Polyacetals, biodegradation

Heteroatom Chain Backbone Polymers. This class of polymers includes polyesters, which have been widely studied from the initial period of research on biodegradable polymers, polyamides, polyethers, polyacetals, and other condensation polymers. Their linkages are quite frequendy found in nature and these polymers are more likely to biodegrade than hydrocarbon-based polymers. 

Similar polyacetals were prepared by BASF scientists from CO-aldehydic aUphatic carboxyUc acids (189,190) and by the addition of poly(hydroxycarboxyhc acid)s such as tartaric acid to divinyl ethers (191) as biodegradable detergent polymers. 

Poiyacids, based on anionicaiiy polymerized giyoxyiic esters were cleverly developed by Monsanto and the work published in a series of patents(49) and papers(50,51). The polymers are polyacetals, stable in alkali, but not in acid hence, in use as detergents, they are stable, but hydrolyze as the pH falls to 7 in the sewer systems, after use, to biodegradable monomer. 

T.Ochi, Y. Maeda, and H. Ohme, Polymer alloy fibers with good biodegradability and abrasion resistance consisting of blends comprising polydactic acid) and polyacetals, Japanese patent JP 2003227037 A2, assigned to Toray Industries, Inc., Japan, August 15, 2003. 

Polyamides (Nylons) Fluorocarbon Polymers Rubbers Polyurethanes Polyacetal, Polysulfone, and Polycarbonate Biodegradable Polymers... 

Figure 1.24. Basic structures of polymer drug carriers with biodegradable polymer backbone poly[N -(2-hydroxyethyl)-L-glutamine] (a), poly(amido amine)s (b) and polyacetals (c).

There are many polymers that are suitable for the production of nanoparticles employed for drug delivery, which can generally be divided into two groups natural polymers, e.g., polysaccharides (chitosan), proteins (albumin, gelatin), as well as synthetic polymers, e.g., polyesters (poly(lactic add), poly(glycolic add), poly(hydroxy butyrate), poly-e-caprolactone, poly-p-malic add, poly(dioxanones)) polyanhydrides (poly(adipic add)) polyamides (poly(amino acids)) phosphorous-based polymers (polyphosphate) poly(cyano acrylates) polyurethanes polyortho esters and polyacetals. Extreme attention has to be paid to the biodegradability and biocompatibility of the polymers. It is essential that polymers used for medical applications are not detrimental for the tissue or cells and that they can be easily decomposed into simple harmless molecules and eliminated by the human body [ 18-22]. 

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