Natural monomers

High-Performance and Functional Materials from Natural Monomers and Polymers... 

Biomass is a relatively inexpensive raw material. Since it is made by nature there is an enormous saving of energy. The main research areas include (1) isolation and purification of natural monomers and polymers, (2) modification of natural monomers and polymers, and... 

There is a good amount of data on the transformations of natural polymers, but the literature concerning chemical modifications of natural monomers is rather scanty. However, there are a few natural monomers that have found applications. The monomers in these cases are either modified into other suitable monomers of industrial importance or are polymerized directly into polymers. A few examples are given below for illustration. 

Furfural is a natural monomer obtained by the steam acid digestion of corncobs, bagasse, rice husks, oat hulls, or similar materials. It acts as the precursor for the preparation of two important monomers (Scheme 1), adipic acid and hexamethylene diamine, used in the... 

Terpene monomers are another class of interesting natural monomers because they give, on polymerization, hydrocarbon therplastic resins that exhibit a high degree of tackiness useful in pressure sensitive tapes [25]. They are also used for sizing paper and textile materials. Terpene-phenol resins are effective heat stabilizers for high-density polyethylene. 

Natural Monomer Already Polymerized Natural Monomer Not Yet Polymerized ... 

There exists a large number of natural monomers that needs further studies for their exploitation Pillai and Manjula have reviewed [25] the subject and a comprehensive list of potential monomers and their source is given in Table 18. 

Natural monomers and polymers present a scenario where they have a structural diversity and complexity that, with appropriate chemical modifications, and taking information from modern techniques of molecular and process designs could be utilized for transforming them into high-value polymers. This was exemplified by showing the example of a natural monomer, cardanol. 

Owing to their liquid or semisolid nature, monomers are easy to process into polymers. For radical polymerization the use of solid AIBN for liquid monomers at room temperature and liquid MEKP for semisolid monomers or a mixture of liquid and semisolid monomers with some heating is convenient. During the course of curing at 85- 100°C for 22 h the problem of surface inhibition of free radicals by oxygen from the air can be avoided by inert-gas blanketing. 

However, normally, the groups of both types are present in synthetic and natural monomer units of water-soluble polymers (Scheme 2), which suggests that the units are amphiphilic rather than hydrophobic or hydrophilic. Vasilevskaya et al. [22,23] reported a dumbbell model of the monomer unit in a chain in which a new representation of monomer units was proposed. In this representation, the amphiphilic character of the monomer units was... 

Although most of our polymers come from petroleum, an increasing number are being prepared from natural monomers, a trend that will surely continue. The application of biotechnology to the synthesis of these mono- /... 

Sorbitol is an interesting natural monomer obtained from glucose (sugar waste is used for this purpose) by dehydrogenation. It easily dehydrogenates into isosor-bide which is useful as a polyol for production of polymers/polyurethane [69, 70]. 

Natural monomers and polymers have complex structure and properties, which with proper modifications could be a substitute for today s high-performance plastic materials. Existing biodegradable polymers can be blended with different materials with the aim to reduce cost and to tailor the product for specific applications. NR and almost all other natural resources are discussed and possible modifications and the applications of these natural polymers as well as polymers from natural monomers are analyzed in this review. Further studies are required to improve the performance of these materials so that synthetic polymeric materials can be replaced by polymers derived from these renewable materials. 

It can be concluded that the advent of both free radical and cationic living polymerizations has brought new life into the area of terpene polymers and copolymers. No study is however known to the author regarding the use of enzymes to induce the polymerization of these natural monomers and such an... 

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