This thesis develops metallization methods on thin ultra-high molecular weight polyethylene (UHMWPE) membrane. By controlling the coating condition and the thickness of PE, various metal-PE composites are prepared for different applications. The relationships of morphology with performances, such as resistance, mechanical and optical properties, are discussed comprehensively.

In chapter 1, the background and metallization strategies are summarized and categorized by energy of metal atoms. We claimed the necessity of metal-UHMWPE system for the limitations of pure metal foils and weakness of other polymer substrates. Then the metallization methods are briefly introduced to analyze the potential utilization on ultrathin membranes. Subsequently, several objectives that are set, including...[ Read more ]

This thesis develops metallization methods on thin ultra-high molecular weight polyethylene (UHMWPE) membrane. By controlling the coating condition and the thickness of PE, various metal-PE composites are prepared for different applications. The relationships of morphology with performances, such as resistance, mechanical and optical properties, are discussed comprehensively.

In chapter 1, the background and metallization strategies are summarized and categorized by energy of metal atoms. We claimed the necessity of metal-UHMWPE system for the limitations of pure metal foils and weakness of other polymer substrates. Then the metallization methods are briefly introduced to analyze the potential utilization on ultrathin membranes. Subsequently, several objectives that are set, including properties and applications of metal-PE by electroless deposition (ELD), along with low power and critical power magnetron sputtering.

A comprehensive literature review is introduced in chapter 2. Firstly, massive polymer substrates are listed and commented, including soft elastomers and traditional hard membranes. Then, UHMWPE is chosen as the best material for its high flexibility, breaking strength and high adhesion. Next, the metallization method, including ELD, vacuum evaporation and magnetron sputtering are carefully discussed from the theory and applications on polymers. Especially, based on the extremely thin PE substrate and different energy change during metallization, 5 key problems are raised to deep theoretical discussion. They are breaking of ultrathin metal foil, energy distribution of metal atoms, heat limitation, adhesion of metal on PE and crystallization mode.

In chapter 3, ELD method is used to copper plating on various PE membrane. We found outstanding conformal copper layer on PE fibers in nanoscale. This ultrathin and ultralight CuPE passed massive flexibility test along with resistance test, so it is considered as current collector of anode in lithium-ion batteries. After graphite painting, these anode sheets not only increase the energy density, but also show great adhesion and robustness under severe distortion. Then, in rate test, half-cell long cycling, and full-cell long cycling, CuPE act well with negligible extra energy decay and side reaction. Apart from the direct current working conditions above, we also confirm the good electromagnetic shielding ability of CuPE.

Chapter 4 is an extension of ELD for nickel. Though the mechanical properties of NiPE is similar to CuPE, the impurities of reducer, such as phosphorus and boron, increase resistance dramatically, limiting their further application.

In chapter 5, magnetron sputtering is utilized with safe low powers. The crystallization of metal depositions on porous PE is carefully compared to those on other hard and flat substrates. A classic Volmer-Weber mode of metal crystallization is observed on PE, which has similar tendencies with other substrates during thickening. The only difference is delayed resistivity decline for the high porosity of PE.

In chapter 6, a 5-period change during power increasing is found by change of resistance and roughness. Especially at critical power ranges, a unique partial melted PE fibers on surface combine with isolated metal nanoparticles. The porosity of our PE can contain about equivalent 40 nm silver at isolated state by chain explosion during melting. We found that surface melting is an immediate and localized process during deposition. This AgPE has astonishing optical properties for the isolation of silver nanoparticles (AgNPs), such as mirror reflection at front side, purple or magenta transmission, and golden reflection at back side. It is driven by the close distance of AgNPs, which influences the distribution of localized surface plasmonic resonance. At other frequencies, this AgPE act as a transparent membrane, so it is used as a smart window to reflect sunlight but pass communication signal. Finally, we found that cooling substrate can eliminate surface melting, which allows conductive and insulative part on a same membrane with single deposition.

Finally, we can conclude that ultrathin UHMWPE membrane can be metalized by various methods, even under high energy. Metal-PE composite has great performances of flexibility, area density, and resistance. It is suitable for next generation current collector, electromagnetic wave filter and heating membranes.