high affinity of allyl-XG for cellulosic substrates. The topochemical mapping by confocal Raman microscopy of cellulosic substrates on which alkyne polysaccharide derivatives have been deposited underpins that the surface coverage is rather uniform and that the diffusion of the polymer chains into the substrate reaches 40 μm. This aqueous functionalization/spraying procedure appears as a promising approach to confer novel adjustable surface properties to various cellulosic substrates, in a sustainable manner.