Synergistic toughening of silicon-containing arylacetylene resin via allyl bisimide blending

Abstract

Poly (silicon-containing arylacetylene)s (PSAs) resin exhibit excellent thermal properties, yet their application in advanced composites is hindered by inherent brittleness and poor interfacial adhesion with reinforcements. To address these challenges, this study introduces a modification strategy by blending PSA with 4.4′-diallyl oxybis (phthalimide) (PIO), designed to enhanced toughness while maintaining thermal resistance. The PIO was synthesized via a controlled reaction of 4.4′-Oxydiphthalic anhydride (ODPA) and allylamine, and its structure was characterized by ¹H NMR , FTIR and EI-MS. PSA/PIO hybrid resins (PSAIO) with varying PIO ratios (3-9 wt%) were prepared, and their rheological properties, curing behavior and thermal stability were systematically characterized. The modified resins retained processability with a slight increase in viscosity, while their curing mechanisms involved synergistic crosslinking between alkyne groups of PSA and allyl groups of PIO. Mechanical evaluations revealed that the flexural strength and interlaminar shear strength (ILSS) of quartz fiber/PSAIO composites (QF/PSAIO) increased by 54.4% and 74.2%, respectively, at 5 wt% PIO loading. At 7 wt% PIO loading, the mode II interlaminar fracture toughness (G_ⅡC) of QF/PSAIO7 was as high as 519.2 J/m², increasing by 113%. Despite a marginal reduction in thermal decomposition temperature (T_d5 > 500°C), the composites maintained excellent dielectric properties (ε = 3.31, tan δ = 2.86 × 10^-3) and high-temperature mechanical properties. This work establishes a scalable approach to balance thermomechanical performance in PSA-based composites, offering insights into interfacial optimization and crosslink density modulation for aerospace and electronics applications.