Cellulosates, alkali metal polymerization

Recently, the methods of anionic graft polymerization of vinyl monomers have been adopted for graft pol3nnerization to cellulose, and a few papers have appeared in the literature.All of these involve the "grafting from" process. Alkali metal cellulosates are used as initiators for the anionic graft polymerization of vinyl monomers (Scheme 1). Although this method seems more versatile it does not allow adequate structural control, and it often yields rather polydisperse samples. 

The first attempts to produce a graft copolymer of poly(amino acids) onto the natural polymers, such as cellulose, starch, and their derivatives, were carried out by Zilka and Avny in 1965. Sodium methoxide was known to be an initiator of NCA polymerization. Therefore, they proposed to use alkoxide derivatives of polysaccharides as macroinitiators for the graft copolymerization of NCA s of a-amino acids. All known methods for production of alkoxide derivatives of natural polymers, such as the reaction of polyhydroxy polymers with sodium metal in liquid ammonia, or exchange reactions between lower alkoxides and polyhydroxy polymers, - were unsatisfactory for the subsequent graft copolymerization of NCAs, because any residual base would lead to homopolymerization. In addition, alkoxide derivatives of cellulose acetate and nitrocellulose could not be obtained by these conventional methods due to chemical degradation. Zilka et al., finally found that the reaction of alkali metal naphthalenes [20] with polyhydroxy polymers in either... 

Alkali is not capable of dissolving native cellulose. Only depolymerized cellulose fragments with a low degree of polymerization are alkali soluble. Certain quaternary ammonium compounds are more effective resulting in full solubility, A mixture of dimethyl sulfoxide and paraformaldehyde (DMSO-PF) has interesting properties as a cellulose solvent. However, its effect depends at least partly on the formation of a hydroxymethylcellulose derivative. The most important cellulose solvents are metal complexes of... 

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