Synthesis of Biodegradable Water-Soluble Polymers

In many of the examples to be considered in this chapter, the reader is warned that often results claimed by the original authors are not always substantiated due to difficulty in estimating test reliability. However, the references are included as the polymers are often anticipated to be biodegradable to some extent and hence are a good indicator for future research directions and opportunities. 

All natural polymers are considered to be biodegradable or at least not harmful to the environment. However, modification of natural polymers either by grafting synthetic polymers or by chemical conversions such as oxidation and esterification, changes their properties and biodegradation characteristics significantly. Therefore, polymers produced by any of these modifications must be evaluated for biodegradability in the same manner as purely synthetic polymers. 

The biodegradability of functional derivatives of polyethylene, particularly polyvinyl alcohol and polyacrylic acid and derivatives have received attention because of their water solubility, high-volume use, and disposal into the aqueous environment. Polyvinyl alcohol is used in a wide variety of applications, including textiles, paper, plastic films, and temporary packaging, and polyacrylic acid is widely used in detergents as a builder, super absorbent for diapers and feminine hygiene products, water treatment, thickeners, pigment dispersant, and the like. 

Reaction time (h) Oxygen Consumed ( xM) Hydrogen Peroxide ( xM) Ketones ( xM) Carboxylic Acids (irM) 

Other bacterial strains identified as biodegrading polyvinyl alcohol include Flavobacterium [50], Acinetobacter [51], and many others as well as fungi, molds, and yeasts [52], Industrial evaluations at DuPont [53] and Air Products [54] indicate that over 90% of polyvinyl alcohol entering wastewater treatment plants is removed in those locations and hence no environmental pollution is likely. 

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SYNTHESIS OF BIODEGRADABLE WATER-SOLUBLE POLYMERS 505 Table 12.2 Photodegradation of Photo/Biodegradable Carboxylates... 

Nokwequ, G. M. and Bariyanga, J. Synthesis, characterization and biodegradability of a water-soluble poly(ethylene oxide) derivative polymer bearing carboxylic acid side chain function.. Bioact. Compat. Polym., 15, 503, 2000. 

This book covers both fundamental and applied research associated with polymer-based nanocomposites, and presents possible directions for further development of high performanee nanocomposites. It has two main parts. Part I has 12 chapters which are entirely dedicated to those polymer nanocomposites containing layered silicates (clay) as an additive. Many thermoplastics, thermosets, and elastomers are included, such as polyamide (Chapter 1), polypropylene (Chapter 4), polystyrene (Chapter 5), poly(butylene terephthalate) (Chapter 9), poly(ethyl acrylate) (Chapter 6), epoxy resin (Chapter 2), biodegradable polymers (Chapter 3), water soluble polymers (Chapter 8), acrylate photopolymers (Chapter 7) and rubbers (Chapter 12). In addition to synthesis and structural characterisation of polymer/clay nanocomposites, their unique physical properties like flame retardancy (Chapter 10) and gas/liquid barrier (Chapter 11) properties are also discussed. Furthermore, the crystallisation behaviour of polymer/clay nanocomposites and the significance of chemical compatibility between a polymer and clay in affecting clay dispersion are also considered. 

Similar structures were later employed to create original dendronized polymers 485 and 486, based on a chitosan backbone and using such sialodendrons as 484 (Fig. 50).328 Chitosan itself is nontoxic, biodegradable, and has widespread biological activities, but major intrinsic drawbacks such as low solubility in both organic solvents and water have hampered its development as a bioactive polymer. Thus, the synthesis of water-soluble... 

A. Breitenbach and T. Kissel, Biodegradable comb polyesters Part 1 synthesis, characterization and structural analysis of poly (lactide) and poly (lactide-co-glycolide) grafted onto water-soluble poly (vinylalcohol) as backbone. Polymer, 39(14), 3261-3271 (1998). 

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