Natural-based polymers

Several review articles are available on the synthesis, physico-chemical properties, and bio degradability of natural-based polymers, and their composites [6-9]. The same aspects have been the subjects of recent books [10-12]. In the following account, we concentrate on organic esters of cellulose. 

Chitosan, a natural-based polymer obtained by alkaline deacetylation of chitin, is nontoxic, biocompatible, and biodegradable. These properties make chitosan a promising candidate for conventional and novel drug delivery systems. Because of the high affinity of chitosan for cell membranes, it has been used as a coating agent for liposome formulations [43-45]. 

R.L. Reis, N.M. Neves, Natural-Based Polymers for Biomedical Applications, CRC Press,... 

A. J. Domb, Polysaccharides as carriers of bioactive agents for medical applications, in Natural-Based Polymers for Biomedical Applications, Ed., R. L. Reis, Woodhead Publishing Ltd., Cambridge, (2008). 

Petzold G, Petzold-Welcke K, Qi H, Stengel K, Schwarz S, Heinze T (2012) Sticky removal with natural based polymers - highly cationic and hydrophobic types compared with unmodified ones. CarbohydrPolym 90 1712... 

Can be synthetic polymers or natural-based polymers XH = -OH or -NH2 Figure 4.12 Application of urethane/urea chemistry in polymer functionalization and cross-linking (a) introduction of functional groups using functionalized monoisocyanates (b) introduction of isocyanates as functional groups (c) application of urethane/urea reaction as a cross-linking method. 

Natural-based polymers for biomedical appUcations Edited by R. L. Reiss et al... 

Most natural-based polymers show a large water take up and high water permeability. They also change their mechanical and barrier properties in high moisture conditions, which is also a major disadvantage. This water sensitivity can develop a more spontaneous, non-controllable degradation under the influence of bacteria. 

Natural Based Polymers for Biomedical Applications (ISBN 9781845692643)... 

Reis, R.L., Neves, N.M., Mano, J.F., Gomes, M.E., Marques, A.P., and Azevedo, H.S. (2008) Natural-Based Polymers for Biomedical Applications, Woodhead Publishing Limited and Maney Publishing Limited, England. 

MAR Martins, M., Craveiro, R., Paiva, A., Duarte, A.R.C., and Reis, R.L., Supercritical fluid processing of natural based polymers doped with ionic liquids, Chem. Eng. J., 241, 122, 2014. 

In biopolymer-based films and coatings production, plasticizers are also essential additives since they can improve flexibility and handling of films, maintain integrity, and avoid pores and cracks in the polymeric matrix (Garcia et al., 2000]. The use of natural-based polymers films depends on several features including cost, availability, functional attributes, mechanical properties (strength and flexibility], optical quality (gloss and opacity], barrier requisites (water vapor, O2 and CO2 permeability], structure resistance to water and sensorial acceptance (Vieira et al., 2011]. 

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