Vijayamohanan Harikrishnan, Bhide Parth, Boyd Dante, Zhou Zhe, Palermo Edmund F, Ullal Chaitanya K
Department of Materials Science and Engineering , Rensselaer Polytechnic Institute , 110 8th Street , Troy , New York 12180 , United States.
Langmuir. 2019 Mar 19;35(11):3871-3879. doi: 10.1021/acs.langmuir.8b03304. Epub 2019 Mar 11.
We study the effect of the microenvironment on writing chemical patterns into spirothiopyran monolayers over large areas in a single step with light. Surfaces functionalized with photoresponsive spirothiopyran are fabricated by chemically modifying amine-terminated monolayers. The merocyanine isomer selectively participates in a thiol-Michael addition reaction with maleimide-functionalized molecules, rendering these surfaces ideal for fast, mask-less direct writing. The local microenvironment of spirothiopyran is found to strongly influence the kinetics of photoswitching. The quantum yield of ring opening is found to be 17 times faster for spirothiopyran surrounded by a locally charged environment rich in guanidinium diluent molecules as compared to a closed-packed monolayer without diluents. Hydrophilic environments are also found to improve the kinetics of ring closing. Optimization of the diluent concentration leads to dramatic improvements in both contrast and yield of direct writing. This enables the monolayer to be used for maskless two-color photopatterning in which spatial control over patterning is obtained by varying the relative intensity of incident UV and green light. These experiments demonstrate the capacity of spirothiopyran monolayers to serve as a versatile toolbox for rapid, large-area surface functionalization.
我们研究了微环境对通过光在一步中在大面积上向螺硫代吡喃单分子层写入化学图案的影响。通过化学修饰胺端基单分子层制备了用光响应性螺硫代吡喃功能化的表面。部花青异构体选择性地与马来酰亚胺功能化分子参与硫醇-迈克尔加成反应，使这些表面成为快速、无掩膜直接写入的理想选择。发现螺硫代吡喃的局部微环境强烈影响光开关动力学。与没有稀释剂的紧密堆积单分子层相比，被富含胍稀释剂分子的局部带电环境包围的螺硫代吡喃的开环量子产率快17倍。还发现亲水环境可改善闭环动力学。稀释剂浓度的优化导致直接写入的对比度和产率都有显著提高。这使得单分子层可用于无掩膜双色光图案化，其中通过改变入射紫外光和绿光的相对强度来实现图案化的空间控制。这些实验证明了螺硫代吡喃单分子层作为快速、大面积表面功能化通用工具箱的能力。
