Hydrogen‐Bond‐Induced Interpenetrating‐Network Acrylic‐Modified Phenolic Resin and Its Synergistic Strengthening and Toughening

ABSTRACT

The application of phenolic resin (PF) is limited by its brittleness and poor toughness, making modification with flexible acrylic resin an important strategy. In this study, an acrylic resin was designed and synthesized via solution polymerization, then introduced into PF through reactive blending. The effect of acrylic resin content on material structure and properties was systematically investigated. Results show that the acrylic resin was successfully incorporated into the PF matrix. Hydrogen bonding enhanced the interfacial compatibility, and the combined Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical‐property results suggest the presence of an interpenetrating‐network‐like structure under appropriate conditions. With increasing acrylic resin content, system viscosity increased, pH decreased from 7.8 to 6.5, and water contact angle increased from 63° to 95.73°, indicating a transition from hydrophilic to hydrophobic surface, while the material remained amorphous. Optimal fracture strength and elongation at break reached 48.32 MPa and 29.36%, improvements of 182.6% and 236.3% over neat PF. The fracture surface showed a uniform microporous and bicontinuous phase structure, with failure evolving from brittle to ductile fracture. Meanwhile, the modified materials retained excellent thermal resistance without affecting the curing behavior. By harnessing the synergistic effects of hydrogen bonding and the interpenetrating‐network‐like structure, this modification successfully achieved simultaneous enhancement of strength and toughness in phenolic resin, offering a new perspective to overcome its inherent brittleness and broaden its applications.