Polymer such as rubber, suberin, melanin and lignin. Naturally occurring polymers such as cotton, starch and rubber were familiar materials for years before synthetic polymers such as polyethene and perspex appeared on the market. Many commercially important polymers are synthesized by chemical modification of naturally occurring polymers. Prominent examples include the reaction of nitric acid and cellulose to form nitrocellulose and the formation of vulcanized rubber by heating natural rubber in the presence of sulfur. Ways in which polymers can be modified include oxidation, cross-linking and endcapping. Especially in the production of polymers the gas separation by membranes has acquired increasing
Molecularly imprinted polymer Molecularly imprinted polymer A molecularly imprinted polymer (MIP) is a polymer that has been processed using the molecular imprinting technique which leaves cavities in the polymer matrix with an affinity for a chosen "template" molecule. The process usually involves initiating the polymerization of monomers in the presence of a template molecule that is extracted afterwards, leaving behind complementary cavities. These polymers have affinity for the original molecule and have been used in applications such as chemical separations, catalysis, or molecular sensors. Published works on the topic date to the 1930s. Molecular imprinting is the process of generating an impression within