Ring-Opening MetathesisPolymerization of TricyclicOxanorbornene Derivatives Enables Partially Renewable Comb-like Polymersas Phase Change Materials and Hot-Melt Adhesives

In spite of the remarkable success in the preparation of comb-like polymers, their practical applications are yet to be fully exploited. Herein, partially renewable comb-like polymers were efficiently synthesized via grafting-through strategy, and the potential applications of these materials as phase change materials and hot-melt adhesives were preliminarily explored. At first, ring-opening metathesis polymerization (ROMP) of various tricyclic oxanorbornene derivatives readily furnished comb-like polymers <b>P1</b>–<b>P6</b> featuring rigid backbone and flexible yet crystalline side chains. An enhancement in crystallinity is observed while prolonging the chain length of the pendant alkyl groups of these specimens. The ordered arrangement of aliphatic side chains derived from the van der Waals interaction is verified by wide-angle X-ray diffraction (WAXD) patterns of these polymers. Furthermore, <b>P1</b>–<b>P6</b> films show mechanical robustness and reprocessability, and their strength and toughness are discovered to be individually governed by the rigidity of the polymer backbone and the stiffness of pendant groups, respectively. As for thermal energy storage/release properties, the <b>P6</b> film exclusively displays a unique insulation property and excellent thermal durability such as shape stability, structural integrity, and highly reliable heat storage capability during a 500 times thermal cycling test. Meanwhile, the adhesion property of these comb-like polymers is estimated to be appreciably influenced by the molar fraction of the molten state. Thus, polymer <b>P3</b>, the specimen possessing the utmost chain length of amorphous side chains, exhibits optimal adhesive performance with anticorrosiveness and reusable characteristics.