Development of responsive polymer-based nanocomposites for sensing applications

Abstract

The objectives of this thesis are two-fold. First, we develop a platform of responsive polymer grafted two-dimensional (2D) materials for various applications including smart nanosensors. We systematically investigated the unique properties of responsive polymer-grafted 2D materials to understand their mechanisms and to control the optical behavior and responsivity. The second objective is “development of a noninvasive treatment with low side effects for critical health issues such as cancer and tuberculosis” to solve the problems in the real world. The responsive polymer-based nanocomposites and other various sensitive nanocomposites are investigated as an efficient platform for promising biological and environmental applications. In Chapter 2, we address the first point by designing a thermally responsive polymer- grafted molybdenum disulfide ($MoS_2$), which is a photothermal agent with self-temperature feedback by introducing the mechanism of Förster Resonance Energy Transfer (FRET). Chapter 3 is associated with the systematical study of the optical properties of the polymer integrated MoS2 according to the polymer length and areal density to understand and optimize this system for further applications. In Chapter 4, we focus on a control of the selectivity of responsive polymers using random copolymerization to sense the neutral pH. We suggest the designed pH-responsive polymer-grafted $MoS_2$ nanocomposites show dual functions: in situ pH-monitoring and photothermal heating. After encapsulating the pH detectable $MoS_2$ in uniform microcapsules, they are utilized in a real-time detection of cancer cells and photothermal therapy by exposing the light source, resulted in cell death. In Chapter 5, we extend the sensing range of the $MoS_2$ system and improve the visual recognition of detecting stimuli through the colorimetric responses by attaching the three different multicolor block copolymers on the 2D $MoS_2$ nanosheets. In Chapter 6, to detect the multi-components or stimuli at once, we develop the sensor array platform using the series of composites of ionic liquid and carbon nanotube. Due to the different absorption selectivity of the nanocomposites, the sensor arrays recognize the mixture of organic compounds in real-time as monitoring the change of the electrical resistance.