Block copolymer self-assembly: from thin film formation to inorganic nanostructures

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Giraud, Elsa Coline
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University College Cork
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Upon self-assembly, block copolymers (BCP) can form a variety of well-ordered nanofeatures, that makes them prime candidates for use in a wide range of applications, and for alternative approaches to traditional “top-down” processes in the microelectronic industry. Self-Assembly of block copolymer thin films is widely documented, notably thermal and vapour solvent annealing. Chapter 1 introduces the main reasons and motivations for the research carried out during this PhD. It provides a brief overview of the state of the semiconductor industry, the principle of self-assembly in block copolymer thin films and different means of selective inorganic infiltration from vapour- and liquid- phase techniques to yield nanostructures with a one-to-one registration to the block copolymer scaffold. Chapter 2 focuses on the structural rearrangement of PS-b-PEO micellar thin film using an argon plasma treatment, an interesting alternative to conventional thermal and solvent vapour annealing. This process is believed to be a balance between reorganisation and possible damage on the surface due to cross-linking and etching induced. With the right conditions, perpendicular and parallel arrangement of PEO blocks are obtained within the PS matrix, proving that plasma treatment could be a suitable technique to improve the order of self-assembled thin films. Chapter 3 details the formation of titanium dioxide nanostructures using a vapour approach for the selective infiltration of the hydrophilic PEO block. This simple, yet effective approach, relies on the volatility of the precursor, the amphiphilic properties of the block copolymer and the relative humidity to form nanodots and nanowires. Grazing incidence small angle x-ray scattering was employed to analyse the ordering of the nanowires at different stages during exposure to the titanium precursor. In Chapter 4, a liquid-phase approach was used to produce europium-doped gadolinium oxide exhibiting characteristic photoluminescence peak that could find application in biosensing due to the small size of nanodots and nanowires. Chapter 5 summarizes the key achievement of each chapter and examines potential future directions related to the results discussed in Chapter 2 – 4.
Block copolymer , Nanopattern , Phase separation
Giraud, E. C. 2019. Block copolymer self-assembly: from thin film formation to inorganic nanostructures. PhD Thesis, University College Cork.