Exploring the impact of novel ionic liquid functionalized graphene on the mechanical properties and thermal conductivity of LLDPE composites

Abstract Due to its high thermal conductivity, graphene finds extensive application in thermal composite materials. However, akin to polymer composites containing other fillers, the thermal resistance at the interface between graphene and the polymer matrix substantially impedes heat conduction. Thus, functionalizing graphene becomes imperative to enhance its dispersibility in polymers. In this study, we synthesized the imidazolyl ionic liquid 1‐methyl‐3‐triethoxysilpropyl imidazole chloride ([MTESiPIM]Cl). Ionic liquid complexes supported by graphene (G) were synthesized via a simple ultrasonic stripping method by combining electrochemical graphene (G) with [MTESiPIM]Cl (Si‐IL@G). The Si‐IL@G/LLDPE composite was formed by blending Si‐IL@G into the linear low‐density polyethylene (LLDPE) matrix using a melt blending technique. Upon adding 5% Si‐IL@G, the tensile strength and bending modulus of Si‐IL@G/LLDPE composite reached 13.5 MPa and 348.2 MPa, respectively, marking an increase of 20.67% and 57.79% over pure LLDPE. The Si‐IL@G/LLDPE composite exhibited a thermal conductivity of 0.49 W·m⁻¹·K⁻¹, 96.0% higher than that of pure LLDPE. Given its outstanding thermal conductivity and mechanical properties, Si‐IL@G holds great potential in producing composites with high thermal conductivity. Highlights An ionic liquid with siloxanyl groups was synthesized using microwave assistance. The ionic liquid was modified onto graphene sheets using ultrasonic techniques. The study examined how ionic liquid‐modified graphene affects LLDPE structure. The thermal conductivity and mechanical properties of LLDPE were enhanced.