Study of fabrication, characterization and application of 1-dimensional polymer nanomaterial

一維高分子納米材料的製備, 性能與應用研究

Student thesis: Doctoral Thesis

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Author(s)

  • Longbiao HUANG

Detail(s)

Awarding Institution
Supervisors/Advisors
Award date15 Jul 2014

Abstract

1-Dimensional (1D) polymer nanomaterials have been the focus of quite extensive studies due to their unique properties for various applications ranging from electronics, photonics, and energy harvest and so on. In this thesis, 1D polymer nanomaterials were fabricated following polymer melt wetting techniques which have been pioneered by Prof Martin Steinhart. The wetting kinetics of polymer melts in nanochannels for preparation of 1D polymer nanomaterials was systematically investigated under different condition. Different applications such as Field Effect Transistor, hydrophobic surface were explored. By combination with noble metal nanoparticle, 1D polymer nanomaterials decorated with metal nanoparticle have been investigated and applied for Surface Enhanced Raman Spectra. Firstly, the wetting (flowing) behaviors of polymer melts which have great influence on the preparation of 1D polymer nanowires were presented in Chapter one. Understanding and controlling the flowing of polymer melts in nanochannel is of great relevance to fundamental research and various applications. Experimental results for flowing of polymer melts through nanochannel with different roughness were presented. The roughness was tunable by noble metal nanoparticle absorption. The experimental results confirm that the increased roughness of nanochannel have significant affect to the flowing behaviors of polymer melts. At same diameter of nanochannel, higher roughness of surface significantly decrease the displacement of polymer melts in nanochannel. Secondly, Field Effect Transistor based on single polymer nanotube were presented in Chapter 2. Regioregular Poly (3-hexylthiophene) (RR-P3HT) nanotubes (200 nm in diameter) with tunable aspect-ratios from 25 to 300 were prepared through polymer melts wetting technique. The aspect-ratio tunability was achieved by controlling the wetting behavior of RR-P3HT melts in a template. The crystallinity and chain orientation of RR-P3HT were studied by GIXRD (grazing incidence x-ray diffraction), WAXD (wide-angle X-ray diffraction) and polarized photoluminescence spectroscopy and the results suggested that RR-P3HT chains in the lamellar structure prefer to be perpendicular to the axis of RR-P3HT nanotubes, forming face-on conformation in RR-P3HT nanotubes and leading to an increase in the carrier mobility of RR-P3HT. As such, the field-effect transistor based on the single RR-P3HT nanotube showed a carrier mobility of 0.14±0.02 cm2/Vs. This work reveals the advantage of aspect-ratio tunability for fabricating anisotropic semiconductor polymer nanotubes and its potential application in high performance nanodevices. Thirdly, by combination with noble metal nanoparticles, 1D polymer nanowires with homogenous noble metal monolayer were fabricated and presented in Chapter 3. A novel 3D structure of polymer nanotubes decorated with a monolayer of silver nanoparticles (AgNPs) was successfully fabricated in a low-cost and easy-fabrication way. At first, a monolayer of AgNPs was formed in the inner surface of a template with a layer-by-layer technique. Subsequently, polyethylene nanotubes were fabricated in the templates using polymer melt wetting technique. After removing the templates, the monolayer of AgNPs was successfully transferred from the template to the surface of the polyethylene nanotubes. This novel 3D structure of polymer nanotubes decorated with AgNPs possesses superhydrophobic property and shows highly sensitive detection of 4-ATP and R6G. Lastly, an novel fast universal approach to fabricate micro/nanopatterned polymer surface assembly by 1D polymer nanomaterials for hydrophobic application were presented in Chapter 4. Ultrasonic vibration-assisted anodized aluminum oxide (AAO) template wetting strategy as a fast and universal approach was utilized to fabricate micro/nanopatterns on the surfaces of diverse polymers. By using this method, various, high purity and large-area micro/nanopatterns were rapidly fabricated on the surfaces of amorphous polymers, semi-crystalline polymers, and highly crystalline polymers including conjugated polymers within tens of seconds. The micro/nanopatterned polycarbonate (PC) surfaces could be easily regulated by simply changing the welding time or the size of template. Specially, the composite micro/nanopatterns, including honeycomb-network/honeycomb-straw-like structures and arachnoid nanowires-covered nanofiber arrays, were also obtained on PC and polyethylene surfaces, respectively. The formation of these composite structures may depend on a melt drop motion mechanism. The static water contact angle measurements showed that the wettability of micro/nanopatterned PC surfaces is systematically tuned from being merely hydrophobic to being further high-hydrophobic, and to being finally super-hydrophobic by adjusting the welding time. What's more, all the fabricated micro/nanopatterned polymer surfaces display high hydrophobicity or superhydrophobicity. The results of photoluminescence spectrum, grazing incident X-ray diffraction, and high resolution transmission electron microscopy indicated that ultrasonic vibration in the process of AAO template wetting has the limited influence to the conjugated structure and high crystallinity of honeycombed poly(3-hexylthiophene) micro/nanopatterns.

    Research areas

  • Polymeric composites, Nanostructured materials