偶氮苯高分子光控可逆黏合剂的制备及性能

Preparation and Properties of Light-Controlled Reversible Adhesives of

通过原子转移自由基聚合(ATRP)制备了一种能在紫外光和可见光下发生固液转变的可逆黏合剂,其主链结构为甲基丙烯酸甲酯,侧链为以6个亚甲基为间隔基和短链聚乙二醇(PEG)为尾基的偶氮苯聚合物(PAzo-PEG)。偶氮苯基团在紫外光和可见光的辐照下发生可逆的顺反异构。采用紫外-可见吸收光谱研究了PAzo-PEG的可逆光致异构过程,用差示扫描量热仪(DSC)研究其固液转变。结果表明:反式异构体的Tg高于室温,顺式异构体的Tg低于室温,PAzo-PEG在光照下宏观表现出可逆固液转变的现象。固态和液态的PAzo-PEG不同的黏附能力赋予了PAzo-PEG光控可逆黏合的性能。实验测得其反式状态下最大黏附强度能达到0.97 MPa,而顺式状态下PAzo-PEG的黏附强度降低到0.03 MPa。在3个黏附循环后其黏附强度仍能保持初始黏附强度的80%。

A reversible adhesive PAzo-PEG,with a main chain structure of methyl methacrylate and a side chain of azobenzene(Azo)having six methylene spacer groups and a short polyethylene glycol(PEG)chain as a tail group,can undergo solid to liquid transformation under UV and visible light irradiation.It was prepared by atom transfer radical polymerization(ATRP).The azobenzene group undergoes reversible trans-to-cis isomerization under UV and visible light irradiation,and the process is reversible.The reversible photoisomerization process of solid materials was studied by UV-Vis absorption spectroscopy.The solid-to-liquid transition was studied by differential scanning calorimetry(DSC).Results showed that the solid-liquid transition is due to the different glass transition temperatures(Tg)of the cis and trans isomers,and Tg of trans is higher than room temperature while Tg of cis is lower than room temperature,so PAzo-PEG macroscopically exhibits reversible solid-to-liquid transition under light irradiation.The different adhesion capabilities of solid and liquid states of PAzo-PEG endow it with reversible adhesive properties.The solid state exhibits better adhesion properties,with an adhesion strength of 0.97 MPa measured experimentally,while the adhesion strength of PAzo-PEG in the cis state is reduced to 0.03 MPa.After three cycles of adhesion,the adhesive strength maintained 80%of the original strength.