Cohesive force change induced by polyperoxide degradation for application to dismantlable adhesion

Polyperoxides containing peroxy bonds as the main-chain repeating units are a new class of degradable polymers because of significant changes in their molecular weight and physical properties during a degradation process. In this study, the application of linear and network polyperoxides to dismantlable adhesion was investigated. When the linear polyperoxide obtained from methyl sorbate and oxygen (PP-MS) was used as a pressure-sensitive adhesive (PSA), its shear holding power and 180° peel strength immediately decreased upon heating at 70 °C or under UV irradiation. Low-molecular-weight products, which were generated by the degradation of PP-MS, behaved as a plasticizer to effectively reduce the cohesive force. The adhesive properties of two types of polyperoxides-based network polymers, the cross-linking point and main-chain degradable network polymers, were evaluated. A cross-linking point degradable network polymer was produced by the oxygen cross-linking of dienyl-functionalized poly(ethylene glycol). A main-chain degradable network polymer was formed by the diisocyanate cross-linking of a hydroxy-functionalized polyperoxide. Both network polymers showed a higher adhesive strength than PP-MS due to their three-dimensional network structure. Noteworthy, the adhesive strength of the main-chain degradable network polymer was varied from the level of PSA to structural adhesives by increasing the added amount of the diisocyanate cross-linker. After heating at 110 °C, the cohesive and adhesive strengths significantly decreased. The linear and network polyperoxides are shown to be promising materials for dismantlable adhesion.