Styrenic Block Copolymer-Based Pressure Sensitive Adhesives without Volatile Compounds Using Organic Eutectic Liquid

Pressure sensitive adhesives (PSAs) based on styrenic block copolymers are commonly used in daily life and industry applications owing to their ability to rapidly adhere to surfaces with the application of low pressure at room temperature. Because of rising environmental issues, the demand for eco-friendly PSAs has considerably increased. In this regard, a nonvolatile organic eutectic liquid (EL) was developed as a substitute for the volatile organic diluent and tackifier, which are conventional components of PSAs. The poly(styrene- b -butadiene- b -styrene) (SBS) block copolymer was used as a model base polymer. The substitution of the diluent and tackifier by the EL considerably simplifies the PSA preparation process by eliminating the need for solution casting and solvent recovery steps. Additionally, it ensures the safety of manufacturers and users as the use of volatile and toxic components is avoided. Owing to the chemical structure similarity, the EL preferentially plasticized the polystyrene block, effectively increasing tackiness and enhancing damping properties at room temperature even at relatively low EL loadings (≤30 wt %). By simply incorporating EL into the SBS matrix, lap shear strength could be enhanced by 524% at most. Moreover, the use of the EL renders the SBS-based PSA particularly suitable for applications under rapid-shear conditions.