光引发聚合法制备光致失黏胶

Preparation of ultra violet dismantlble adhesion by photoinitiation

利用光引发聚合法取代传统热聚合合成一种能够制备光致失黏胶的聚丙烯酸酯类共聚物,称为基胶。将基胶与适量的光引发剂及多光敏官能团低聚物复配,得到目标产物。在UV光照前,展现了很好的粘接性能,180°剥离强度可以达到24N/25mm;在20m W/cm^2的365nm波长UV光照下照射20s后,光敏树脂反应产生交联,与直链分子形成互穿网络结构,导致180°剥离强度降至几乎为零,从而展示了很好的失黏性能,便于拆离,而不损坏元器件。进一步探究了基胶成分、多光敏官能团低聚物的种类、用量等多个参数对光致失黏胶综合性能的影响。最后通过扫描电镜,对其失黏机理进行讨论,有两个关键因素导致光照后胶黏剂失黏:低聚物交联过程,引起体积的收缩,与基材粘接面积减小;互穿网络结构造成基胶失去橡胶弹性,表现塑料特性。

A kind of acrylate copolymer called matrical cohesive is synthesized by photopolymerization method to replace the traditional thermal polymerization method. The target-product prepared by the matrical cohesive is compounded with certain amount of initiator and multi-photosentitive-functional groups oligomer or monomer, which exhibits excellent adhesion property under UV irradiation. The 180° peel strength can reach 24N/25mm. However, when exposed to UV light of 20mW/cm^2 and 365nm for 20s, the multi-photosensitive oligomer can react with each other and form cross-linked structure. Linear polymer penetrates into the cross-linked structure and forms interpenetrating network structure, which decreases the 180° peel strength down to zero. So it is very convenient to detach and have no harm to the jointed objects. Furthermore, the effects of copolymer composition, type of photosensitive oligomer or monomer, and the number of functional groups on the dismantlble property have been investigated. The mechanism is discussed through SEM. The cross-linked structure leads to the volume contraction and reduces the effective bonding area, while the interpenetrating network makes it lose rubber elasticity and exhibit plastic properties.