Self-assembled monolayers (SAMs) are highly ordered molecular assemblies, which are formed spontaneously by chemisorption of functionalized surfactants onto various solid substrates, including metals and metal oxides, and the well-defined, highly controllable structures of SAMs provide great advantages in the precise control of surface properties. This thesis presents the use of SAMs as a tool for understanding interfacial phenomena and modulating physicochemical and biological properties of solid surfaces.
$\emph{Surface Reactions}$: Surface reactions are not only fundamentally interesting but also practically contributable to surface engineering. In the fundamental aspect, reactions that occur at interfaces often show different behaviors from their solution analogues, because several factors, including solvent effect, steric effect and electronic effect, could affect the chemical reactivity of functional groups at surfaces. Practically, surface reactions are required for various applications in surface engineering: for example, the covalent attachment of biologically-active molecules is crucial for the construction of biodevices, such as microarrays and biosensors. The work presented in this thesis addresses surface-characteristic reactions driven by proximity effect, enzymatic reaction, and micro/nanofabrication based on surface reactions.
$emph{Surface Electrochemistry}$: Electron transfer through nanometer-thick organic films is of fundamental importance to the development of nanometer-scale electronic materials. Knowledge of how chemical compositions and chemical structures affect the electron transfer between a solid substrate and a redox-active molecule is central in the study of molecular-level electron transfer. The work presented in this thesis addresses the concept of "molecular switch" and "molecular rectifier" that were operated mainly by electrostatic interactions between electroactive compounds and charged molecules on surfaces.
$emph{Bioactive Surfaces}$: The construction of solid surfaces capable of biospecific recognition/interaction of target biomolecules is one of the most critical issues to develop high-performance biological devices. Biospecific recognition on device surfaces can be achieved by the inherent strong attraction between surface-immobilized probes and target biomolecules, when nonspecific interaction between solid surfaces and biomolecules is eliminated. Therefore, it is important to develop simple, but versatile strategies for constructing biologically "inert", protein- or cell-resistant surfaces and introducing probes onto the surfaces. The work presented in this thesis addresses the construction of nonbiofouling, bioactive surfaces by the introduction of oligo or poly(ethylene glycol) compounds and the subsequent covalent functionalization.
자기조립 단분자막은 화학흡착의 과정을 통해 고체표면에 자발적으로 형성된 유기 단분자막을 말한다. 본 논문에는 고체표면에 형성된 유기물의 자기조립 단분자막을 표면에서 특징적으로 나타나는 현상을 이해하고 표면의 물리화학적 혹은 생물학적 특성을 조절하기 위한 도구로 이용한 다양한 연구내용을 기록하였다. 특히 표면 유기 반응, 전극 표면에서 전자이동의 조절, 생활성 표면의 구현이라는 세가지 주제에 연구의 초점을 맞추고 있다.
표면 유기 반응: 표면 유기 반응은 용액상에서와 다른 양상을 나타내는 경우가 많아 기초학문적인 관점에서 흥미를 유발함과 동시에 고체표면을 이용하는 다양한 영역에서 실용적으로 이용될 수 있다. 본 논문에는 인접효과에 의한 특이 표면반응, 표면 효소 반응, 그리고 표면반응을 이용한 마이크로/나노 패턴닝에 대한 연구결과를 기술하였다.
전극 표면에서 전자이동의 조절: 전극표면에서 유기 단분자막을 이용한 전자전달의 조절은 분자전자소자의 개발에 있어서 중요한 의미를 가진다. 구체적으로 금전극 표면에 형성된 이미다졸염의 단분자막과 용액중의 전기적 활성을 지닌 화합물과의 정전기적 상호작용에 의한 전자전달의 조절에 대해 연구하였다.
생활성 표면의 구현: 단백질이나 세포의 비특이적 흡착이 방지된 상태에서 생활성 탐지 물질을 표면에 도입하여 생체물질과의 선택적인 상호작용을 가능하게 하는 표면의 설계에 대해 연구하였다.
