Functionalized nanoporous materials with high porosity and high specific surface area have become promising materials for appealing applications. Gyroid phase with ordered, bi-continuous networks in 3D space is one of the most appealing morphologies for practical applications due to its high specific interfacial surface area. In this study, we aim to fabricate nanoporous gyroid SiO2 materials from templated sol-gel reaction using degradable block copolymer with gyroid-forming nanostructure as a template, and then to functionalize the nanoporous materials using “smart” polymer, poly(2-dimethylaminoethyl methacrylate) (PDMAEMA), brushes via “grafting from” method to give double stimuli-responsive properties. By taking advantage of the environmental stimuli, both thermal and pH, the pore features can be well defined by stretching and re-coiling of the grafted PDMAEMA brushes because of their adjustable chain conformation with reversible character. The grafting PDMAEMA on the inner wall of the nanoporous materials is evidenced by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The responsive properties with respect to environmental stimuli can be successfully traced by temperature-resolved small angle X-ray scattering (SAXS) in aqueous environment. Owing to the high specific surface area, 3D pore network, biocompatibility and environmental response, the functionalized nanoporous gyroid SiO2 are further demonstrated as stimuli-responsive controlled release system. As a result, the nanoporous SiO2 with tunable pore size can be fabricated to give promising properties for various applications, such as environment-selective delivery systems, bio-mimetic on/off gates, and specific environmental detectors.

Functionalized nanoporous materials with high porosity and high specific surface area have become promising materials for appealing applications. Gyroid phase with ordered, bi-continuous networks in 3D space is one of the most appealing morphologies for practical applications due to its high specific interfacial surface area. In this study, we aim to fabricate nanoporous gyroid SiO2 materials from templated sol-gel reaction using degradable block copolymer with gyroid-forming nanostructure as a template, and then to functionalize the nanoporous materials using “smart” polymer, poly(2-dimethylaminoethyl methacrylate) (PDMAEMA), brushes via “grafting from” method to give double stimuli-responsive properties. By taking advantage of the environmental stimuli, both thermal and pH, the pore features can be well defined by stretching and re-coiling of the grafted PDMAEMA brushes because of their adjustable chain conformation with reversible character. The grafting PDMAEMA on the inner wall of the nanoporous materials is evidenced by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The responsive properties with respect to environmental stimuli can be successfully traced by temperature-resolved small angle X-ray scattering (SAXS) in aqueous environment. Owing to the high specific surface area, 3D pore network, biocompatibility and environmental response, the functionalized nanoporous gyroid SiO2 are further demonstrated as stimuli-responsive controlled release system. As a result, the nanoporous SiO2 with tunable pore size can be fabricated to give promising properties for various applications, such as environment-selective delivery systems, bio-mimetic on/off gates, and specific environmental detectors.

Contents
Abstract I
Contents III
List of Figures VI
List of Tables and Schemes VII
Chapter 1 Introduction 1
1.1 Self Assembly of Block Copolymers 1
1.2 Gyroid Phase from BCP Self-Assembly 2
1.3 Nanoporous Materials 7
1.3.1 Nanoporous polymers 8
1.3.2 Nanoporous ceramics 16
1.3.3 Templated sol-gel reaction 21
1.4 Surface Functionalization 27
1.4.1 Organically functionalized nanoporous SiO2 28
1.4.2 Surface-initiated atom transfer radical polymerization
(SI-ATRP) 32
1.4.3 Poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) with double stimuli-responsive properties 34
1.5 Applications 37
Chapter 2 Objectives 41
Chapter 3 Materials and Experimental Methods 44
3.1 Materials 44
3.2 Synthesis of PS-PLLA BCP 46
3.3 Synthesis of halogen-functionalized initiator (2-bromo
thioisobutyrate, MPTS-Br) 51
3.4 ATRP of PDMAEMA 51
3.5 Sample Preparation 51
3.5.1 Sample preparation for nanoporous PS template 52
3.5.2 Sample preparation for templated sol-gel reaction 52
3.5.3 Sample preparation for nanoporous gyroid SiO2 54
3.5.4 Sample preparation for PDMAEMA functionalized nanoporous
gyroid SiO2 54
3.5.5 Sample preparation for riboflavin-loaded PDMAEMA
functionalized nanoporous gyroid SiO2 55
3.6 Instrumentation 55
3.6.1 Nuclear magnetic resonance spectroscopy (NMR) 55
3.6.2 Gel permeation chromatography (GPC) 56
3.6.3 Small-angle x-ray scattering (SAXS) 56
3.5.4 Fourier transform infrared spectroscopy (FTIR) 57
3.5.5 Field-emission scanning electron microscopy (FESEM) 57
3.5.6 Transmission electron microscopy (TEM) 57
3.5.7 Fluorescence spectroscopy 58
Chapter 4 Results and Discussion 59
4.1 Fabrication of Nanoporous Gyroid SiO2 59
4.1.1 Gyroid PS/SiO2 nanohybrids 59
4.1.2 Nanoporous gyroid SiO2 60
4.2 Surface Functionalization of Nanoporous Gyroid SiO2 62
4.2.1 Halogen-functionalized initiator (MPTS-Br) 63
4.2.2 Si wafers with SiO2 as a model system for SI-ATRP 65
4.2.3 Characterization of PDMAEMA functionalized nanoporous
gyroid SiO2 67
4.3 Double Stimuli-Responsive Properties of PDMAEMA Functionalized Nanoporous Gyroid SiO2 72
4.4 PDMAEMA Functionalized Nanoporous Gyroid SiO2 as
Environment-Selective Delivery Systems 76
4.4.1 Cumulative release profiles in response to environmental
changes 77
4.4.2 Kinetic modeling on cumulative release profiles 78
Chapter 5 Conclusion 80
Chapter 6 References 82

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