Study on the phthalonitrile cured via bio-tyrosine cyclic peptide: Achieving good thermal properties under low post-curing temperature

Tyrosine derived cyclic peptide (TCP) was employed to promote the curing reaction of a phthalonitrile monomer 1,3-bis(3,4-dicyanophenoxy) (3BOCN). Differential scanning calorimetry (DSC) and rheological analysis were used to study the curing behaviors of the TCP/3BOCN blend and confirmed a relatively high curing efficiency. Fourier transform infrared spectrometer (FT-IR) and two-dimensional infrared vibrational echo spectroscopy suggested the cyclic peptide reactive site was responsible for the unique curing behavior. Isoindolin, phthalocyanine and triazine were confirmed as curing products. Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) were used to measure the thermal and thermomechanical properties of the cured resin. The results firstly revealed the excellent thermal stability and high glass transition temperature (Tg) of this resin even under a moderate post-curing condition.