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Now showing 1 - 9 of 9

Self-supporting Polymer from a POSS Derivative
(2011-06-16)
Cheng, Chih-Chia
;
Yen, Ying-Chieh
;
Chang, Feng-Chih
;
應用化學系
;
Department of Applied Chemistry
A new polyhedral oligomeric silsesquioxane macromer, octakis[N-(6-aminopyridin-2-yl)-undecanamide-10-dimethyl-siloxy]silsesquioxane (POSS-C11-Py), containing eight diaminopyridine arms, is able to self-assemble to form a physically crosslinked polymer-like structure with good mechanical properties (tensile strength = 46.1 MPa, tensile modulus = 0.58 GPa, elongation = 49.3%) through quadruple hydrogen bonding interactions between these arms. POSS-C11-Py is the first organic/inorganic supermolecule possessing polymer-like mechanical properties as a result of self-complementary interactions, providing a potential route toward the design and fabrication of polymer-like supramolecular materials.
Supramolecular aggregations through the inclusion complexation of cyclodextrins and polymers with bulky end groups
(2007-01-01)
Chan, Shih-Chi
;
Kuo, Shiao-Wei
;
She, Hwo-Shuenn
;
Lin, Ho-May
;
Lee, Hsin-Fang
Mono-polyhedral oligomeric sillsesquioxane-end capped poly(epsilon-caprolactone) (mPPCL) can form inclusion complexes (ICs) with alpha- and gamma-cyclodextrins (CDs) but not with beta-CD. These CD ICs have been characterized with X-ray diffraction, solid-state C-13 cross-polarization/magic-angle-spinning NMR spectroscopy, H-1 NMR spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscopy. The poly(epsilon-caprolactone) (PCL) chain of mPPCL is included within the channel provided by the CDs to form a columnar, crystalline structure. The PCL/CD ratios determined by H-1 NMR spectroscopy for the ICs with alpha- or gamma-CDs are higher than the stoichiometries because of the steric hindrance of the bulky polyhedral oligomeric silsesquioxane chain end and result in a fraction of the e-caprolactone units free from complexation with the CDs. On the basis of these analyses, we propose some possible structures for these CD/mPPCL ICs. (c) 2006 Wiley Periodicals, Inc.
Thermal properties of polystyrene nanocomposites formed from rigid intercalation agent-treated montmorillonite
(2007-07-15)
Yei, Ding-Ru
;
Fu, Hue-Kuan
;
Chang, Yu-Hsin
;
Kuo, Shiao-Wei
;
Huang, Jieh-Ming
Polystyrene (PS)/clay nanocomposites were prepared with two different new intercalation organophilic clays, the phosphonium salt (APP) and the ammonium 4-(4-adamantylphenoxy)-1-butanamine (APB) salts, by emulsion polymerization technique. X-ray diffraction and transmission electron microscopy were performed to characterize the layered structures of APB- and APP-treated polymer-clay nanocomposites, and both resulted in exfoliated structures. Molecular weights of PS obtained from these nanocomposites are slightly lower than the virgin PS formed under similar polymerization conditions. Coefficient of thermal expansion showed approximately a 44-55% decrease for APB- and APP-intercalated clay nanocomposites relative to the pure PS. Both T-g and thermal decomposition temperature of the PS component in the nanocomposite are higher than the virgin PS, implying that the presence of clay is able to enhance thermal stabilities of the PS. (c) 2007 Wiley Periodicals, Inc.
Novel nanocomposite of epoxy resin by introduced reactive and nanoporous material
(2007-12-01)
Yang, Chao-Chen
;
Chang, Feng-Chih
;
Wang, Yen-Zen
;
Chan, Chia-Ming
;
Lin, Chen-Lung
A reactive and nanoporous particle (OG) was introduced to UV-cured epoxy resin to form great low D-k material for electronic industrial. We expected the porous cage of OG to decrease the dielectric constant of UV-cured epoxy resin and multiple reactive functional groups (oxirane ring) of OG reacted with photoinitiator to increase the curing density of UV-cured epoxy resin. The glass transition temperatures (T-g) of epoxy increases with the increase of the OG content up to 10 phr due to the increase of crosslinking density. Excessive aggregation at highest OG content of 15 phr results in the reduced crosslinking density and T-g. The char yield of the composite increases with increase of OG content because stable Si and SiO2 are formed after thermal decomposition. The presence of OG results in the higher porosity and thus the lower dielectric constant.
Studies on thermal properties of PS nanocomposites for the effect of intercalated agent with side groups
(2008-03-03)
Fu, Huei-Kuan
;
Huang, Chih-Feng
;
Huang, Jieh-Ming
;
Chang, Feng-Chih
;
應用化學系
Poly styrene-layered silicate nanocomposites were prepared from three new organically modified clays by emulsion polymerization method. These nanocomposites were exfoliated up to 3 wt% content of pristine clay relative to the amount of polystyrene (PS). The intercalated agents C-20, C-20-4VB, and C-20-POSS intercalated into the galleries result in improved compatibility between hydrophobic polymer and hydrophilic clay and facilitate the well dispersion of exfoliated clay in the polymer matrix. Results from X-ray diffraction, TEM and Fourier transform infrared spectroscopy indicate that these intercalated agents are indeed intercalated into the clay galleries successfully and these clay platelets are exfoliated in resultant nanocomposites. Thermal analyses of polystyrene-layered silicate nanocomposites compared with virgin PS indicate that the onset degradation temperature ca. 25 degrees C increased and the maximum reduction in coefficient of thermal expansion (CTE) is ca. 40% for the C-20-POSS/clay nanocomposite. In addition, the glass transition temperatures of all these nanocomposites are higher than the virgin PS. (c) 2008 Elsevier Ltd. All rights reserved.
Synthesis and characterization of amorphous octakis-functionalized polyhedral oligomeric silsesquioxanes for polymer nanocomposites
(2008-08-26)
Sheen, Yuung-Ching
;
Lu, Chu-Hua
;
Huang, Chih-Feng
;
Kuo, Shiao-Wei
;
Chang, Feng-Chih
We have synthesized the polyhedral oligomeric silsesquioxane (POSS) derivatives OS-POSS and OA-POSS through the hydrosilylation of styrene and 4-acetoxystyrene, respectively, with octakis(dimethylsiloxy)-silsesquioxane (Q(8)M(8)(H)). We then prepared OP-POSS through acetoxyl hydrazinolysis of OA-POSS with hydrazine monohydrate. The chemical structures of these POSS derivatives were characterized using FTIR and H-1 NMR spectroscopy and MALDI-TOF mass spectrometry. Unlike Q(8)M(8)(H), which is crystalline, these three hydrosilylated POSS derivatives are liquids at 25 degrees C. Through DSC and XRD analyses, we found that they exhibit polymer-like glass transitions and amorphous halos. These octakis-functionalized POSS derivatives can be regarded as amorphous glasses possessing low glass transition temperatures, the values of which depend on the intermolecular interactions of their outer organic groups. To investigate the dispersion of these POSS derivatives in polymer nanocomposites, we blended OS-POSS, OA-POSS, and OP-POSS with polystyrene, poly(4-acetoxystyrene), and poly(4-vinylpyridine), respectively, and investigated the effects of the resulting intermolecular aromatic hydrophobic, dipole-dipole, and hydrogen-bonding interactions, respectively. Dipole-dipole interactions provided the best dispersion of OA-POSS in poly(4-acetoxystyrene), in which the POSS-polymer intermolecular interactions were of similar strength to the POSS-POSS interactions. (C) 2008 Elsevier Ltd. All rights reserved.
A simple approach toward low-dielectric polyimide nanocomposites: Blending the polyimide precursor with a fluorinated polyhedral oligomeric silsesquioxane
(2008-09-15)
Ye, Yun-Sheng
;
Yen, Ying-Chieh
;
Chen, Wen-Yi
;
Cheng, Chih-Chia
;
Chang, Feng-Chih
This article describes a new and simple method for preparing polyimide nanocomposites that have very low dielectric constants and good thermal properties: simply through blending the polyimide precursor with a fluorinated polyhedral oligomeric silsesquioxane derivative, octakis(dimethylsiloxyhexafluoropropyl) silsesquioxane (OF). The low polarizability of OF is compatible with polyimide matrices, such that it can improve the dispersion and free volume of the resulting composites. Together, the higher free volume and lower polarizability of OF are responsible for the lower dielectric constants of the PI-OF nanocomposites. This simple method for enhancing the properties of polyimides might have potential applicability in the electronics industry. (C) 2008 Wiley Periodicals, Inc.
Surface Modification of Gold Nanoparticles with Polyhedral Oligomeric Silsesquioxane and Incorporation within Polymer Matrices
(2009-04-15)
Kuo, Shiao-Wei
;
Wu, Yung-Chien
;
Lu, Chu-Hua
;
Chang, Feng-Chih
;
應用化學系
A new approach to achieve polymer-mediated gold ferromagnetic nanocomposites in a polyhedral oligomeric silsesquioxane (POSS)-containing random copolymer matrix has been developed. Stable and narrow distributed gold nanoparticles modified by 3-mercaptopropylisobutyl POSS to form Au-POSS nanoparticles are prepared by two-phase liquid-liquid method. These Au-POSS nanoparticles form partial particle aggregation by blending with poly(n-butyl methacrylate) (PnBMA) homopolymer because of poor miscibility between Au-POSS and PnBMA polymer matrix. The incorporation the POSS moiety into the PnBMA main chain as a random copolymer matrix displays well-dispersed gold nanoparticles because the POSS-POSS interaction enhances miscibility between gold nanoparticles and the PnBMA-POSS copolymer matrix. This gold-containing nanocomposite exhibits ferromagnetic phenomenon at room temperature. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 811-819, 2009
Preparation and Characterization of Epoxy/Polyhedral Oligomeric Silsesquioxane Hybrid Nanocomposites
(2009-10-01)
Huang, Jieh-Ming
;
Huang, Hui-Ju
;
Wang, Yu-Xiang
;
Chen, Wen-Yi
;
Chang, Feng-Chih
We have prepared epoxy/polyhedral oligomeric silsesquioxane (POSS) nanocomposites by photopolymerization from octakis(glycidylsiloxy)octasilsesquioxane (OG) and diglycidyl ether of bisphenol A. We used nuclear magnetic resonance, Raman, and Fourier transform infrared spectroscopies to characterize the chemical structure of the synthetic OG. Differential scanning calorimetry and dynamic mechanical analysis (DMA) revealed that the nanocomposites possessed higher glass transition temperatures than that of the pristine epoxy resin. Furthermore, DMA indicated that all of the nanocomposites exhibited enhanced storage moduli in the rubbery state, a phenomenon that we ascribe to both the nano-reinforcement effect of the POSS cages and the additional degree of crosslinking that resulted from the reactions between the epoxy and OG units. Thermogravimetric analysis revealed that the thermal stability of the nanocomposites was better than that of the pristine epoxy. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1927-1934, 2009

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