Isotropic and anisotropic interphases in polymer systems

A polyisoprene-poly 4-vinyl pyridine (PIP/P4VP) diblock polymer has been used as adsorbate and adhesive on PVC and PMMA substrates. The diblock polymer is able to undergo surface restructuring, the rubber constituent being preferentially surface localized during contact with non-polar media, the P4VP moiety becoming dominant when in contact with polar media. Acid-base characterization shows that specific acid-base interaction takes place in the PVC-PIP/P4VP pairing, but not in the PMMA case. The block copolymer chain configuration on PVC is independent of the adsorbed layer thickness, creating an isotropic interphase. Adsorbed on PMMA, the copolymer chain undergoes a configurational change, creating an anisotropic interphase. Bond strength data indicate that the presence of acid-base interactions and of isotropic interphases is beneficial to both the initial value and to the retention of bond characteristics during accelerated aging.