Pressure sensitive adhesives based on interpolymer complexes

Abstract

Adhesion of noncovalent complexes formed between complementary polymers bearing functional groups capable of hydrogen bonding or ionic interactions is reviewed. The rational design of novel adhesive materials with tailored properties requires a molecular insight into the mechanism of their self-assembly. At the most fundamental molecular level, strong adhesion is the result of a delicate balance between two generally conflicting properties: high energy of intermolecular cohesion and large free volume. These conflicting properties can be achieved in self-assembling interpolymer complexes. The adhesive and mechanical properties of the polymer blends can easily be controlled by blend composition and the type of intermolecular bonding (hydrogen bonding or ionic interactions or combination of both), whereas their solubility and water absorbing capacity are dictated by the hydrophilicity of the parent components. Innovative self-adhering pressure sensitive adhesives are based either on nonstoichiometric interpolymer complexes or on stoichiometric complexes of long-chain polymers with telechelic oligomers. Once the molecular mechanism of self-assembly of adhesive materials has been established, the molecular design of new adhesives with tailored properties becomes feasible. The number of functional polymers suitable to serve as parent components for producing novel adhesives is very large, suggesting that the polymer blending approach, based on molecular design considerations, may revolutionize the adhesive industry in the coming decades.