Solvatochromic Sensor Systems Based on Supramolecular Polydiacetylenes

Abstract

Polydiacetylenes (PDAs) have been extensively investigated as sensor materials due to the unique optical properties. PDAs undergo distinct color change, typically blue to red, when their π-conjugated backbones are distorted under influence of various environmental perturbations. The stimuli-responsive colorimetric responses facilitate simple detection of target with naked eye. In this dissertation, various solvent sensor systems were developed based on the solvatochromic property of PDAs. Firstly, we demonstrate a new colorimetric hydrocarbon sensor system. Rational design of colorimetric sensors for saturated aliphatic hydrocarbons (SAHCs) is difficult owing to the nonpolar nature and lack of functional groups that can interact with probe molecules. By taking advantage of a PDA and the hydrocarbon-induced swelling property of polydimethylsiloxane (PDMS), a sensor film is fabricated that enables simple, colorimetric differentiation depending on the chain length of the hydrocarbon. Secondly, a novel type of hydrochromic PDA-based system that is compatible with inkjet-printing on conventional paper was developed. We synthesized an amphiphilic diacetylene (DA) monomer that contains a hydrophilic imidazolium head-group, PDA derived from this monomer displays the water-induced colorimetric response. Furthermore, the immobilization of hydrochromic PDA on paper was demonstrated using inkjet-printing method and hydrochromic PDA-coated paper was applied to human sweat pore mapping. Thirdly, a tetrahydrofuran (THF)-selective optical sensor was investigated. Most of the PDAs show non-specific solvatochromisms in response to various organic solvents. The solvatochromic response of PDAs is intimately related with the solubility of its DA monomer. The key for controlling the solvent-induced colorimetric responses of PDAs is to manipulate the structure of diacetylene monomer. Headgroup of a DA monomer was modified with introducing amide group and aromatic ring to make the monomer soluble in only THF among the 11 organic solvents. As a result, the PDA derived from this monomer exhibits the THF-specific solvatochromism. Fourthly, a smart VOCs (volatile organic compounds) sensor system was developed with PDAs array and mobile phone application. The PDAs array was fabricated with 4 different solvatochromic PDA derivatives on paper substrate using inkjet-printing method. It displayed the particular color patterns upon exposure to 11 organic solvents. The solvent-induced color transition of PDAs array was quantified with red values and hue values and a database of 11 organic solvents was constructed with these values. The mobile application was developed which is consisted of taking a photos and evaluating the solvatochromic response of PDAs array. It allowed an immediate distinction of 11 common organic solvents without expensive, complicated analytical equipment.|폴리다이아세틸렌은 고유의 광학적 특성을 가지고 있어 센서소재로써 광범위하게 연구되고 있다. 폴리다이아세틸렌은 다양한 외부환경 변화에 의해 π-전자들이 비편재화되어있는 주쇄가 뒤틀리면서 청색에서 적색으로의 뚜렷한 색 변화를 나타낸다. 이러한 자극감응에 의한 색 변화현상은 감지 대상을 육안으로 쉽게 탐지할 수 있게 해준다. 본 연구에서는 폴리다이아세틸렌의 용매 변색 특성을 이용한 다양한 유기용매 센서 시스템을 개발하였다. 첫째로, 색 변화를 이용한 새로운 탄화수소 센서 시스템을 개발하였다. 지방족 탄화수소는 무극성의 고유 성질과 센서물질과 반응할 수 있는 작용기가 없어, 색을 이용한 탄화수소 센서를 만드는 것은 매우 어렵다. 그러나, 자극에 의해 색이 변하는 폴리다이아세틸렌과 탄화수소에 의해 팽윤현상을 보이는 폴리디메틸실록산의 특성을 융합함으로써 탄화수소의 사슬길이에 따라 색변화의 차이를 나타내는 센서 필름을 개발하였다. 두번째로, 잉크젯 프린팅을 이용한 종이 기판의 수변색 폴리다이아세틸렌 시스템을 개발하였다. 말단에 친수성의 이미다졸륨기가 도입된 양친성의 다이아세틸렌 단량체를 합성하고, 이 단량체로부터 형성된 폴리다이아세틸렌이 물에 의한 변색특성을 보이는 것을 확인하였다. 뿐만 아니라, 잉크젯 프린팅 방법을 통해 수변색 폴리다이아세틸렌을 종이 기판 위에 고정화 시키는데 성공하였고, 수변색 폴리다이아세틸렌이코팅된 종이는 사람의 땀샘을 맵핑하는데 적용할 수 있었다. 세번째로, 여러 유기용매 중 테트라히드로퓨란 (THF)에 의해서만 선택적으로 색 변화를 보이는 센서를 개발하였다. 대부분의 폴리다이아세틸렌은 여러 유기용매에 대해 비선택적인 용매 변색 특성을 나타낸다. 폴리다이아세틸렌의 용매 변색 특성은 그 단량체의 용해도와 아주 밀접한 관계가 있어, 다이아세틸렌 단량체의 구조 변경을 통해 유기용매에 대한 용해도를 조절함으로써 폴리다이아세틸렌의 용매 변색 특성을 제어할 수 있다. 본 연구에서는 단량체 말단에 π- π 적층 결합을 할 수 있는 방향족 그룹과 수소결합을 할 수 있는 아마이드 그룹을 도입함으로써, 11종의 유기용매 중 테트라히드로퓨란에 의해서만 용해되는 다이아세틸렌 단량체를 합성하였다. 그 결과, 이 단량체로부터 형성된 폴리다이아세틸렌은 테트라히드로퓨란에 선택적으로 용매 변색 특성을 나타내게 된다. 네번째로, 폴리다이아세틸렌 어레이와 스마트폰 어플리케이션을 이용한 스마트 VOC 센서 시스템을 개발하였다. 서로 다른 용매 변색 특성을 보이는 4 종류의 폴리다이아세틸렌 유도체들을 종이 위에 잉크젯 프린팅하여 폴리다이아세틸렌 어레이를 제작하였고, 제작한 폴리다이아세틸렌 어레이는 11 종의 유기용매에 의해 각각 특징적인 색 패턴을 나타낸다. 각각의 용매 노출에 의해 나타난 폴리다이아세틸렌 어레이의 색 변화를 적색(R) 값과 색상(H) 값으로 수치화하고, 이 값들을 통해 11종의 유기용매에 대한 데이터베이스를 구축하였다. 이러한 폴리다이아세틸렌 어레이의 용매변색현상을 촬영하여 색 변화 수치를 계산할 수 있는 모바일 어플리케이션을 제작하여, 고가의 복잡한 분석장비가 없이도 11 종의 유기용매를 쉽게 구별할 수 있는 센서시스템을 개발하였다.; Polydiacetylenes (PDAs) have been extensively investigated as sensor materials due to the unique optical properties. PDAs undergo distinct color change, typically blue to red, when their π-conjugated backbones are distorted under influence of various environmental perturbations. The stimuli-responsive colorimetric responses facilitate simple detection of target with naked eye. In this dissertation, various solvent sensor systems were developed based on the solvatochromic property of PDAs. Firstly, we demonstrate a new colorimetric hydrocarbon sensor system. Rational design of colorimetric sensors for saturated aliphatic hydrocarbons (SAHCs) is difficult owing to the nonpolar nature and lack of functional groups that can interact with probe molecules. By taking advantage of a PDA and the hydrocarbon-induced swelling property of polydimethylsiloxane (PDMS), a sensor film is fabricated that enables simple, colorimetric differentiation depending on the chain length of the hydrocarbon. Secondly, a novel type of hydrochromic PDA-based system that is compatible with inkjet-printing on conventional paper was developed. We synthesized an amphiphilic diacetylene (DA) monomer that contains a hydrophilic imidazolium head-group, PDA derived from this monomer displays the water-induced colorimetric response. Furthermore, the immobilization of hydrochromic PDA on paper was demonstrated using inkjet-printing method and hydrochromic PDA-coated paper was applied to human sweat pore mapping. Thirdly, a tetrahydrofuran (THF)-selective optical sensor was investigated. Most of the PDAs show non-specific solvatochromisms in response to various organic solvents. The solvatochromic response of PDAs is intimately related with the solubility of its DA monomer. The key for controlling the solvent-induced colorimetric responses of PDAs is to manipulate the structure of diacetylene monomer. Headgroup of a DA monomer was modified with introducing amide group and aromatic ring to make the monomer soluble in only THF among the 11 organic solvents. As a result, the PDA derived from this monomer exhibits the THF-specific solvatochromism. Fourthly, a smart VOCs (volatile organic compounds) sensor system was developed with PDAs array and mobile phone application. The PDAs array was fabricated with 4 different solvatochromic PDA derivatives on paper substrate using inkjet-printing method. It displayed the particular color patterns upon exposure to 11 organic solvents. The solvent-induced color transition of PDAs array was quantified with red values and hue values and a database of 11 organic solvents was constructed with these values. The mobile application was developed which is consisted of taking a photos and evaluating the solvatochromic response of PDAs array. It allowed an immediate distinction of 11 common organic solvents without expensive, complicated analytical equipment.