Modification of cellulose powder surface by grafting of polymers with controlled molecular weight and narrow molecular weight distribution

Abstract

ABSTRACT:To modify cellulose powder surface, the grafting of polymers with controlled molecular weight and narrow molecular weight distribution onto the surface by the termination of living polymer cation with amino groups introduced onto cellulose powder surface was investigated. The introduction of amino groups onto cellulose powder surface was achieved by the treatment of cellulose powder with isatoic anhydride. It was found that cellulose powder having amino groups are readily reacted with living poly(2-methyl-2-oxazoline) (polyMeOZO) cation, which was generated by ringopening polymerization with methyl p-toluenesulfonate as an initiator, and polyMeOZO with controlled molecular weight and narrow molecular weight distribution was grafted onto the surface. By the termination of living poly(isobutyl vinyl ether) (polyIBVE), which was generated by the polymerization with HCl/ZnCl 2 initiating system, with amino groups on cellulose powder, polyIBVE was also grafted onto the surface. The mole number of grafted polymer chain on cellulose powder surfaces decreased with increasing molecular weight of the living polymer cation, because of increasing steric hindrance with increasing molecular weight of living polymer cation. Wettability of cellulose powder surface to water was found to be controlled by grafting of hydrophilic or hydrophobic polymer onto the surface.

Controlled grafting of cellulose diacetate

“…For instance, monodisperse carboxy-functionalized polystyrene, prepared by anionic polymerization, was transferred to acyl halide and reacted with the residual hydroxyl groups of cellulose acetate [10]. Further, cationically prepared 'living' poly(2-methyl-2-oxazoline) or poly(isobutyl vinyl ether) were terminated with cellulose, into which amino groups were introduced [11]; also here, more or less uniform grafts were obtained. In addition to the vinyl monomers, also heterocycles, such as lactones, can be surface grafted from cellulose or its derivatives by ring-opening polymerization (ROP), giving in principle biodegradable polymeric materials [12][13][14].…”

Grafting from ramie fiber with poly(MMA) or poly(MA) via reversible addition-fragmentation chain transfer polymerization

“…However, the property of high water absorption of hydrophilic cellulose fibers limits large-scale applications of them due to the formation of weak interaction between natural fibers and polymers (Mohanty et al 2001). Thus, great efforts have been devoted to the development of new processes and efficient ways to improve the compatibility with synthetic polymers matrix, and to reduce the hydrophilicity of natural fibers through the chemical grafting modification of the cellulosic surface with hydrophobic monomers such as methyl methacrylate, styrene, isobutyl vinyl ether (Tsubokawa et al 2000).…”

Mechanism and Kinetics

“…An obvious means of achieving grafted polymerization by cationic mechanisms is to use a polymer backbone with functionalities, which can readily be converted to carbocations. Another is to employ a " grafting to " mechanism where functionalities on the backbone can combine with polymer carbocations to generate a covalent bond (e.g., the grafting of poly(butyl vinyl ether) onto aminated cellulose [14] ).…”