Cellulose polymers, advantages

Recently, a pH sensor developed by immobilizing a direct azo dye on a porous cellulosic polymer film has been described [37]. Advantageous features of the design include a rapid equilibration time (< 1.3 s) and a large dynamic range (>4 pH units with Congo Red as dye). 

The primary use of cellulose film has been for wrapping purposes. The past years have witnessed a renewed interest in cellulose research and application sparked mostly by technological interests in renewable raw materials and more environmentally-friendly and sustainable recourses. It has been estimated that the yearly biomass production of cellulose is 1.5 tons, making it an inexhaustible source of raw material for environmentally-friendly and biocompatible products [3]. Cellulose derivatives are used for coatings, laminates, optical films, pharmaceuticals, food, and textiles. Numerous new applications of cellulose take advantage of its biocompatibility and chirality for the immobilization of proteins and antibodies and for the separation of enantiometric molecules, as well as the formation of cellulose composite with synthetic polymers and biopolymers. This chapter basically discussed on the medical applications of cellulose. 

As for the solid support, several polymer-supported amines were tested (Fig. 2). For either the pyrazole and isoxazole synthesis, the best results were given by aniline-functionalized cellulose, which has also the advantage of a relatively low cost. For the 2-aminopyrimidine library, polystyrene-based piperazine and piperidine gave products with a much higher purity compared with other secondary non-cyclic or primary amines, hi both cases, the resins could be reused for up to four times before degradation in their behavior was observed. This reusability could be further enhanced (up to 10 cycles for cellulose-based aniline) when the microwave-assisted protocols were used. 

The membrane is critically important in osomometry. Selection of a membrane involves reconciliation of high permeability toward the solvent with virtual impermeability to the smallest polymer molecules present in the sample. Membranes of cellulose are most widely used. Commercially Regenerated cellulose film is a common source. The undried gel cellophane film is often preferred, but the dry film may be swollen in water (or in aqueous solutions of caustic or zinc chloride ) to satisfactory porosity. Useful cellulose membranes may also be prepared by denitration of nitrocellulose films/ and special advantages have been claimed for bacterial cellulose films. The water in the swollen membrane in any case may be replaced by a succession of miscible organic solvents ending with the one in which osmotic measurements are to be made. Membranes of varying porosity may be... 

The oldest method of resolving enantiomers by TLC takes advantage of the natural chiral properties of cellulose and triacetylcellulose resulting from the helical structure of the polymers (98). Amino acid derivatives have been resolved on silica gel layers impregnated with chiral acids or bases, for example. 

---