| Author: | Gao, Ming |
| Title: | Surface-initiated atom transfer radical polymerization for polymer composites design and synthesis of specific functional properties |
| Advisors: | Cheung, C. F. Benny (ISE) Wong, Wai-yeung (ABCT) |
| Degree: | Ph.D. |
| Year: | 2024 |
| Subject: | Polymeric composites Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Industrial and Systems Engineering |
| Pages: | xvi, 179 pages : color illustrations |
| Language: | English |
| Abstract: | The most manufactured products for consumption in human daily life are polymer composites. According to various applications, these products are produced from different materials. A single material usually does not achieve all the requirements for specific functional properties. As a result, polymer composites which combines two or more materials with different properties have attracted growing attentions in recent decades. To design suitable polymer composites for specific functional applications, proper materials, and fabrication and manufacturing methods are crucial. This thesis focuses on the design and synthesis of several polymer composites with different inorganic reinforcements through surface-initiated atom transfer radical polymerization. A description of the challenges and objectives of this research project is firstly presented, followed by a literature review on the introduction of composites classification, polymer composites, different reinforcements, and synthetic methods. A photoluminescent polymer composite is fabricated through the SI-ATRP method to obtain a homogeneous polymer composite. An infrared transmissive ZnS/GO/PMMA composite is then synthesized through SI-ATRP. Hence, Co particles-located COOH-MWCNT-enhanced polymer matrix is generated through a solution blending and casting method to investigate the decorated carbon materials’ effects on the machinability of the polymer matrix. Magnetic polymer composites are fabricated through magnetic field-assisted SI-ATRP to investigate the relationship between the micro-arrangement and macro-properties of polymer composites. Firstly, a photoluminescent polymer composites was synthesized through SI-ATRP. The gained polymer composites could excite green and red two light by one light resource. The phosphors used in this chapter was synthesized through annealing in air at 1400 ℃.The existence of GO simplifies the process of SI-ATRP and works as a bridge to connect the inorganic phosphors and PMMA matrix. An infrared polymer composite was then synthesized through the same strategy. The composite shows relative high transparency of infrared light (40%) and relative low transparency of visible light (under 10%) compared with pure PMMA (50% for infrared light and 35% for visible light). These two different composites with specific optical properties were designed according to different applications, and two different additives were introduced into the polymer matrix system by the SI-ATRP technique due to the existence of GO. These two studies prove the flexibility of SI-ATRP in designing polymer composites with different purposes. The existence of GO enhances the interconnection between polymer chains and inorganic fillers and overcomes the limitations of the selection of reinforcements’ and enhances the potential application of SI-ATRP in the area of composites design and fabrication. Then, the magnetic fillers Co/COOH-MWCNTs was added into the polymer matrix by physical blending and solution casting methods to study the influence of extra magnetic field on the micro-arrangement of polymer composites. When the concentration of Co/COOH-MWCNTs was added to 0.012 wt%, the ductility of polymer composites was lightly improved compared with pure PMMA. Although the machinability was improved by the existence of carbon fibers, the dispersity of the fillers is inhomogeneous due to the gravity of fillers and the microstructure does not show significant difference compared with pure PMMA. In order to further study the influence of extra magnetic field on the micro- structure, a chemical polymerization method, SI-ATRP, was selected to fabricate homogeneous dispersed magnetic polymer composites with the assistance of a magnetic field. Polymerization was initiated by the active groups on the surface of GO-decorated magnetic nanoparticles, under the magnetic field, while the magnetic nanoparticles with polymer chains on their surface have been moved according to the direction of the magnetic field. When the concentration of magnetic additives increased to 20 wt%, a well-arranged microstructure could be observed by SEM. Under the extra magnetic field, polymer chains are drawn by the magnetic fillers and formed an arranged micro-structure which leads to enhanced thermal stability of the materials. In addition, their growing magnetic properties with the increase of magnetic particles’ concentration gives them a potential application in the magnetic responsive area. On the whole, photoluminescent polymer composites, infrared transmissive polymer composites, and magnetic polymer composites were synthesized via the SI-ATRP method with the assistance of GO. This study gives an extension of the application of SI-ATRP in the composite’s fabrication area. Furthermore, the well-arranged parts of polymer composites synthesized under a certain magnetic field provide an example to study the relationship between micro- structure and macro-properties. The work stated in this thesis is expected to have a significant and inspired impact on polymer composites design and formation mechanism of macro-properties fields. |
| Rights: | All rights reserved |
| Access: | open access |
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