Adhesive synthetic basis

Emulsion polymerization is the basis of many industrial processes, and the production volume of latex technologies is continually expanding—a consequence of the many environmental, economic, health, and safety benefits the process has over solvent-based processes. A wide range of products are synthesized by emulsion polymerization, including commodity polymers, such as polystyrene, poly(acrylates), poly (methyl methacrylate), neoprene or poly(chloroprene), poly(tetrafluoroethylene), and styrene-butadiene rubber (SBR). The applications include manufacture of coatings, paints, adhesives, synthetic leather, paper coatings, wet suits, natural rubber substitutes, supports for latex-based antibody diagnostic kits, etc. ... 

Other polymers used in the PSA industry include synthetic polyisoprenes and polybutadienes, styrene-butadiene rubbers, butadiene-acrylonitrile rubbers, polychloroprenes, and some polyisobutylenes. With the exception of pure polyisobutylenes, these polymer backbones retain some unsaturation, which makes them susceptible to oxidation and UV degradation. The rubbers require compounding with tackifiers and, if desired, plasticizers or oils to make them tacky. To improve performance and to make them more processible, diene-based polymers are typically compounded with additional stabilizers, chemical crosslinkers, and solvents for coating. Emulsion polymerized styrene butadiene rubbers (SBRs) are a common basis for PSA formulation [121]. The tackified SBR PSAs show improved cohesive strength as the Mooney viscosity and percent bound styrene in the rubber increases. The peel performance typically is best with 24—40% bound styrene in the rubber. To increase adhesion to polar surfaces, carboxylated SBRs have been used for PSA formulation. Blends of SBR and natural rubber are commonly used to improve long-term stability of the adhesives. 

Other putative laminin-binding proteins have been described from a number of sources (for example, Smalheiser and Schwartz, 1987). Kleinman et al. (1991) used a synthetic peptide derived from the a chain of laminin to elute a 110 kDa protein from brain tissue however, the resulting molecule had sequence similarity to nucleolin. This putative receptor appears to be expressed in postnatal brain, particularly the hippocampus (Luckinbilledds et al., 1995). Albini et al. (1992) have described the isolation of a similar 100 kDa molecule from Y-79 retinoblastoma cells that is eluted from laminin affinity columns by 20 mM EDTA this binding protein has only intermediate affinity for laminin, however, but may act to influence gene expression independent of attachment. Laminin has been reported to bind to Ng-CAM on the basis of antibody inhibition studies, an interaction important for the formation of neuron-glia adhesion (Grumet etal., 1993). 

Polymers play a significant part in humans existence. They have a role in every aspect of modem life, such as health care, food, information technology, transportation, energy industries, and so on. The speed of developments within the polymer sector is phenomenal and, at same time, cmcial to meet the demands of today s and future life. Specific applications for polymers range from adhesives, coatings, painting, foams and packaging to stmctural materials, composites, textiles, electronic and optical devices, biomaterials, and many other uses in industries and daily life. Polymers are the basis of natural and synthetic materials. They are macromolecules and, in nature, are the raw material for proteins and nucleic acids, which are essential for human bodies. 

Nylons are synthetic thermoplastic polyamides of relatively high molecular weight that have been used as the basis for several types of adhesive systems. They are used as solution adhesives, as hot-melt adhesives, and as components of other adhesive-alloy types (nylon-epoxy and phenolic-nylon). The high-molecular-weight products are generally referred to as modified nylons. Low- and intermediate-molecular-weight materials are also available. The latter two are more commonly used in hot-melt formulations and the modified nylons are often blended with small amounts of a phenolic resin to improve surface wetting (hence nylon-phenolic). 

There are several polymers that form the basis of adhesives, and which are made by free radical chain polymerization. These include the carbon-chain synthetic rubbers. Acrylic adhesives. Ethylene vinyl acetate copolymers and polymer lattices. 

According to the European Pharmacopoeia cutaneous patches are flexible preparations containing 1 or more active substances. They are intended to be applied to the skin. They are designed to maintain the active substance(s) in close contact with the skin such that these may act locally . Cutaneous patches consist of an adhesive basis spread as a uniform layer on an appropriate support made of natural or synthetic material. The adhesive basis is not irritant or sensitising to the skin. The adhesive layer is covered by a suitable protective liner, which is removed before applying the patch to the skin. 

---