High-Impact Epoxy Resins with Superior Hydrophobicity Toughened by Epoxy Functionalized Poly(olefin-alt-maleimide) Derivatives

The inherent disadvantages of low toughness and high brittleness severely limit the widespread applications of epoxy resins (EPs), and it is highly desirable to toughen EPs while maintaining their rigidity and thermal properties. Herein, a type of epoxy functionalized poly[1-hexene-alt-N-(2-methoxymethyl oxirane)maleimide] (PHMIEP) was specially designed and synthesized by the self-stabilized precipitation polymerization (2SP) of 1-hexene and maleic anhydride, followed by imidization, hydroxymethylation, and epoxidation. Due to the presence of both rigid cyclic maleimide units and flexible pendant butyl groups, epoxy functionalized PHMIEP can serve as an effective toughening modifier for EPs. With 4,4-diaminodiphenylmethane as the curing agent, the EPs with 5 phr PHMIEP showed a record-high impact strength and tensile strength of 54.04 kJ/m2 and 95.84 MPa, which were 121 and 23% higher than the neat EPs, respectively. Moreover, the PHMIEP-modified EPs exhibited similar thermal stability and glass-transition temperature to those of the neat EPs. More impressively, the resultant EPs showed superior hydrophobicity in comparison to the unmodified EPs due to the incorporation of hydrophobic imide and alkyl segments. Furthermore, in order to reduce the preparation cost, complex olefinic mixtures derived from the cracking product of raffinate oil were used directly to replace 1-hexene. The EPs modified with poly[cracked raffinate oil-alt-N-(2-methoxymethyl oxirane)maleimide] (PRMIEP) also showed excellent comprehensive properties. Due to the highly enhanced toughness, higher strength, and comparable thermal stability, the PHMIEP/PRMIEP-toughened EPs demonstrate great potential as a high-performance resin matrix for application in the fields of electronic packaging, coating, and engineering plastics.