The Chemical Modification of Polymers

In the early days of polymer chemistry and technology, a new chemical modification successfully applied to one polymer was quickly evaluated with a 

The Science and Technology of Rubber. http //dx.doLor l0.1016/B978-0-12 5945 4 6.00011-X 

2 CHEMICAL MODIFICATION OF POLYMERS WITHIN BACKBONE AND CHAIN ENDS 

Polymer properties are dependent on many factors, including chain end interactions with substrates such as carbon black or silica fillers, as well as clay and calcium carbonate. At this point, there is a large volume of work that has been done on chain end modification, particularly those made by anionic polymerization with group 1 or group II metals (Bielinsk et al., 1995 Yamato and Oahu, 1996 Schulz et al., 1974), as seen later. 

This approach was made possible via the reaction of metallic chain ends with active metal halide as shown on the following page, such as tin tetrachloride and silica terachlorides. These types of reactions led to increased molecular weight as well as improvements in polymer filler interactions that result in improved properties of the polymers (Urneck and Short, 1970). 

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Reactive extrusion is the chemical modification of polymer while it is being transported in an extruder. In this work, polypropylene is intentionally degraded by the addition of a free radical initiator (a peroxide) during extrusion. The product has improved flow properties because of the removal of the high molecular weight tail and the narrowing of the molecular weight distribution. 

The chemical modification of polymers is a post polymerization process which is used in certain situations i) to improve and optimize the chemical and mechanical properties of existing polymers or ii) to introduce desirable functional groups in a polymer. 

Ceresa, R. J., The Chemical Modification of Polymers, Chap. 11 in Science and Technology of Rubber,... 

The chemical modification of polymers with a view to confer them new properties presents a great interest. In this area, the activation of natural or synthetic polymers by ozone followed in a second step by grafting of monomers or reactive molecules in radical medium constitutes a field of important developments, mainly in terms of patents. We will give here the main outlines. 

Mechanochemical processing has been used to conduct the esterification of poly(vinyl alcohol) (PVA) with maleic anhydride through stress-induced reaction by pan-milling (Scheme 8.5). In comparison with conventional methods for the esterification of PVA, this protocol is viable and environmentally friendly and can be an effective technique for the chemical modification of polymers. ... 

Few papers on the chemical modification of polymers in supercritical CO2 have been published so far. In this short review we will mention the work on C02-as-sisted blending of polymers only very briefly. In the first place, this technique does not always imply a chemical modification of the supercritical carbon dioxide-swollen host polymer in which the monomer of the second blend component is polymerized, but, depending on the chosen polymerization conditions. 

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