Polysaccharides are complex but essential compounds utilized in many areas such as biomaterials, drug delivery, cosmetics, food chemistry or renewable energy. Modifications and functionalizations of such polymers are often necessary to achieve molecular structures of interest. In this area, the emergence of the "click" chemistry concept, and particularly the copper-catalyzed version of the Huisgen 1,3-dipolar cycloaddition reaction between terminal acetylenes and azides, had an impact on the polysaccharides chemistry. The present review summarizes the contribution of "click" chemistry in the world of polysaccharides.

International audienceCyclodextrins are important building blocks in organic chemistry. This review deals with the role of click chemistry in this family of cyclic oligosaccharides, focusing on the different areas of chemistry, including chromatography, biological applications, the elaboration of superstructures, and metal detection, that benefit from this reaction. In this paper, attention is given to organic modifications by using functionalizations such as azidation and propargylation and to click chemistry grafting onto the two faces of cyclodextrins. Research papers where cyclodextrins are not directly involved in a click chemistry reaction are not considered

A layer-by-layer (LbL) self-assembly technique using polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) was employed to build up polyelectrolyte multi-layers on pretreated thermomechanical pulp fibres. These pretreated fibres previously had been oxidized by means of a 4-acetamido TEMPO-mediated process in order to create carboxylic functions. These allow the subsequent formation of amide bonds between PAH and fibres. X-ray photo-electronic spectroscopy (XPS) analyses confirmed the formation of amide bonds between the carboxylic function on the fibres and the primary amine function of the PAH. Besides, the surface charge intensity of the coated fibres was determined by measuring the zeta potential after each treatment step.

The use of two polycarboxylic acids (PCAs), such as 1,2,3,4-butanetetracarboxylic acid (BTCA) and citric acid (CA), was employed to esterify handsheets prepared from thermomechanical pulp (TMP) fibers. Sodium hypophosphite was used as a catalyst. The Fourier transform infrared (FTIR) spectrometry technique was utilized to verify the ability of these PCAs to form ester functions between the fibers. The modifications of both the temperature and the mass amount of the PCA were investigated. Finally, the wet breaking length of the prefabricated and cured handsheets was measured and an improvement was observed in both cases. The raise of the mass amount increased the wet breaking length for the two cases. On the other hand, a comparison between the two PCAs was carried out. For the same mass amount, BTCA was more effective to cross-link the TMP fibers at high temperature while CA showed slightly better results at low temperature.

International audiencep-Toluenesulfonyl cellulose was prepared by reacting cellulose in aqueous medium, instead of via traditional routes, which involve the use of DMAc/LiCl, or more recently, ionic liquids. The influence of several parameters on the reaction efficiency has been studied; amount of tosylchloride, presence of triethylamine, reaction time and use of sodium hydroxide or sodium chloride. The resulting p-toluenesulfonyl cellulose samples were characterized by means of FTIR and NMR spectroscopy. The effects of solvent on the crystalline change during tosylation were investigated by X-ray diffraction (XRD). The degree of substitution (DS) was determined by 1H NMR and confirmed by X-ray photoelectron spectroscopy (XPS). Tosylcelluloses with DS from 0.1 to 1.7 have been prepared