Double hydrophilic Block Copolymer-Templated Nanoparticle and Energy Application

Abstract

This thesis describes a variety of utilization of double hydrophilic block copolymer (DHBC), in the synthesis of NP (NP) and its broad applications. Double hydrophilic block copolymer can be induced to form a micellar structure through electrostatic or coordinative interaction with metal precursor in aqueous solution. These interactions can then lead to the synthesis of metal or metal oxide NP with the treatment of proper reductant. Poly(ethylene oxide)-block-poly(acrylic acid) (PEO-b-PAA) copolymer used in this thesis consists of both water-soluble, and chemically distinct blocks. These different functionalities in each block are effectively utilized to synthesize NP with a controlled size and shape, further influencing the properties of resulting NP. Au NPs can be prepared by interaction between metal precursor and carboxylate groups in PAA block through coordinative bonding. It is found that the size of Au NPs is independent of the molecular weight of PAA, while the micellar structure with metal precursor is mainly induced by PAA block. This result indicates the density of DHBC in a single NP decreases when the molecular weight of PAA block increases. This polymeric density difference of each NP shows the different stability in a harsh condition. We have also demonstrated that additional Ag shell structure on Au NPs could be synthesized by utilizing the PEO block on the surface of Au NP template by DHBC, resulting in Au-Ag core-shell nanostructure. Interestingly, we found the changes in configuration of core-shell NP as well as the tunable thickness of Ag shell could be attributed to PEO chains, leading to the transition of intrinsic plasmonic absorption band in a wide spectrum. This phenomenon allows the integration of NPs into optoelectronic devices with enhanced properties. Considering a wide range of tunability and functionalities of DHBCs, we anticipate that the DHBCs can offer a novel synthetic approaches for nanomaterials and allow the NPs to be applicable into various applications including biological and energy fields.