Natural polymers synthesis

Technologies for the sustained manufacture of high polymers that reduce the burden on the natural environment are discussed. A review is included of high polymer synthesis using syngas and its derivatives that can be obtained through... 

New natural polymers based on synthesis from renewable resources, improved recyclability based on retrosynthesis to reusable precursors, and molecular suicide switches to initiate biodegradation on demand are the exciting areas in polymer science. In the area of biomolecular materials, new materials for implants with improved durability and biocompatibility, light-harvesting materials based on biomimicry of photosynthetic systems, and biosensors for analysis and artificial enzymes for bioremediation will present the breakthrough opportunities. Finally, in the field of electronics and photonics, the new challenges are molecular switches, transistors, and other electronic components molecular photoad-dressable memory devices and ferroelectrics and ferromagnets based on nonmetals. 

Besides the previously mentioned collagen, a wide variety of natural polymers have been involved in the synthesis of bio-nanohybrid materials with potential application in bone repair and dental prostheses. For instance, some recent examples refer to bionanocomposites based on the combination of HAP with alginate [96,97], chitosan [98,99], bovine serum albumin (BSA) [100], sodium caseinate [101], hyaluronic acid [102], silk fibroin [103,104], silk sericin [105], or polylactic add (PLA) [106,107]. These examples illustrate the increasing interest in the subject of HAP-based biohybrid materials, which has led to almost 400 articles appeared in scientific journals in 2006 alone. 

In his famous work of 1920 Hermann Staudinger first described the correct structure of polystyrene (10). It was Staudinger, too, who gave polystyrene its name and elucidated the mechanism of its formation (11). The polymerization of styrene provided access to a big class of substances and made a significant contribution to the understanding of natural polymers and to the synthesis of industrial plastics. A whole new branch of the chemical industry is based on the key substance polystyrene. 

A 100% natural polymer based entirely on agricultural products, the polyester elastomer obtained by reacting castor oil with a castor oil derivative, sebacic acid, was the basis for the synthesis of SIN s. 

It represents a delicate balance and interrelationship between feedstocks and so-called by-products from one reaction that become critical reactants in another reaction. Monomer and polymer synthesis continues to undergo change and improvement as the natural environment and societal and worker health continue to be dominant factors. 

Some natural polymers such as cotton, slik, and cellulose have the extended-chain morphology, but their morphologies are determined by enzymatically controlled synthesis and crystallization processes. Extended-chain morphology is obtained in some synthetic... 

The second group of saturated 5(47/)-oxazolones used as intermediates for polymer synthesis are the 2,2 -bis(oxazolones) with 2,2 -bis[4,4-dimethyl-5(47/)-oxazolone] 329 being the simplest member of the series (Fig. 7.33). These compounds, are prepared by cyclization of the corresponding bis(amino acids) and give a wide variety of polymers after ring opening with diamines, dialcohols or other nucleophiles. The physical chemical properties of these polymers depend on the nature of the substituents and the size of the chain. Some selected references describe representative examples. 

The mechanical synthesis of block and graft copolymers by vibromilling a polymer-monomer blend has been performed by many researchers. Natural polymers (14,17) vinyl polymers (18—27), and heterochain polymers (18, 28-34) have been formed during polymer mechanochemical degradation. Importantly, Simionescu, Vasiliu-Oprea and Neguleanu studied the possibility of carrying out mechanically-induced polycondensations starting from polyesters and diamines (33,35-37). 

Figure 28 shows the plastogram for an interstructural monomer (styrene). The mechanoehemical synthesis by mastication was also applied to natural polymers (80,82). The results are reported on Tables 19 and 20. 

Ethylene glycol in the presence of an acid catalyst readily reacts with aldehydes and ketones to form cyclic acetals and ketals (60). 1,3-Dioxolane [646-06-0] is the product of condensing formaldehyde and ethylene glycol. Applications for 1,3-dioxolane are as a solvent replacement for methylene chloride, 1,2-dichloroethane, 1,1,1-trichloroethane, and methyl ethyl ketone as a solvent for polymers as an inhibitor in 1,1,1-trichloroethane as a polymer or matrix interaction product for metal working and electroplating in lithium batteries and in the electronics industry (61). 1,3-Dioxolane can also be used in the formation of polyacetals, both for homopolymerization and as a comonomer with formaldehyde. Cyclic acetals and ketals are used as protecting groups for reaction-sensitive aldehydes and ketones in natural product synthesis and pharmaceuticals (62). 

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