Heat-Resistant Polymer Networks Prepared from Processable Resveratrol-Based Propargyl Ether Monomers

Three propargyl ether thermosetting resins were prepared from biosynthetic trans-resveratrol (1), cis-resveratrol (2), and dihydroresveratrol (3). The cure chemistry of the monomers as well as the thermal stability and mechanical properties of cross linked networks were then characterized by techniques including differential scanning calorimetry, thermal gravimetric analysis, and dynamic mechanical analysis. The monomers were highly processable, existing as low melting solids (1, Tm = 81 degrees C; 3, supercooled liquid with an ultimate Tm = 40 degrees C), or a permanent room-temperature liquid (2). All three resins exhibited broad processing windows and high degrees of cure ranging from 97-99%. The glass transition temperatures (Tg) of 1 and 2 were 389 and 384 degrees C (loss modulus), respectively, while 3 did not exhibit a well-defined Tg. All three of the networks exhibited outstanding thermal stability with char yields of 66, 64, and 54% at 1000 degrees C (under N2) for 1, 2, and 3, respectively. Heat release capacities of 1, 2, and 3 were 53, 41, and 114 J g-1K-1, respectively, consistent with self-extinguishing (3) or non-ignitable (1, 2) polymers. The networks also exhibited low water uptakes ranging from 3.64 to 1.59 wt %. The thermal stability, fire-resistance, and mechanical properties of the resveratrol-based resins represent significant improvements over monomers derived from conventional petroleum-based bisphenols (e.g., bisphenol A). This work demonstrates that the unique morphology afforded by bio-based monomers allows for the preparation of polymer networks with enhanced properties. The resveratrol networks have potential applications as components of high-temperature and fire-resistant composite materials for aerospace applications.