Department of Chemistry, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, China.
ACS Appl Mater Interfaces. 2010 Feb;2(2):566-74. doi: 10.1021/am9008727.
We successfully synthesized hyperbranched poly(triazole)s by in situ click polymerization of diazides 1 and triyne 2 monomers on different metal surfaces (copper, iron, and aluminum) and characterized their adhesive properties. Optimizations were performed to obtain high adhesive strength at different temperatures by analyzing the effects of curing kinetics, annealing temperature and time, catalyst, monomer ratio, surface conditions, alkyl chain length of diazides 1, etc. The adhesive bonding strength with metal substrate is 2 orders of magnitude higher than similar hyperbranched poly(triazole)s made by click polymerization and clearly higher than some commercial adhesives at elevated temperatures. With the same conditions, adhesives prepared on aluminum and iron substrates have higher adhesive strength than those prepared on copper substrate, and an excess of triyne 2 monomer in synthesis has greater adhesive strength than an excess of diazide 1 monomer. Tof-SIMS experiment was employed to understand these phenomena, and the existence of an interphase between the polymer and metal surface was found to be critical for adhesive bonding with thicker interphase (excess of triyne 2 monomer) and the higher binding energy between polymer atoms and substrate atoms (e.g., aluminum substrate) generating the higher bonding strength. In addition, the light-emitting property of synthesized polymers under UV irradiation can be used to check the failure mode of adhesive bonding.
我们成功地在不同金属表面（铜、铁和铝）上将叠氮化物 1 和三炔 2 单体进行原位点击聚合，合成了超支化聚（三唑），并对其粘结性能进行了表征。通过分析固化动力学、退火温度和时间、催化剂、单体比例、表面条件、叠氮化物 1 的烷基链长度等因素对不同温度下获得高粘结强度的影响，进行了优化。与通过点击聚合得到的类似超支化聚（三唑）相比，该粘结剂与金属基底的粘结强度高 2 个数量级，在高温下明显高于一些商业粘结剂。在相同条件下，在铝和铁基底上制备的粘结剂的粘结强度高于在铜基底上制备的粘结剂，并且在合成中三炔 2 单体过量比叠氮化物 1 单体过量具有更大的粘结强度。采用 ToF-SIMS 实验来理解这些现象，发现聚合物和金属表面之间的界面的存在对于具有更厚界面（三炔 2 单体过量）和聚合物原子与基底原子之间更高的结合能（例如，铝基底）的粘结键合是至关重要的，这会产生更高的键合强度。此外，在紫外光照射下合成聚合物的发光性能可用于检查粘结键合的失效模式。
