Browsing by Author "Hsiue, GH"

Now showing 1 - 11 of 11

Characterization and properties of new silicone-containing epoxy resin
(2000-07-01)
Wang, WJ
;
Perng, LH
;
Hsiue, GH
;
Chang, FC
;
應用化學系
A new epoxy monorner, triglycidyloxy phenyl silane (TGPS) has been synthesized. By curing of TGPS, Epon 828 and DER 732, with 4,4-diaminodiphonyl methane (DDM), the curing rate and conversion efficiency of these epoxy resins are in the order of TGPS > Epon 828 > DER 732. In the mixed epoxy system of TGPS/Epon 828/DDM, homogenous products are obtained from all proportions. In addition, the glass transition temperature of the blend decreases with increasing amount of TGPS from 140 to 100 degrees C. By using TGA in a Nz environment, the onset decomposition temperature of silicone-containing epoxy resin system of TGPS is 80 degrees C lower than that of Epon 828, and the decomposition of TGPS is a two-stage process with maxima weight loss rates at 330 and 430 degrees C, respectively. The first stage involves the breaking of the silicons-containing group in TGPS and the second-stage is carbonization. In the second stage of carbonization, the temperature for maximum weight loss rate is 15 degrees C higher than that of the Epon 828 in the first stage. This result indicates that the silicone-containing group is in favor of the carbonization mechanism and the solid char yield at 800 degrees C for TGPS is 40 wt%. Based on EDX analysis on the surface elements, the presence of Si and C is indicative of the above observation. In addition, the result by using TGA in an air environment shows that the silicon-containing carbon residue is superior in preventing oxidative burning. The high limiting oxygen index (LOI) of TGPS at 35 is considered as an excellent flame retardant in the epoxy system. (C) 2000 Elsevier Science Ltd. All rights reserved.
Chemical modification of dicyclopentadiene-based epoxy resins to improve compatibility and thermal properties
(2001)
Hsiue, GH
;
Wei, HF
;
Shiao, SJ
;
Kuo, WJ
;
Sha, YA
A. series of siloxane-containing epoxy resins was obtained by curing dicyclopentadiene-containing epoxy DG with the silicon-containing curing agents TS, DS, and AS. Curing behavior was studied using DSC, and the activation energies of the DG curing reaction with curing agents TA, DS, and AS were found to be 59, 80, and 157 KJ/mol. Meanwhile, the curing reaction of DG with diamines was found to be a first-order reaction using Arrhenius plots. In addition, thermal stability and the weight loss behavior of the cured polymers were studied via TGA. The silicon-containing resins displayed higher weight loss temperatures and higher char yields than the silicon-free resin. The activation energies of degradation ranged from 108 to 206 KJ/mol. The morphology of the cured pieces were investigated using SEM. The DG/TS and DG/DS are more compatible between the epoxy and the curing agents than DG/AS. The limited oxygen index (LOI) values of 31 to 34 for the DG-based resin confirmed the effectiveness of silicon-containing epoxy resins as flame retardants. (C) 2001 Elsevier Science Ltd. All rights reserved.
Ferroelectric liquid crystalline polymers based on mesogens with halogen-containing terminal groups
(2003-01-01)
Sha, YA
;
Hsiue, GH
;
Chiu, CH
;
Jeng, RJ
;
Tai, HC
A new series of halogen-containing side chain ferroelectric liquid crystal polymers was synthesized. Mesophases were characterized by differential scanning calorimetry, polarizing optical microscopy. X-ray diffraction and molecular simulation. The behaviour of the liquid crystalline phase was investigated with variation of chiral centres. spacer units and grafted ratios. It was found that the thermal stability and temperature range of the chiral smectic C phase decreased with increasing length of the oligo-oxyethylene spacer. and decreasing mesogenic group content. The bulky substituent attached to the chiral centre reduces molecular packing in smectic liquid crystal phases, which disturbs the orientation of the side chain liquid crystal polymer. Furthermore, the influence of molecular structure on electro-optical properties of FLCPs has been studied by broad band dielectric spectroscopy (from 0.1 to 1 x 10(6) Hz).
Molecular design of ferroelectric liquid crystalline polymers
(1995-12-01)
Hsu, CS
;
Hsiue, GH
;
應用化學系
;
Department of Applied Chemistry
The synthesis and characterization of several series of ferroelectric side-chain polymers were presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurement were used to determine their thermal transitions and analyze their anisotropic textures. The influence of polymer backbones, flexible spacers, mesogenic cores as well as chiral end groups on the mesomorphic properties of the polymers was discussed.
Nonviral gene carriers based on diblock copolymers of poly(2-ethyl-2-oxazoline) and linear polyethylenimine
(2006-05-17)
Hsiue, GH
;
Chiang, HZ
;
Wang, CH
;
Juang, TM
;
應用化學系
Diblock copolymers that consist of poly(2-ethyl-2-oxazoline) (PEOz) and linear polyethylenimine (LPEI) were prepared for use as nonviral gene carriers. The PEOz-b-LPEI copolymers were synthesized by coupling PEOz with LPEI in a thiol-disulfide exchange reaction between the sulfhydryl and pyridyl disulfide terminal groups. A polymer/DNA weight ratio (P/D) of over 12 was required to enable PEOz-b-LPEI to condense DNA completely. The DNA-condensing capability of the diblock copolymers was increased with increasing the hydrolytic degrees of the LPEI segment. The PEOz-b-LPEI polyplexes were stable in 150 mM NaCl aqueous solution and had a mean diameter around 190 nm, whereas BPEI and LPEI polyplexes formed large aggregates in the range 300-500 nm. In addition, these polyplexes exhibited the sensitivity to solution pH and were dissociated in the acidic buffers (pH <= 5.5). The results of in vitro cell viability and luciferase assay indicated that PEOz-b-LPEI showed not only low cytotoxicity but also high transfection efficiency in gene expression.
Novel phosphorus-containing dicyclopentadiene-modified phenolic resins for flame-retardancy applications
(2001-01-10)
Hsiue, GH
;
Shiao, SJ
;
Wei, HF
;
Kuo, WJ
;
Sha, YA
2- [4-(2-hydroxyphenyl)tricyclo[5.2.1.0(2,6)]dec-8-yl]phenol (HPTCDP) were prepared from dicyclopentadiene (DCPD) and phenol via Friedel-Crafts alkylation. DCPD-containing phenolic resin (DPR) was also synthesized by incorporating the DCPD-containing monomer HPTCDP with formaldehyde. DPR was further modified by grafting the phosphate group. The phosphorylation was confirmed by a Fourier transform infrared, P-31-NMR spectroscopy, and an element analysis. The phosphorus content in the DPR could be successfully tailored to give values of 3.46 to 7.79 wt % by varying the feeding ratios of the phosphorus group. The thermal stabilities of the phosphorus-containing polymers were identified by differential scanning calorimeter and thermogravimetric analysis. The glass transition temperature values were decreased as the content of phosphorus increased. High char yield 39-47 wt % in thermogravimetric analysis evaluation and limiting oxygen index values of 27 to 34 were found for all the phosphorylated phenolic resins. Such properties make these polymers highly promising for flame-retardant applications. (C) 2000 John Wiley & Sons, Inc.
Poly(2-hydroxyethyl methacrylate) film as a drug delivery system for pilocarpine
(2001-07-01)
Hsiue, GH
;
Guu, JA
;
Cheng, CC
;
應用化學系
;
Department of Applied Chemistry
This work investigates pilocarpine trapped in a matrix diffusion-controlled drug delivery system using hydrophilic inserts of Poly(2-hydroxyethyl methacrylate) (pHEMA) to ensure an increased bioavailability of pilocarpine and prolong the length of time in which the medication remains in the eyes of the test subjects. The physical and chemical properties of pilocarpine were investigated to elucidate the mechanism of drug-polymer interaction and the effect on drug release behavior of controlled release polymeric devices. In vitro release studies indicated that pilocarpine continued to be released from the inserts for a 24 h period. The results of intraocular pressure tests performed on albino rabbits were consistent with the observed in vitro behavior. The pressure decrease was significant for a period longer than 48 h. It confirms that the inserts, as sustainable releasing devices, are promising carriers for ophthalmic drug delivery systems. (C) 2001 Elsevier Science Ltd. All rights reserved.
Synthesis and biological properties of antitumor-active conjugates of ADR with dextran
(2002)
Guu, JA
;
Hsiue, GH
;
Juang, TM
;
應用化學系
;
Department of Applied Chemistry
Three kinds of polymeric adriamycin (ADR) conjugates of dextran were synthesized, namely a dextran-Gly-Leu-Gly-ADR (DGLGA) conjugate with a lysosomally degradable tripeptide spacer group, a dextran-Gly-Leu-Gly-ADR-galactosamine (DGLGA-Ga) conjugate with a targeting moiety of galactosamine on DGLGA, and a dextran-C6H10-ADR (DC(6)A) conjugate with a hexamethylen spacer group. The content of the ADR moiety in the polymeric-drug conjugate was about 3 mol%. Enzyme hydrolysis of DGLGA and DC(6)A was carried out by incubation with papain. The total amount of ADR released after 48 h was 43 mol% for DGLGA and less than 1 mol% for DC(6)A. In an in vitro cytotoxicity experiment. the DGLGA-Ga conjugate has higher cytotoxic efficacy than the other conjugates for incubation with Hep-3B cells and consequently. the capability of targeting hepatoma cells of the galactosamine residue was determined. In contrast, for the incubation with SiHa cells of these conjugates, there was no significant cytotoxicity effect. The in vivo cytotoxic efficacy of each conjugate (20 mg ADR equiv./kg) against CT-26 mice colon cells implanted subcutaneously in Balb-C mice was studied. The DGLGA conjugate generated the best therapeutic effect with the presence of long-term survival (LTS) at day 50 (2/6).
Synthesis and characterization of halogen-containing ferroelectric liquid crystals and side chain liquid crystalline polymers
(2001-03-01)
Hsiue, GH
;
Sha, YA
;
Hsieh, SJ
;
Jeng, RJ
;
Kuo, WJ
A new series of ferroelectric liquid crystals and side chain liquid crystalline polymers based on halogen-containing chiral centres has been synthesized. Chemical structures were analysed by NMR. Liquid crystal phases were characterized by differential scanning calorimetry, optical polarizing microscopy, and X-ray diffractometry. The behaviour of the liquid crystalline phases was investigated as a function of spacer units and differing terminal asymmetric moieties. It was found that phase transition temperatures decreased with increasing length of the oligooxyethylene spacer unit. Differing terminal asymmetric moieties led to differing mesophase phenomena. Furthermore, a wide temperature range (including room temperature) of a chiral smectic C phase was achieved.
Synthesis of dextran-(5-FU)-galactosamine conjugate through a tripeptide spacer group and its in vitro properties
(2000-07-01)
Guu, JA
;
Juang, TM
;
Hsiue, GH
;
Chiu, HC
;
應用化學系
In this study, conjugation of 5-fluorouracil (5-FU) and galactosamine with dextran via Glycyl-L-Leucyl-Glycine (Gly-Leu-Gly) tripeptidyl spacer was performed first by activation of dextran with p-nitrophenyl chloroformate, followed by aminolysis of Glycyl-L-Leucyl-Glycyl-5flurouracil (Gly-Leu-Gly-5-FU) and galactosamine with activated dextrans. Preparation of Gly-Leu-Gly-5-FU was carried out by sequential reactions of peptide synthesis in solution phases and coupling with 5-FU in the presence of diethylphosphoric cyanide. The release of 5-FU from the conjugates upon the exposure of polymeric prodrugs to papain implied that the attachment of 5-FU with the tripeptidyl spacer, Gly-Leu-Gly, was capable of being liberated by cathepsin B in lysosomes of targeted cells. The observation that the cytoxicity in vitro from the incubation of dextran-5-FU conjugate containing galactosamine residues with Hep-3B cells is higher than that in the void of galactosamine indicated the occurrence of specific binding of the targeting moieties with its receptors on cell membrane, leading to an enhanced cellular uptake of the conjugate via receptor-mediated endocytosis.
Synthesis, characterization, thermal and flame-retardant properties of silicon-based epoxy resins
(1999-08-15)
Hsiue, GH
;
Wang, WJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A new silicon-containing oxirane triglycidyl phenyl silane oxide (TGPSO) and its corresponding silicon-containing epoxy resins are synthesized and characterized. The activation energies of TGPSO curing reaction with various curing agents, including 4,4-diaminodiphenylmethane, 4,4-diaminodiphenylsulfone, and dicyanodiaminde, are found to be 180, 196.5, and 154 kJ/mol. The curing reaction of TGPSO with diamines is determined to be a first-order reaction through means of Arrhenius plots. The introduction of the silicon-containing group results in higher curing reactivity. This silicon-containing resin possesses higher char yield as well as higher limiting oxygen index (LOI = 35) than the commercial epoxy resins, confirming the usefulness of these silicon-containing epoxy resins as flame retardants. Char yields and LOI measurements demonstrate that incorporating silicon into epoxy resins is able to improve their flame retardancy. (C) 1999 John Wiley & Sons, Inc.