title: In situ photopolymerization approach to polymer composite materials
Creators: name: Peng, Xiaotong
Publisher: name: The Australian National University
Year: 2025

description: This thesis explores the development of high-performance polymer nanocomposites through photopolymerization, a technique that has gained significant attention due to its rapid, energy-efficient, and environmentally friendly nature. Photopolymerization offers unique advantages over conventional methods by enabling solvent-free, spatially controlled polymerization at ambient temperatures using light. This precision and adaptability are particularly valuable for fabricating nanocomposite materials, where achieving uniform dispersion of nanofillers is crucial to optimizing properties. By incorporating functionalized nanomaterials, photopolymerization facilitates the formation of polymer networks with enhanced mechanical, optical, and functional attributes, making it a preferred approach for creating materials tailored to specific industrial, biomedical, and environmental applications. Each chapter in this thesis presents a distinct photopolymerization strategy to integrate dual-role nanomaterials that function as both photoinitiators and reinforcing agents, yielding composites with enhanced stability, functionality, and potential for scalable production. Chapter 1 provides a comprehensive review of the latest advances in photopolymerization techniques for fabricating polymer composites with functionalized nanofillers. It emphasizes the significance of selecting suitable monomers and nanofillers, modifying filler surfaces, and optimizing interfacial interactions to improve material properties. This chapter highlights key applications in sensors, gas separation, and biomedical fields, establishing a foundation for subsequent experimental work. Chapter 2 details the synthesis of triazine-coated silica nanoparticles (Si-triazine NPs), which act as both photoinitiators and reinforcing agents under LED (410 nm) irradiation. These nanoparticles effectively initiate free radical polymerization of trimethylolpropane triacrylate (TMPTA) while enhancing mechanical strength and reducing shrinkage in the polymer matrix. The study further evaluates the impact of different Si-triazine NP concentrations on photopolymerization kinetics, highlighting optimal formulations for improved migration stability and mechanical integrity. Chapter 3 investigates the dual-role potential of CsPbBr3 quantum dots (QDs) as photoinitiators and emitters within polymer composites for optoelectronic applications. By combining the QDs with diphenyliodonium hexafluorophosphate (Iod) or ethyl 4-(dimethylamino) benzoate (EDB), the study enhances photoinitiation efficiency, achieving composites with superior photoluminescence and long-term stability. The research demonstrates that Iod as an additive significantly improves photoinitiation, enhancing the composite's performance in luminescent displays and lighting. Chapter 4 introduces a novel approach to create polymer/MOF (metal-organic framework) composites by functionalizing UiO-66 MOFs with visible-light-sensitive photoinitiators, N-(1-pyrenyl)glycine (NPYG) and triazine. These modified MOFs enable rapid, thick curing under LED light, improving structural stability. UiO-66-NPYG composites demonstrate potential for high-resolution 3D printing, while UiO-66-Tz composites exhibit selective cationic dye absorption, showing promise for water purification applications. Chapter 5 explores a hybrid system of TiO2 and carboxylated nanodiamonds (NDs) in zwitterionic hydrogels derived from 2-(N-3-Sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate (SBMA). This system enhances both the mechanical strength and anti-fouling properties of SBMA hydrogels, with TiO2-ND acting as a photoinitiator and reinforcing agent. The hydrogels demonstrate increased electron-hole separation efficiency, enabling enhanced photopolymerization and potential moisture-sensing applications.