• Title/Summary/Keyword: hydrophilic polymer

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Studies on thermal and swelling properties of Poly (NIPAM-co-2-HEA) based hydrogels

  • Shekhar, Suman;Mukherjee, M.;Sen, Akhil Kumar
    • Advances in materials Research
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    • v.1 no.4
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    • pp.269-284
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    • 2012
  • Thermoresponsive hydrogels based on N-Isopropylacrylamide (NIPAM) and 2-Hydroxyethylacrylate (HEA) were prepared by free radical polymerization. The hydrogels were characterized by elemental (CHN) analysis, differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). DSC thermogram showed two endothermic transitions which are due to hydration of water present in different environments. One near $0^{\circ}C$ called melting transition of ice and was used to calculate the quantitative determination of the amounts of freezing and non freezing water. The other transition above the ambient temperature was due to the combination of hydrophobic hydration and hydrophilic hydration which changes with the copolymer compositions. Swelling and deswelling studies of the hydrogels were carried out using the aqueous media, salt and urea solutions. The experimental results from swelling studies revealed that copolymers have lower rates of swelling and deswelling than the homopolymer.

Pore-network Study of Liquid Water Transport through Multiple Gas Diffusion Medium in PEMFCs (고분자 연료전지의 다공성층 내에서의 액상수분 이동에 관한 공극-네트워크 해석 연구)

  • Kang, Jung-Ho;Lee, Sang-Gun;Nam, Jin-Hyun;Kim, Charn-Jung
    • 한국전산유체공학회:학술대회논문집
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    • 2011.05a
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    • pp.46-53
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    • 2011
  • Water is continuously produced in polymer electrolyte membrane fuel cell (PEMFC), and is transported and exhausted through polymer electrolyte membrane (PEM), catalyst layer (CL), microporous layer (MPL), and gas diffusion layer (GDL). The low operation temperatures of PEMFC lead to the condensation of water, and the condensed water hinders the transport of reactants in porous layers (MPL and GDL). Thus, water flooding is currently one of hot issues that should be solved to achieve higher performance of PEMFC. This research aims to study liquid water transport in porous layers of PEMFC by using pore-network model, while the microscale pore structure and hydrophilic/hydrophobic surface properties of GDL and MPL were fully considered.

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Preparation of PET Nanocomposites: Dispersion of Nanoparticles and Thermal Properties

  • Her, Ki-Young;Kim, Dae-Heum;Lim, Soon-Ho
    • International Journal of Precision Engineering and Manufacturing
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    • v.9 no.4
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    • pp.71-73
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    • 2008
  • The development of polymer/inorganic nanocomposites has attracted a great deal of interest due to the improved hybrid properties derived from the two different components. Various nanoscale fillers have been used to enhance polymer mechanical and thermal properties, such as toughness, stiffness, and heat resistance. The effects of the filler on the final properties of the nanocomposites are highly dependent on the filler shape, particle size, aggregate size, surface characteristics, polymer/inorganic interactions, and degree of dispersion. In this paper, we describe the influence of different $CaCO_3$ dispersion methods on the thermal properties of polyethylene terephthalate (PET)/$CaCO_3$ composites: i.e., the adsorption of $CaCO_3$ on the modified PET surface, and the hydrophobic modification of the hydrophilic $CaCO_3$ surface. We prepared PET/$CaCO_3$ nanocomposites using a twin-screw extruder, and investigated their thermal properties and morphology.

Drug Release Characteristics of Crosslinked Poly(alkylene oxide) Hydrogels (가교된 폴리 알킬렌 옥사이드 하이드로겔의 약물방출 특성)

  • Kim, Shin-Jeong;Lee, Seung-Jin
    • Journal of Pharmaceutical Investigation
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    • v.21 no.2
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    • pp.91-95
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    • 1991
  • Polyethylene glycol, polypropylene glycol and block copolymer of ethylene glycol and propylene glycol were crosslinked by triisocyanate to form water swellable, rubbery polymer. The equilibrium swelling of the hydrogels ranged from 3% to 60% according to the hydrophobic-hydrophilic properties of the prepolymers. Model drugs, sodium salicylate and prednisolone were incorporated in the polymer matrices by swelling loading. Physical properties of the drugs affected the drug release mechanisms due to the change in the swelling behaviors of the polymeric devices. Zero order release was observed in the case of relatively hydrophobic polymer matrices.

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Performance of Anion Charged Copoly(1,2,4-benzenetricarboxylate/bis[4-(3-aminophenoxy)phenyl]sulfone/3,3',4,4'-benzophenone tetracar boxylate/1,2,3,4-butanetetracerboxylate) Ultrafiltration Membranes (음이온성 Copoly(1,2,4-benzenetricarboxylate/bis[4-(3-aminophenoxy)phenyl]sulfone/3,3',4,4'-benzophenonetetracarboxylate/1,2,3,4-butanetetracerboxylate) 한외여과막의 투과특성)

  • Jeon, Jong-young
    • Journal of the Korean Society of Industry Convergence
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    • v.12 no.4
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    • pp.193-202
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    • 2009
  • In the preparation of anion charged asymmetric ultrafiltration membranes by the conventional phase inversion method, several variables could be adjusted to control membrane permeations. The anion charged materials and its original polymer have good solubility in N-methyl-2-pyrrolidone. The membranes having a hydrophilic property were less fouled the membrane prepared from the original polymer. The preparation conditions, operation conditions, and hydrophilicity of polymer have played an important role in determining the permeation properties of membranes.

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Swelling Controlled Drug Release from Acrylamide-Styrene Copolymer Hydrogels (Acrylamide-Styrene Copolymer 하이드로겔로부터의 수팽윤 속도조절에 의한 약물 방출)

  • Kim, Min-Kyoung;Lee, Seung-Jin
    • Journal of Pharmaceutical Investigation
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    • v.19 no.4
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    • pp.173-178
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    • 1989
  • Drug release rates from copolymer hydrogels were controlled by their hydrophilic-hydrophobic balances. As a model copolymer hydrogel, poly(acrylamide-co-styrene) was synthesized at different monomer composition. Release mechanisms of propranolol-HCI from the copolymer matrices were investisated. Swelling rates of the copolymer hydrogels retarded as their hydrophobicity increased. Swelling kinetics of the copolymer hydrogels regulated drug release rates via polymer relaxation controlled release mechanisms. Zero order drug release could thus be achieved within certain periods.

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A Study on optical glass polishing using Fixed Abrasive Pad (고정입자패드를 이용한 광학 유리 폴리싱에 관한 연구)

  • 최재영;김초윤;박재홍;정해도
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.78-81
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    • 2003
  • Polishing Processes are widely used in the glass, optical, die and semiconductor industry and are conventionally carried out using abrasive slurry and a polishing pad. But abrasive slurry process has a weak point that is high cost of handling of used slurry and hard controllability of slurry. Recently, some researches have attempted to solve these problems and one method is the development of a fixed abrasive pad. FAP has a couple of advantages including clean environment, lower CoC, easy controllability and higher form accuracy. But FAP also has a weak point that is need of dressing because of glazing and loading. The paper introduces the basic concept and fabrication technique of FAP using hydrophilic polymers with swelling characteristics in water and explains the self-conditioning phenomenon. Experimental results demonstrate to achieve nano surface roughness of soda lime glass for optical application

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Swelling Controlled Delivery of Antibiotic from a Hydrophilic Macromolecular Matrix with Hydrophobic Moieties

  • Shukla, Sandeep;Bajpai, Anil Kumar;Bajpai, Jaya
    • Macromolecular Research
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    • v.11 no.4
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    • pp.273-282
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    • 2003
  • A hydrophilic macromolecular network containing hydrophobic moieties has been prepared by free radical copolymerization of acrylamide and styrene in the presence of poly(vinyl alcohol) (PVA) and its potential as controlled drug delivery carrier was evaluated with tetracycline as a model antibiotic drug. The amount of drug was assayed spectrophotometrically. The network was characterized by optical microscopy, infra-red spectroscopy and structural parameters such as average molecular weight between cross1inks ($M_c$), cross1ink density (q) and number of elastically effective chains ($V_e$) were evaluated. It was found that with increasing concentration of PVA, ST and MBA in the hydrogel, the release rate initially increases but after definite concentrations of the above components the release rate falls. In the case of AM, release rate constantly decreases with increasing AM concentration in the hydrogel.

Synthesis and Microphase Separation of Biodegradable Poly($\varepsilon$-caprolactone)-Poly(ethylene glycol)-Poly($\varepsilon$-caprolactone) Multiblock Copolymer Films

  • You, Jae-Ho;Choi, Sung-Wook;Kim, Jung-Hyun;Kwak, Young-Tae
    • Macromolecular Research
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    • v.16 no.7
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    • pp.609-613
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    • 2008
  • Poly($\varepsilon$-caprolactone)-poly(ethylene glycol)-poly($\varepsilon$-caprolactone) (PCL-PEG-PCL) multiblock copolymers at various hydrophobic-hydrophilic ratios were successfully synthesized by the chain extension of triblock copolymers through isocyanate (hexamethylene diisocyanate). Biodegradable films were prepared from the resulting multiblock copolymers using the casting method. The mechanical properties of the films were improved by chain extension of the triblock copolymers, whereas the films prepared by the triblock copolymers were weak and brittle. Atomic force microscopy (AFM) of the multiblock copolymer film showed that the hydrophilic PEG had segregated on the film surface. This is consistent with the observed contact angle of the films.

Dissolution Enhancement of Fenticonazole Nitrate from Hydrophilic Polymer Solid Dispersions (친수성 고분자와의 고체분산체로부터 질산펜티코나졸의 용출 증가)

  • Kim, Young-Il;Kim, Seung-In;Choi, Jae-Yoon
    • Journal of Pharmaceutical Investigation
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    • v.19 no.2
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    • pp.109-116
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    • 1989
  • Solid dispersion of fenticonazole nitrate (FN) with poloxamer 407, polyethylene glycol 6000, povidone (K-90) were prepared by the solvent method. To characterize the state of the drug in solid dispersions, the x-ray diffractometry and differential scanning calorimetry were carried out. The identification of these systems suggested that FN in the poloxamer 407 system remained in crystalline state, and the drug in the PVP system was amorphous. A marked increase in the dissolution rate of FN was attained by dispersing the drug in the hydrophilic polymers used, and the dispersion with poloxamer 407 was superior to the other two carriers in releasing the drug into solution.

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