Wang Rongrong, Huang Xirong
Key Laboratory of Colloid and Interface Chemistry of Ministry of Education, Shandong University, Jinan 250100, China.
ACS Omega. 2021 Jul 28;6(31):20699-20709. doi: 10.1021/acsomega.1c03150. eCollection 2021 Aug 10.
The hydrophobic ionic liquid [Cmim][PF] (1-octyl-3-methylimidazolium hexafluorophosphate)-based bicontinuous microemulsion stabilized by the anionic surfactant [Cmim][AOT] (1-butyl-3-methylimidazolium bis(2-ethylhexyl) sulfosuccinate) was first tried as a medium for horseradish peroxidase (HRP)-triggered oxidative polymerization of aniline. The effects of the mass ratio of [Cmim][PF]-to-water (α), the mass fraction of [Cmim][AOT] in the total mixture (γ), and temperature () on the enzymatic polymerization were investigated using UV-vis-NIR absorption, electron spin resonance, and small-angle X-ray scattering spectroscopy techniques. The bicontinuous microemulsion is demonstrated to play a template role in the biosynthesis of polyaniline (PANI). The conductivity of the resulting PANI depends on the microemulsion microstructure and the microstructure- and -dependent catalytic properties of the solubilized HRP. With the increase in α, the conductivity of the synthesized PANI decreases due to the increase in the template curvature (decrease of the microdomain size) and the decrease in the activity and stability of HRP. Compared with α, γ has little effect on the microdomain size of the template; so, the γ-dependent change in the conductivity of PANI is mainly caused by the changes of the microstructure-dependent activity and stability of HRP. Over the range of 20-35 °C, has little effect on the microdomain size, but it greatly changes the activity and stability of HRP. With the increase in , the activity of HRP increases steadily, but its stability decreases significantly, which should be one of the reasons why the conductivity of PANI decreases with increasing . In conclusion, lower values of α, γ, and are favorable for the biosynthesis of conductive PANI. The present study not only deepens the insight into the role of the template in the process of PANI synthesis, but also opens up a green new way for the biosynthesis of the conducting polymer.
首次尝试将由阴离子表面活性剂[Cmim][AOT]（1-丁基-3-甲基咪唑双（2-乙基己基）磺基琥珀酸盐）稳定的基于疏水性离子液体[Cmim][PF]（1-辛基-3-甲基咪唑六氟磷酸盐）的双连续微乳液用作辣根过氧化物酶（HRP）引发的苯胺氧化聚合反应的介质。使用紫外-可见-近红外吸收光谱、电子自旋共振和小角X射线散射光谱技术研究了[Cmim][PF]与水的质量比（α）、[Cmim][AOT]在总混合物中的质量分数（γ）以及温度（）对酶促聚合反应的影响。结果表明，双连续微乳液在聚苯胺（PANI）的生物合成中起模板作用。所得PANI的电导率取决于微乳液的微观结构以及溶解的HRP的微观结构依赖性和温度依赖性催化性能。随着α的增加，合成的PANI的电导率降低，这是由于模板曲率增加（微区尺寸减小）以及HRP的活性和稳定性降低所致。与α相比，γ对模板的微区尺寸影响较小；因此，PANI电导率随γ的变化主要是由HRP的微观结构依赖性活性和稳定性的变化引起的。在20-35°C范围内，对微区尺寸影响较小，但它极大地改变了HRP的活性和稳定性。随着的增加，HRP的活性稳步增加，但其稳定性显著降低，这应该是PANI电导率随升高而降低的原因之一。总之，较低的α、γ和值有利于导电PANI的生物合成。本研究不仅加深了对模板在PANI合成过程中作用的理解，还为导电聚合物的生物合成开辟了一条绿色新途径。
