Browsing by Author "Xu, HY"

Now showing 1 - 11 of 11

Characterization of poly(vinyl pyrrolidone-co-isobutylstyryl polyhedral oligomeric silsesquioxane) nanocomposites
(2004-02-15)
Xu, HY
;
Kuo, SW
;
Huang, CF
;
Chang, FC
;
應用化學系
Poly(vinyl pyrrolidone-co-isobutyl styryl polyhedral oligomeric silsesquioxane)s (PVP-POSS) were synthesized by one-step polymerization and characterized 13 using FTIR, high-resolution H-1-NMR, solid-state C-13-NMR, Si-29-NMR, GPC, and DSC. The POSS content can be controlled by varying the POSS feed ratio. The T-g of the PVP-FOSS hybrid is influenced by three main factors: (1) a diluent role of the POSS in reducing the self-association of the PVP; (2) a strong interaction between the POSS siloxane and the PVP carbonyl, and (3) physical aggregation of nanosized POSS. At a relatively low FOSS content, the role as diluent dominates, resulting in a decrease in T-g. At a relatively high POSS content, the last two factors dominate and result in T-g increase of the PVP-POSS hybrid. (C) 2003 Wiley Periodicals, Inc.
Glass transition temperatures of poly(hydroxystyrene-co-vinylpyrrolidone-co-isobutylstyry1 polyhedral oligosilsesquioxanes)
(2002-09-01)
Xu, HY
;
Kuo, SW
;
Lee, JS
;
Chang, FC
;
應用化學系
A series of poly(hydroxystyrene-co-vinylpyffolidone-co-isobutylstyryl polyhedral oligosilsesquioxanes) (PHS-PVP-POSS) hybrid polymers with various POSS contents was prepared by free radical copolymerization of acetoxystyrene, vinylpyrrolidone with styrylisobutylpolyhedral oligosilsesquioxanes (POSS), followed by selective removal of the acetyl protective group. The POSS content of a hybrid polymer can be effectively controlled by varying the feed ratios of reactants. The T-g of the POSS hybrid increases with the POSS content of PHS-PVP-POSS hybrids. The mechanism of T-g enhancement in these PHS-PVP-POSS hybrids was investigated using DSC, FTIR and GPC. The formation of the physically cross-linked POSS in these hybrid polymers trends to restrict polymer chain motion and results in significant T-g increase. (C) 2002 Published by Elsevier Science Ltd.
Novel polymer electrolyte composed of poly(ethylene oxide), lithium triflate, and benzimidazole
(2004-01-15)
Chen, HW
;
Xu, HY
;
Huang, CF
;
Chang, FC
;
應用化學系
This work has demonstrated that the incorporation of benzimidazole derivatives, 2,2'-p-phenylene-bisindole (PPBI), enhances the ionic conductivity of a poly(ethylene oxide) (PEO)-based electrolyte by 20 times more than the plain system. Specific interactions among amino group, ethyl oxide, and lithium cation were investigated using differential scanning calorimetry (DSC), FTIR, and alternating current impedance. The DSC characterization confirms that the initial addition of PPBI is able to enhance the PEO crystallinity attributed to the interaction between the negative charge from the amino group and the lithium cation. Three types of complexes are present: complex I is present in the PEO phase, complex 11 resides at interphase, and complex III is located within the PPBI domain. Complex II plays the key role in stabilizing these two microstructure phases. FTIR spectra confirm that because of the presence of PPBI one is able to dissolve lithium salts more easily than in the plain electrolyte system and thus increase the fraction of free ions. (C) 2003 Wiley Periodicals, Inc.
Poly(acetoxystyrene-co-isobutylstyryl POSS) nanocomposites: Characterization and molecular interaction
(2002)
Xu, HY
;
Kuo, SW
;
Huang, CF
;
Chang, FC
;
應用化學系
The poly (acetoxy styrene-co-isobutyl styryl polyhedral oligomeric silsesquioxanes)s (PAS-POSS) were synthesized by free radical polymerization and characterized by FTIR, high resolution NMR, FTIR, GPC, and DSC. The results show that the POSS content can be controlled by varying the POSS feed ratios. The interactions between organic components and inorganic POSS core, and the effects of inorganic POSS core on the properties of the resulting hybrids were investigated by high resolution solid state C-13 NMR, Si-29 NMR and FTIR spectra. The results provide detailed understandings of the effects of POSS moiety on properties of hybrid polymers.
Preparations, thermal properties, and T-g increase mechanism of inorganic/organic hybrid polymers based on polyhedral oligomeric silsesquioxanes
(2002-11-05)
Xu, HY
;
Kuo, SW
;
Lee, JS
;
Chang, FC
;
應用化學系
A series of novel hybrid poly(acetoxylstyrene-co-isobutylstyryl-POSS)s (PAS-POSS) and poly(vinylpyrrolidone-co-isobutylstyryl-POSS)s (PVP-POSS) are synthesized and characterized. The POSS content in these hybrids can be controlled by varying the monomer feed ratio. The polyhedral oligosilsesquoixane (POSS) moiety can effectively increase the T-g of the resultant organic/inorganic hybrid polymer at a relatively high POSS content and produce the hybrid copolymer with narrower molecular weight distribution. The FTIR spectra are used to investigate the structure-property relationship of these hybrid polymers, and the T-g enhancement mechanism is discussed in detail.
Significant glass transition temperature increase based on polyhedral oligomeric silsequioxane (POSS) copolymer through hydrogen bonding
(2002-07-01)
Xu, HY
;
Kuo, SW
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A series of poly(vinylphenol-co-vinylpyrrolidone-co-isobutylstyryl polyhedral-oligosilsesquioxane (PVPh-co-PVP-co-POSS) copolymers were prepared by free radical copolymerization of acetoxystyrene, vinylpyrrolidone with POSS (PAS-co-PVP-co-POSS) following by selective removal of the acetyl protective group, and results in significant glass transition temperature increase. The thermal properties and hydrogen bonding of these copolymers were investigated by differential scanning calorimetry and fourier transfer infrared spectroscopy and good correlation between thermal behaviors and infrared spectroscopy results were observed.
Significant glass-transition-temperature increase through hydrogen-bonded copolymers
(2002-10-01)
Kuo, SW
;
Xu, HY
;
Huang, CF
;
Chang, FC
;
應用化學系
The role of hydrogen bonding in promoting intermolecular cohesion and higher glass-transition temperatures of polymer is a subject of longstanding interest. A series of poly(vinylphenol-co-vinylpyrrolidone) copolymers were prepared by the free-radical copolymerization of acetoxystyrene and vinylpyrrolidone; this was followed by the selective removal of the acetyl protective group, with corresponding and significant glass-transition-temperature increases after this procedure. The incorporation of acetoxystyrene into poly(vinylpyrrolidone) resulted in lower glass-transition temperatures because of the reduced dipole interactions in its homopolymers. However, the deacetylation of acetoxystyrene to transform the poly(vinylphenol-co-vinylpyrrolidone) copolymer enhanced the higher glass-transition temperature because of the strong hydrogen bonding in the copolymer chain. The thermal properties and hydrogen bonding of these two copolymers were investigated with differential scanning calorimetry and Fourier transform infrared spectroscopy, and good correlations between the thermal behaviors and IR results were observed. (C) 2002 Wiley Periodicals, Inc.
Star polymers via atom transfer radical polymerization from adamantane-based cores
(2004-03-29)
Huang, CF
;
Lee, HF
;
Kuo, SW
;
Xu, HY
;
Chang, FC
A series of novel multifunctional initiators derived from adamantane-based derivatives have been used in the syntheses of various styrenic and (meth)acrylic star polymers by atom transfer radical polymerization (ATRP). Conditions were identified in each system to produce star polymers with nearly monomodal molecular distributions. These synthesized star polymers have glass transition temperatures similar to those known for high-molecular-weight linear polymers. We obtained a series of adamantane-contained star polymers covering a wide range of molecular weights by adjusting the monomer-to-initiator ratio and the solvent polarity. Because of reaction heterogeneity and inevitable termination processes, the occurrence of star-star coupling led to a lower than predicted molecular weight polydispersity. When hydrolyzed from their cores by NaOH, the values of Mw of the arms of the PMMA star polymer did not change with reaction time, at least for the first 48 h of the reaction, which implies that no significant PMMA hydrolysis occurs within this interval of time. (C) 2004 Elsevier Ltd. All rights reserved.
Synthesis and characterization of novel organic/inorganic hybrid polymers containing polyhedral oligosilsesquioxanes
(2005-01-01)
Xu, HY
;
Gao, XY
;
Guang, SY
;
Chang, FZ
;
應用化學系
Hybrid polymers, poly(vinyl pyrrolidone-co-isobutyl styryl polyhedral oligomeric silsesquioxanes)s (PVP-POSS) were synthesized by one step polymerization and characterized using GPC and DSC. Addition of POSS significantly increases the Tg of polyvinylpyrrolidone at a fair high POSS content and obtained high molecular weight polymers with very narrow molecular distribution. The POSS content in the resulted hybrids can be controlled by varying the POSS feed ratio.
Thermal properties and hydrogen bonding in polymer blend of polybenzoxazine/poly(N-vinyl-2-pyrrolidone)
(2003-04-01)
Su, YC
;
Kuo, SW
;
Yei, DR
;
Xu, HY
;
Chang, FC
The thermal properties and hydrogen bonding behavior of B-a type polybenzoxazine (PBZZ)/PVP blends were investigated by DSC and FIFIR. The DSC result shows a single T-g over the entire compositions and a large positive deviation based on Kwei equation was observed in the T-g versus composition diagram, implying that strong hydrogen bonding interaction exists between PBZZ and PVP segments. The strength of hydrogen bonding interaction is in the order of inter-association between the hydroxyl group of PBZZ and the carbonyl group of PVP (K-A = 594 L mol(-1)) > self-association between the hydroxyl group of pure PBZZ (K-B = 72.6 L mol(-1)) > inter-association between the hydroxyl and the Mannich-based bridge of pure PBZZ (K-C < 10 L mol(-1)). Good correlation between DSC and FIFIR analysis were observed. (C) 2003 Elsevier Science Ltd. All rights reserved.
Thermal properties, miscibility and specific interactions in comparison of linear and star poly(methyl methacrylate) blend with phenolic
(2004-08-05)
Huang, CF
;
Kuo, SW
;
Lin, HC
;
Chen, JK
;
Chen, YK
A series of miscible linear and star poly(methyl methacrylate) (PMMA)/phenolic blends with different compositions have been prepared. T(g)s of both systems are negative derivation from the average values, implying that the self-association interaction is stronger than the inter-association interaction between linear or star PMMA with phenolic. The proton spin-lattice relaxation time in the rotating frame (T-1rho(H)) determined by high resolution solid state C-13 NMR indicates single composition dependent T-1rho(H) from all blends, implying a good miscibility with chain dynamics on a scale of 1-2 nm. However, T(1rho)(H)s of star PMMA/phenolic blends are relatively smaller than those of linear PMMA/phenolic blends, implying that the degree of homogeneity of star PMMA/phenolic blends is higher than those of linear PMMA/phenolic blends. According to FT-IR analyses, the above results can be rationalized that the hydrogen-bonding interaction of the star PMMA/phenolic blends is greater than the corresponding linear PMMA/phenolic blends. (C) 2004 Elsevier Ltd. All rights reserved.