• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.2
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• pp.133-139
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• 2018

Chemically damaged hair is vulnerable to external stimuli in daily life due to the weakened physical properties of the hair strand itself. The purpose of this work was to determine whether chemical conjugation between hair keratin proteins restores tensile strength and thus results inpreventing further deterioration under repeated combing. A model damaged hair tress was produced by a typical perm-process. Then, it was internally crosslinked by the bifunctional crosslinker (3-aminopropyl)triethoxysilane (APTES), via both silane coupling and carbodiimide chemistry. Physical properties, including tensile strength, Young's modulus, and plateau stress, were measured to verify the effect of internal crosslinking, and the existence of crosslinking was verified by Fourier transform infrared (FT-IR) spectroscopy. The degrees of hair breakage and split ends were evaluated by repeated combing-drying tests. Physical properties of chemically damaged hair were restored by internal crosslinking. Successful crosslinking of APTES via both silane coupling and carbodiimide chemistry was verified by FT-IR spectra. Prevention of breakage and split ends after repeated combing with heat was observed. Human hair can be weakened by chemical damage including perm-processing, so restoring such properties is a major issue in the hair care industry. This work shows that internal crosslinking of damaged hair via chemical conjugation would be a potent method to restore the healthy hair.

• Polymer(Korea)
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• v.38 no.6
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• pp.760-766
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• 2014

Bead type super-absorbent resins to be used for release-control were prepared by modification of the inverse suspension polymerization, and their physical properties were characterized. Acrylic acid and acrylamide were used as monomers, and N,N-methylenebisacrylamide was used as crosslinker, controlling the viscosity of monomer solution by adding hydroxyethylcellulose (HEC). SEM studies of the synthesized beads verified that the bead surfaces had many pores with their diameters of several tens nm. The bead sizes were in the range of $500{\sim}3000{\mu}m$, depending on the viscosity of the monomer solution. Both absorbent amount and absorbent rate of the beads were inversely proportional to the bead size, and the maximum water absorbent amount of 1 g beads was determined to be ca. 170~200 g for 5 hrs. The absorbent rate was also dependent on pH change of the aqueous solution, exhibiting the maximum rate in pH ranging from 5 to 11. The absorbent rate decreased as the concentration of salt (NaCl and $MgCl_2$) or ethanol and ethylene glycol increased. Release time of the water absorbed into the bead resins was 700 hrs, confirming the usefulness of the resin for the good release-control materials.

• Membrane Journal
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• v.16 no.4
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• pp.241-251
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• 2006

In this study, crosslinked copolyimides with random (r-) and block (b-) structure were fabricated using N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid and pentanediol as crosslinkers. Linear r- and b-sulfonated copolyimides were also fabricated for comparison. Ion exchange capacities of r- and b-copolyimides were very similar to each other owing to their strong dependence of sulfonic acid content. The physical crosslinking via dimerization of carboxylic acid groups induced a reduced average interchain distance in b-copolyimide without crosslinkers. Consequently, its water uptake and methanol permeability were lower than those of r-sulfonated copolyimides. Simultaneously, the reduced interchain distance increased the content of fixed-charged ions per unit volume. The high fixed-charged ion density contributed to an enhancement of proton conductivity In the b-sulfonated copolyimide. Crosslinking caused the reduction of average interchain distance between polymer chains irrespective of types of crosslinker and polymer structure, leading to low methanol permeability. On the contrary, their proton conductivity was improved owing to formation of effective hydrophilic channels responsible for proton conduction. In particular, this trend was observed in r-copolyimide containing a fixed charged ion.

• Applied Chemistry for Engineering
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• v.27 no.2
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• pp.221-226
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• 2016

Production of eco-friendly and biologically harmless materials is strongly required in all industries. In particular, reducing volatile organic compounds in coating processes is extremely important to secure worker's safety. During recent two decades, extensive research works on water-borne polyurethane dispersion (PUD) have been continuously developed as an alternative to solvent-borne polyurethane. However, PUD was shown inferior mechanical properties to the organic solvent-borne polyurethane due to a limit to the molecular weight increase, which resulted in the limit of applications. To overcome this drawback, several approaches have been examined such as polymer blends and thermal/radiation induced crosslinking. Among these methods, the radiation curing system was suitable for industrialization because of the high crosslinking density and fast curing speed. In this study, we overcame the drawback for PUD via introducing benzophenone radiation curable units to PUD. We synthesized PUD films which possessed good dispersion in water for 30 days, increased Tg and Td more than $5^{\circ}C$ after UV curing film as well as improved young's modulus more than double.

• Membrane Journal
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• v.31 no.3
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• pp.219-227
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• 2021

Molecularly imprinted membrane (MIM) is a porous polymer membrane incorporating with the molecular recognizing sites. In this study, the supporting P(AN-co-MA) asymmetric membrane was prepared by nonsolvent induced phase separation (NIPS) method. And then, MIM with lysozyme template sites was prepared using the surface imprinting method on the P(AN-co-MA) asymmetric membrane introducing a photoactive iniferter and then photo-grafting. The P(AN-co-MA) asymmetric membrane was modified with 3-chloropropyltrimethoxysilane and dithiocarbamate as a photoactive iniferter. To prepare a lysozyme imprinted membrane, the modified P(AN-co-MA) membrane was copolymerized with acrylamide as a functional momomer, N,N'-methylene bisacrylamide as a crosslinker and lysozyme as a template in the UV irradiation environment. The lysozyme imprinted MIM was analyzed by using SEM, FT-IR and EDS measurements. Its results confirm that all the P(AN-co-MA) membranes have an asymmetric structure and the iniferter group is successfully introduced on the membrane surface. The process parameters were adjusted to obtain MIM having the excellent lysozyme adsorption. The maximum lysozyme adsorption capacity reaches at 2.7 mg/g, which is 13 times higher than that of the non imprinted membrane (NIM). The permselective membrane filtration experiments of ovalbumin to lysozyme show that the P(AN-co-MA) MIM preferentially bounds a greater amount of lysozyme.

• Journal of the Korean Society of Radiology
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• v.16 no.2
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• pp.103-113
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• 2022

In this paper, a combined ¹⁸F-FDG(fluorodeoxyglucose) and MNP(magnetic nanoparticles) contrast agent was synthesized using N-(p-maleimidophenyl) isocyanate as the crosslinker for use in simultaneous PET-MRI scans. PET-MRI images were acquired and evaluated before and after injection of the combined contrast imaging agent (¹⁸F-FDG labeled MNP) from a glioma stem cell mouse model. After setting the region of interest (ROI) on each acquired image, the area of the lesion was calculated by segmentation. As a result, the PET image was larger than the MRI. In particular, the simultaneous PET-MRI images showed accurate lesions along with the surrounding soft tissue. The mean and standard deviation values were higher in the MRI images alone than in the PET images or the simultaneous PET-MRI images, regardless of whether the contrast agent was injected. In addition, the simultaneous PET-MRI image values were higher than for the PET images. For PSNR experiments, the original image was PET Image using 18F-FDG, MRI using MNPs, and MRI without contrast medium, and the target image was simultaneous PET-MRI image using 18F-FDG labeled MNPs contrast medium. As a result, all of them appeared significantly, suggesting that the 18F-FDG labeled MNPs contrast medium is useful. Future research is needed to develop an agent that can simultaneously diagnose and treat through SPECT-MRI imaging research that can use various nuclides.