低模量、高弹性、高剥离强度丙烯酸酯压敏胶

Low modulus,high elasticity and high peel adhesion acrylate pressure sensitive adhesives

丙烯酸酯压敏胶广泛应用在电子器件的装配中。随着可折叠屏手机等柔性电子器件发展,传统压敏胶因无法平衡低模量、高弹性以及高剥离强度而难以满足柔性电子器件对反复动态变形的需求。以苯乙烯、丙烯酸异辛酯为单体,采用RAFT乳液聚合设计制备了聚苯乙烯-b-聚丙烯酸异辛酯-b-聚苯乙烯(SEHAS)和聚苯乙烯-b-聚丙烯酸异辛酯(SEHA)嵌段聚合物,研究两种嵌段共聚物共混体系的力学性能、黏弹性和黏结性能。发现当共混物中SEHA的含量从0(质量)提高到75%(质量)时,玻璃化温度仍为-68℃,保持不变,剪切储能模量从27 kPa下降至15 kPa,剥离强度从8.1 N/25 mm提升到10.3 N/25 mm,应变回复率仍然保持在95%以上。研究表明SEHAS/SEHA共组装是一种简便降低模量同时维持较好的交联网络完整性并提高黏弹性的新方法,能够更好地平衡压敏胶高柔性、大变形后的回弹性和良好界面黏合性之间的关系。

Acrylate pressure sensitive adhesives are widely used in the assembly of electronic devices.With the development of flexible electronics such as foldable phone,traditional pressure sensitive adhesives fail to meet the needs of flexible electronics for repeated deformation due to the trade-off effect among low modulus,high elasticity and high peel adhesion.The poly(styrene-b-2-ethylhexyl acrylate-b-styrene)(SEHAS)and poly(styrene-b-2-ethylhexyl acrylate)(SEHA)copolymers of styrene and 2-ethylhexyl acrylate were prepared by design via RAFT emulsion polymerization.The mechanical properties,viscoelasticity and adhesion properties of SEHAS/SEHA blends were studied.By adjusting the blending ratio of SEHAS/SEHA from 100/0 to 25/75,it was found that the glass transition temperature remained unchanged at-68℃,the shear storage modulus decreased from 27 kPa to 15 kPa,the peel strength increased from 8.1 N/25 mm to 10.3 N/25 mm,and the strain recovery ratio remained above 95%.SEHAS/SEHA blending turns out to be a new and facile method to significantly reduce the modulus while maintain the integrality of a network and improve viscoelasticity.Thus,very soft pressure sensitive adhesives with good elasticity and adhesion can achieve.