• Computers and Concrete
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• 제18권2호
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• pp.279-295
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• 2016

A new innovative composite material is textile reinforced cementitious composite (TRCC). To achieve high flexural performance researchers suggest polymer modification of TRCC matrices. In this study, nine ready mix repair mortars commonly used in construction industry and the production of TRCC elements were examined. Mechanical properties such as compressive and flexural strength, drying shrinkage were studied. Being a significant durability concern, alkali silica reaction tests were performed according to related standards. Results showed that, some ready repair mortar mixes are potentially reactive due to the alkali silica reaction. Two of the ready mortar mixes labelled as non-shrinkage in their technical data sheets showed the highest shrinkage. In this experiment, researchers designed new matrices. These matrices were fine grained concretes modified with polymer additives; latexes and redispersible powders. Two latexes and six redispersible powder polymers were used in the study. Mechanical properties of fine grained concretes such as compressive and flexural strengths were determined. Results showed that some of the fine grained concretes cast with redispersible powders had higher flexural strength than ready mix repair mortars at 28 days. Matrix composition has to be designed for a suitable consistency for planned production processes of TRCC and mechanical properties for load-carrying capacity.

• 대한화학회지
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• 제37권4호
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• pp.378-389
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• 1993

합성 polypeptide인 poly(γ-benzyl-L-glutamate)[PBLG]를 A-segment로 하고, polyoxypropylene(POP)를 B-segment로 하는 AB 형태 블록공중합체와 polypropyleneglycol을 B-segment로 하는 ABA 형태 블록공중합체를 합성한 후, 이들 공중합체의 생식 호르몬인 progesterone, estrone, estradiol, testosterone의 고분자 매트릭스를 제조하여 이들 스테로이드의 방출량의 변화를 연구하였다. PBLG-POP1와 PBLG-POP2의 매트릭스에서의 progesterone, estradiol 및 testosterone 방출속도와 ABA 형태의 GPG1 공중합체에서의 progesterone, estrone 및 testosterone 방출속도가 염기성용액보다 산성용액에서 더 빠름을 보았다. 한편 PBLG-POP1와 PBLG-POP2의 매트릭스에서의 estrone 그리고 ABA 형태의 GPG1의 매트릭스에서의 estradiol의 방출속도는 산성용액에서 보다 중성 및 염기성용액에서 더 빨랐다. 서로 다른 매트릭스에서의 방출차이는 GPG1 > PBLG-POP1 > PBLG-POP2이며, 방출속도는 스테로이드의 분자량에 반비례함을 보였다.

• Journal of Pharmaceutical Investigation
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• 제19권2호
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• pp.87-92
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• 1989

The multilayered monolithic type transdermal delivery device has been designed and analyzed by a numerical analysis. The device consists of three layered polymer matrices which posess the different diffusion parameters, respectively. The purpose of this study was to design an ideal transdermal drug delivery device which is capable of initial burst and zero order release later on. Numerical modelings were simulated for a dispersed and a dissolved multilayered monolithic system. The results showed that the dispersed multilayered monolithic system could meet the requirements for an ideal transdermal delivery device.

• Journal of Pharmaceutical Investigation
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• 제24권4호
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• pp.257-263
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• 1994

The interpenetrating polymer networks (IPNs) of polyacrylic acid (PAA)-polyethylene glycol (PEG) were synthesized via crosslinking of PEG and simultaneous free radical polymerization of PAA. The equilibrium swelling of the IPNs matrices, ranged from 40% to 95%, was varied to a great extent as compared with PAA homopolymer due to the interpolymer interaction between PAA and PEG. The drug release kinetics of drug loaded matrices was significantly affected by the charge of drugs as well as interpolymer complexation.

• Advanced Composite Materials
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• 제16권2호
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• pp.83-94
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• 2007

Woven sisal textile fiber reinforced composites were used to evaluate fracture toughness, tensile and three-point bending. The water absorption testing of all specimens was repeated five times in this study. All specimens were immersed in pure water during 9 days at room temperature, and dried in 1 day at $50^{\circ}C$. Two kinds of polymer matrices such as epoxy and vinyl-ester were used. Fractured surfaces were taken to study the failure mechanism and fiber/matrix interfacial adhesion. It is shown that it can be enhanced to improve their mechanical performance to reveal the relationship between fracture toughness and water absorption fatigue according to different polymer matrices. Water uptake of the epoxy composites was found to increase with cycle times. Mechanical properties are dramatically affected by the water absorption cycles. Water-absorbed samples showed poor mechanical properties, such as lower values of maximum strength and extreme elongation. The $K_{IC}$ values demonstrated a decrease in inclination with increasing cyclic times of wetting and drying for the epoxy and vinyl-ester.

• Bulletin of the Korean Chemical Society
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• 제15권10호
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• pp.836-841
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• 1994

The polymer matrix effect on the selectivity, response rate and reproducibility for coextraction type anion-selective optode membranes were investigated with DOA-plasticized PVC, PVC/hydroxylated PVC, PU/hydroxylated PVC and DOS-plasticized CTA matrices. Optode membranes were prepared with TDMACl and ETH2412 dissolved in one of the four solvent polymeric matrices. The PU/hydroxylated PVC and PVC-based membranes have almost the same selectivity coefficients, while the CTA-based membrane is more selective toward lipophilic anions. The membrane with PU/hydroxylated PVC adhered strongly to a glass surface, and showed highly reproducible and relatively rapid response. Very poor adhesion of PVC/hydroxylated PVC and CTA-based membranes limited the usability of those membranes as sensor components. Based on these results, and considering the biocompatibility for clinical samples, the optode made with PU/hydroxylated PVC was applied to determine the thiocyanate ion in human saliva. The results obtained with this simple device were comparable to those with rather complicated ISE methods.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권1호
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• pp.47-59
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• 2015

A bioactive and multifunctional elastin-like polymer (ELP) was produced by genetic engineering techniques to develop new artificial matrices with the ability to mimic the extracellular matrix (ECM). The basic composition of this ELP is a thermo- and pH-sensitive elastin pentapeptide which has been enriched with RGD-containing domains, the RGD loop of fibronectin, for recognition by integrin receptors on their sequence to promote efficient cell attachment. Hydrogels of this RGD-containing polymer were obtained by crosslinking with hexamethylene diisocyanate, a lysine-targeted crosslinker. These materials retain the "smart" nature and temperature-responsive character, and the desired mechanical behavior of the elastin-like polymer family. The influence of the degree of crosslinking on the morphology and properties of the matrices were tested by calorimetric techniques and scanning electron microscopy (SEM). Their mechanical behavior was studied by dynamical mechanical analysis (DMA). These results show the potential of these materials in biomedical applications, especially in the development of smart systems for tissue engineering.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3218-3224
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• 2012

Uniform and well dispersed metal sulfide semiconductor nanoparticles incorporated into matrices of alginate biopolymer are prepared by using a facile in situ method. The reaction was accomplished by impregnation of alginate with divalent metal ions followed by reaction with thioacetamide. XRD analysis showed that the nanoparticles incorporated in the polymer matrix were of cubic structure with the average particle diameter of 1.8 to 4.8 nm. Field emission scanning electron microscopy and high resolution transmission electron microscopy images indicated that the particles were well dispersed and distributed uniformly in the matrices of alginate polymer. FT-IR spectra confirmed the presence of alginate in the nanocomposite. The crystalline nature and thermal stability of the alginate polymer was found to be influenced by the nature of the divalent metal ions used for the synthesis. The proposed method is considered to be a simple and greener approach for large scale synthesis of uniform sized nanoparticles.

• 폴리머
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• 제30권6호
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• pp.538-544
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• 2006

치과용 재료로 사용되고 있는 환경호르몬으로 추정되는 비스페놀 A를 함유한 2,2-bis[4- (2'-hydroxy-3'-methacryloyloxypropoxy)phenyl]propane(Bis-GMA)을 대체할 수 있는 화학적 구조가 Bis-GMA와 유사한 2종류의 신규 2관능성 methacrylated prepolymer인 170-2MA와 631-2MA를 합성하였다. 이렇게 합성된 pre-polymer를 희석제와 다른 단량체를 혼합하여 새로운 치과용 유기 매트릭스를 제조하였으며, 신규 prepolymer치 수율과 점도 및 화학적 구조와 유기 매트릭스의 물리적 및 기계적 물성을 평가하였다. 비스페놀 A를 함유하지 않은 2종류의 에폭시 화합물과 methacrylic acid의 개환반응에 의해서 각각 methacrylation하여 합성된 prepolymer는 90% 이상의 높은 반응 수율을 보였으며 control인 Bis-GMA에 비해서 상대적으로 낮은 점도를 보였다. 또한 합성된 methacrylated prepolymer는 Bis-GMA와 유사한 화학적 구조임을 $^1H-NMR$과 FTIR 분석결과로부터 확인하였다. 2종류의 합성 prepolymer를 이용하여 제조한 유기 매트릭스의 경화시간, 중합 수축률, 광전환율, 중합깊이 및 압축강도는 control인 Bis-GMA를 함유한 것에 비해서 비슷하거나 약간 더 우수한 특성을 나타내었다. 따라서 본 연구에서 합성한 비스페놀 A를 함유하지 않은 170-2MA와 631-2MA prepolymer는 현재 사용중인 Bis-GMA를 대체할 수 있는 새로운 치과용 고분자재료로 충분히 적용이 가능할 것으로 사료된다.

• Macromolecular Research
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• 제15권6호
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• pp.527-532
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• 2007

Polymer hydrogel has attracted considerable interest as a soft material which is finding expanding applications in pharmaceutics and various biomedical fields. In this work, modified PNVP hydrogels were synthesized by crosslinking polymerization of NVP monomer in the presence of PEG macromer with a methoxy end. The effect of the tethered PEG chain on the properties of the hydrogel was investigated in terms of its swelling capacity, compression gel strength, and the morphology of the resulting hydrogels. These PEG-modified PNVP hydrogels possessed good biocompatibility and a decreased protein (fibrinogen) adsorption, thereby indicating their potential as novel drug delivery matrices and scaffold for tissue engineering.