Fabrication of Superhydrophobic/Superoleophilic Surface and Study on Phase Behavior of Poly(N-isopropylacrylamide) in Solution or Solid State

• Main Authors: Tu, Cheng-Wei, 杜成偉
• Other Authors: Chang, Feng-Chih
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/00400505645292231055

博士 === 國立交通大學 === 應用化學系所 === 98 === The wetting behavior of solid surfaces by a liquid is a very important aspect of surface chemistry, which may have a variety of practical applications. Recent achievements in the construction of surfaces with special wettabilities, such as superhydrophobicity, superoleophilicity, superhydrophobicity/superoleophilicity, and others are presented. The control of the surface micro-/nanostructure and the chemical composition is critical for these special properties. In this thesis, we have developed a directly method to prepare a rough polystyrene surface consisting of micro-beads and nano-fibers mixed structure without any chemical modification. The mixed structure shows superhydrophobic and superoleophilic properties, and then it can be used to separate oil/water or used as an oil-sorbent. The development of biocompatible polymer is an important problem in the modern macromolecular engineering and gene delivery systems. Poly(N-isopropylacrylamide) (PNIPAM) is one of the best known biocompatible polymer which reveals thermo-responsive property with lower critical solution temperature (LCST) about 32 °C. This is a convenient temperature form the context of biomedical applications because it is below body temperature. We have synthesized poly(ethylene oxide-block-N-isopropylacrylamide) diblock copolymer (PEO-b-PNIPAM) by atom transfer radical polymerization. The α-cyclodextrin (α-CD) can form the inclusion complexes (ICs) with PEO-b-PNIPAM after selective threading of the PEO segment. The α-CD/PEO IC shows a long rod-like structure and stacks each other to form a hexagonally packed plate as evidenced by wide-angle X-ray diffraction (WAXD). Small-angle X-ray scattering (SAXS) data further reveals that the α-CD/PEO-b-PNIPAM IC self-assembled to long range ordered lamellar structure exhibiting alternating layers of the amorphous phase of unincluded PEO/PNIPAM and crystal phase of α-CD/PEO IC. The LCST for PNIPAM is affected by the nature of substituent groups, molar mass, co-solvent, salts and surfactants. We focus on the phase behavior of PNIPAM in the mixed solvent of D2O and tetrahydrofuran-d8 by Fourier transform infrared (FTIR) spectroscopy. The evolution of the coil-to-globule-to-coil transition at 25 °C was caused by complicated interactions in the PNIPAM THF-d8/D2O and PNIPAM. We believe that dehydration and aggregation of the hydrophobic groups are the major driving force, while the inter- and intra-chain hydrogen bond of PNIPAM and hydrogen bond between D2O and PNIPAM are the minor factor for the subsequent aggregation and the coil-to-globule transition.