Showing papers by "Suat Hong Goh published in 2003"
TL;DR: Scanning electron microscope studies revealed that the CyA-BSA-loaded double-walled POE/PLGA microspheres yielded a more porous surface and PLGA shell than those without BSA, which would make an interesting device for controlled delivery of therapeutic agents.
96 citations
TL;DR: In this paper, single and double-C60-end-capped poly(ethylene oxide)s (PEOs) were prepared by reacting azido-terminated PEO with C60.
Abstract: Single- and double-C60-end-capped poly(ethylene oxide)s (PEOs) were prepared by reacting azido-terminated PEO with C60. The aggregation behavior of these polymers in THF and water was studied by gel permeation chromatography, static and dynamic laser light scattering, and transmission electron microscopy. The solvent polarity, the amount of C60, and the length of PEO segments significantly affect the conformation and the size distribution of aggregates or clusters. The aggregation number of single-C60-end-capped PEO exceeds 104, far larger than nonionic surfactants consisting of PEOs end-capped with paraffinic chains due to the stronger hydrophobic character of C60. Single-C60-end-capped PEO forms much larger aggregates than those of double-end-capped PEOs, possibly due to the relatively higher mobility of the former polymer. The PEO chain length of the double-C60-end-capped PEO controls the aggregate conformation and particle size distribution. It is believed that large aggregation complex comprises seve...
95 citations
TL;DR: In this paper, in situ functionalized multi-walled carbon nanotube (MWNT)/Phenoxy composites were prepared by melt mixing Phenoxy with MWNT and 1-(aminopropyl)imidazole (NIm).
78 citations
TL;DR: In this article, a biodegradable poly(amino ester) containing secondary and tertiary amines in the backbones was obtained from the Michael addition polymerizations of trifunctional amine monomers with diacrylates, and showed high transfection efficiency for the delivery of DNA comparable to those of polyethylenimine (PEI) and low cytotoxicity.
65 citations
TL;DR: In this paper, a two-arm fullerene-containing poly(ethylene oxide) (PEO) was synthesized through isocyanate-hydroxy condensation reaction with fullerenol as a molecular core and characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectrograph, thermogravimetry, and matrix-assisted laser desorption ionization time of flight mass spectrometry.
63 citations
TL;DR: For the first time, the permeation experiments of CO 2 are carried out on ultra-thin dense polyimide films (0.5-1.8μm).
62 citations
TL;DR: It was found that compared to the neat POE or PLGA microspheres, distinct degradation mechanism was achieved in the double walled POE/PLGA micro Spheres system and kept more than 32% of its initial molecular weight over a period of 7 weeks.
57 citations
TL;DR: In this article, double-C 60 -end-capped poly(ethylene oxide) (FPEOF) was reinforced with acid-treated multi-walled carbon nanotubes (MWNTs).
44 citations
TL;DR: In this article, double-C60-end-capped poly(ethylene oxide) (FPEOF) exhibited concentration-dependent optical limiting behavior in toluene, THF, and water.
Abstract: Double-C60-end-capped poly(ethylene oxide) (FPEOF) exhibited concentration-dependent optical limiting behavior in toluene, THF, and water. Its performance was not only inferior to C60−toluene solution with similar C60 concentration, but its linear transmittance was also remarkably lowered by the aggregation of C60 in the solutions. Optical limiting studies with poly(ethylene oxide)/FPEOF blends suggested the significance of bimolecular excited-state processes (such as the formation of C60 excimers) to the optical limiting performance of FPEOF at 532 nm. Although an aqueous multiwalled nanotube (MWNT) suspension showed only weak optical limiting actions toward laser at 532 nm operating at 20 Hz, its mixing with FPEOF solution resulted in enhanced optical limiting responses. FPEOF/MWNT composites also exhibited optical limiting responses at 1064 nm.
42 citations
TL;DR: In this paper, the miscibility and interactions in blends and complexes of poly(4-methyl-5-vinylthiazole) (PMVT) with poly(pvinylphenol), poly(acrylic acid) (PAA) and poly(vinylphosphonic acid)(PVPA) were studied.
39 citations
TL;DR: The study on the inclusion complexes of perfluorinated oligomers (F-oligomers) with CDs will show that oligo(tetrafluoroethylene oxide-) will be shown to have different conformations compared to hydrogen.
Abstract: Moreover, the larger radius of fluorine compared tohydrogen leads to larger cross-sectional areas anddifferent conformations of the fluorinated oligomers.Thus, it is of interest to investigate the complexationbehavior between fluorinated oligomers and CDs. Herewe report our study on the inclusion complexes ofperfluorinated oligomers (F-oligomers) with CDs. It willbe shown that oligo(tetrafluoroethylene oxide-
TL;DR: Double-C 60 -end-capped poly(ethylene oxide) (PEO) possesses good mechanical properties arising from a network-like structure due to the aggregation of C 60.
TL;DR: In this article, a series of trifluoromethyl groups-containing nanocomposites films were made by thermal curing of respective formulations containing fluoropoly(ether-amic acid) (6F-PEAA), synthesized from 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride and 4,4'-bis (4-aminophenoxy)diphenyl sulfone (p-SED) at temperature from RT to 350 °C.
Abstract: A series of fluoropoly (ether-imide) (6F-PEI), and [6F-PEI/montmorillonite (MMT) clay) nanocomposites films were made by thermal curing of respective formulations containing fluoropoly(ether-amic acid) (6F-PEAA), synthesized from 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 4,4'-bis(4-aminophenoxy)diphenyl sulfone (p-SED), and increasing concentration of p-SED treated montmorillonite clay (modified MMT clay) at temperature from RT to 350 °C. These films showed excellent solvent resistance as well as very good thermal stability, and increased glass transition (T g ) values with increasing % clay. In addition, these trifluoromethyl groups-containing nanocomposites films showed sharp lowering of coefficient of thermal expansion (CTE) by 22%. Furthermore, they exhibited increased long-term thermo-oxidative stability (TOS), with % weight retention in the range of 86 to 92% in isothermal heating at 300°C for 300 h in air, reduced water absorption at 100 RH at 50°C in the range of 0.5 to 1.15%. These data are still much lower than those of neat ULTEM ® 1000 and Kapton® H film. The modulus of elasticity is on an average 38% higher for the nanocomposite films relative to neat fluoropoly(ether-imide) (6FDA+p-SED), and above non-fluorinated polyimide films. The surface energy measurement by One-Liquid and Two-Liquid method showed a comparable trend of decreasing contact angle. For the nanocomposite films having 15% hydrophobic clay, the contact angle decreased by 21 and 20% for DI-water and formamide, respectively. The surface energy increase was in the range of 8.21 -8.54 mJ/m 2 .
TL;DR: In this paper, the nonlinear optical properties of composites which consist of mono-functional 1,2-dihydro-1,2methanofullerene[60]-61-carboxylic acid (FCA) and poly(styrene-co-4vinylpyridine) were studied.
TL;DR: In this paper, the nonlinear optics and optical limiting properties of materials based on multifunctional fullerenol and poly (styrene-co-4-vinylpyridine) matrix were studied using 7 ns pulses of nanosecond laser operating at 532 nm wavelength.
Abstract: The nonlinear optics and optical limiting properties of materials based on multifunctional fullerenol and poly (styrene-co-4-vinylpyridine) matrix were studied using 7 ns pulses of nanosecond laser operating at 532 nm wavelength. The observed imaginary and real parts of third order susceptibility of the fullerenol/polymer composite are found to be lower than that of its parent C60. The optical limiting performances of fullerenol and fullerenol incorporated with poly(styrene-co-4-vinylpyridine) have been proved to be poorer than that of C60 due to their higher limiting thresholds. Concentration dependence of poly(styrene-co-4-vinylpyridine) containing 32 mol% has been mainly contributed to the optical limiting performance of fullerenol.
TL;DR: In this paper, it was shown that poly(methylthiomethyl methacrylate) is miscible with poly(vinyl alcohol) (PVA) over the whole composition range as shown by the existence of a single glass transition temperature in each blend.
TL;DR: In this paper, N,N-dimethylformamide (DMF) and ethanol solutions were used to produce poly(acrylic acid) and poly(p-vinylphenol) (PVPh) blends.
Abstract: Blends of poly(acrylic acid) (PAA) and poly(p-vinylphenol) (PVPh) were prepared from N,N-dimethylformamide (DMF) and ethanol solutions. The DMF-cast blends exhibited single Tg's, as shown by modulated differential scanning calorimetry, whereas the ethanol-cast blends had double Tg's. Fourier transform infrared spectroscopy showed that there was a specific interaction between PAA and PVPh in the DMF-cast blends. The single-Tg blends cast from DMF showed single-exponential decay behavior for the proton spin–lattice relaxation in both the laboratory frame and the rotating frame, indicating that the two polymers mixed intimately on a scale of 2–3 nm. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 789–796, 2003
TL;DR: In this paper, the surface properties of C60-containing poly(ethyl methacrylate)s (PEMA-C60) and their blends with PEMA were investigated by attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, and time-of-flight secondary ion mass spectrometry.
Abstract: The surface properties of C60-containing poly(ethyl methacrylate)s (PEMA-C60) and their blends with poly(ethyl methacrylate) (PEMA) were investigated by attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, time-of-flight secondary ion mass spectrometry, and contact-angle measurements. The polymer surface becomes more hydrophobic with increasing C60 content in the polymer. The PEMA-C60/PEMA blends show the surface enrichment of PEMA-C60. There is a good correlation between the surface hydrophobicity and the surface enrichment of PEMA-C60.
TL;DR: In this article, a multi-walled carbon nanotube (MWNT)/poly(acrylic acid)-C n TAB (n = 16, 14, 12) complex was synthesized and the dynamic mechanical properties of these complexes have been studied using DMA.
TL;DR: A series of novel liquid-crystalline polymer (LCP) systems, including a heterocyclic 2,5-thiophene unit, were synthesized and studied using a modified thin-film polymerization method as part of a continuing investigation of molecular structural effects on liquid crystallinity as mentioned in this paper.
Abstract: A series of novel liquid-crystalline polymer (LCP) systems, including a heterocyclic 2,5-thiophene unit, were synthesized and studied using a modified thin-film polymerization method as part of a continuing investigation of molecular structural effects on liquid crystallinity. The monomers used in the reaction included p-acetoxybenzoic acid (ABA)/2,6-acetoxynaphtholic acid (ANA), 4,4′-biphenol (BP)/4,4′-diacetoxybiphenyl (DABP)/p-acetoxyacetanilide (AAA), and 2,5-thiophenedicarboxylic acid (TDA). Polarizing light microscopy and Fourier transform infrared spectra were used to study, in situ record the evolution of morphological change in the thin-film polymerization process, and confirm the occurrence of polymerization. Experimental results indicated that monomer structure and composition as well as temperature influence the formation of the liquid crystalline (LC) phase greatly and revealed that 2,5-thiophene structure is a viable mesogenic core unit. It is more effective than isophthalic acid (IA) in assisting in the LC formation as polymers containing TDA have a better developed LC phase and lower critical ABA content than those with IA. Stripe texture was observed in the ANA/DABP/TDA system, possibly due to the structural characteristics and matching of the monomers. The decrease of isotropic round areas in the LC phase and the annihilation between two pairs of defects with reaction time were also studied.
TL;DR: In this paper, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD) were used to study the hydrogen-bonding interaction and miscibility between poly(2-vinylpyrdine) (P2VPy) and five bisphenols.
Abstract: Hydrogen-bonding interaction and miscibility between poly(2-vinylpyrdine) (P2VPy) and five bisphenols are studied by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD). It is found that the miscibility behavior strongly depends on the flexibility of the bisphenol molecules. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1137–1143, 2003
TL;DR: In this paper, the texture evolution when synthesizing a novel liquid crystalline polymer (LCP) system based on Sumikasuper® LCPs was studied using the thin film polymerization approach.
Abstract: Using the thin film polymerization approach, we have studied the texture evolution when synthesizing a novel liquid crystalline polymer (LCP) system based on Sumikasuper® LCPs. The main monomers used were p-acetoxybenzoic acid (ABA), 4,4′-biphenol (BP), isophthalic acid (IA), phthalic acid (PA) and terephthalic acid (TA). Polarizing optical microscopy (POM), FTIR, X-ray diffraction (XRD) and atomic force microscopy (AFM) were employed to study the thin film polymerization process and characterize the products. The generation and evolution of liquid crystal phases were monitored; the results revealed that there exists a composition range for the monomers to react and form liquid crystal materials. The critical temperature for LC formation in ABA/BP/IA system decreased with increasing ABA content. FTIR results confirmed the formation of polymers. AFM investigation suggested a similar process of morphological change to that observed using POM. An increasing surface roughness of the thin films with the progre...
TL;DR: In this article, the supramolecular side chain liquid crystalline polymers (SCLCPs) based on poly(3-carboxypropylmethylsiloxane-co-dimethylsiloxanes) were studied using differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction, and were found to exhibit smectic A phases with focal-conic textures.
Abstract: Supramolecular side chain liquid crystalline polymers (SCLCPs) based on poly(3-carboxypropylmethylsiloxane-co-dimethylsiloxane) (PSIX, X=100, 76, 60, 41 or 23, denoting the mole percentage of 3-carboxypropylmethylsiloxane unit in the polymer) and stilbazole derivatives have been obtained through intermolecular hydrogen bonding (H-bonding) interactions between the carboxylic acid and the pyridyl moieties. The formation of H-bonding and self-assembly results in the formation of new mesogenic units, in which H-bonds function as molecular connectors. FTIR shows the existence of H-bonding in the complexes. The polymeric complexes behave as single component liquid crystalline polymers and exhibit stable and enantiotropic mesophases. The liquid crystalline properties of the supramolecular SCLCPs were studied using differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction, and were found to exhibit smectic A phases with focal-conic textures. The thermal stability of the SCLCP increase...