Kuk Young Cho

Effect of P(lLa-co-εCL) on the compatibility and crystallization behavior of PCL/PLLA blends

This article describes the compatibility of two semicrystalline polymers, poly(e-caprolactone) (PCL) and poly(l-lactic acid) (PLLA). The compatibility of the PCL/PLLA blends was enhanced by the compatibilizing effect of the poly(l,l-lactide-co-e-caprolactone) [P(lLA-co-eCL)]. A discussion details the effect of the concentration of the compatibilizing agent, the copolymer of l,l-lactide and e-caprolactone of a 50/50 mol ratio [P(lLA-co-eCL)], on the compatibility and the crystallization behavior of the blends of PCL and PLLA. It was found that the addition of P(lLA-co-eCL) could suppress the crystallization of PLLA at its Tc and induced the concurrent crystallization of PLLA and PCL.

Grafting of glycidyl methacrylate onto polycaprolactone: preparation and characterization

Abstract Polycaprolactone-graft-glycidyl methacrylate (PCL-g-GMA) copolymer was prepared by grafting GMA onto PCL in a batch mixer using benzoyl peroxide as an initiator. The graft content was determined with the 1H-NMR spectroscopy by calculating the relative area of the characteristic peaks of PCL and GMA. The graft content increased with the increase of GMA concentration. The methine proton peak appearing at 3.65xa0ppm in 1H-NMR spectra could be assigned as a grafting site of GMA by the correlation spectra (H,H-COSY). Molecular weight determination was also carried out for the pure and grafted polymers using gel permeation chromatography to determine chain scission reaction. The detailed grafting reaction mechanism was discussed based on the results of GPC and NMR measurements.

Effects of Triacetoxyvinylsilane as SEI Layer Additive on Electrochemical Performance of Lithium Metal Secondary Battery

The effects of a solid electrolyte interface (SEI) additive, triacetoxyvinylsilane (VS), on the electrochemical performance of a lithium metal secondary battery were investigated. When 2 wt % VS was added to the electrolyte, no lithium dendrite on the lithium metal surface after precycling was observed and thereby the lowest interfacial resistance of the unit cell (LiCoO 2 /Li) could be achieved. With these reasons, the capacity of the unit cell based on the electrolyte containing 2 wt % VS could maintain about 80% of the initial capacity after 200 cycles at a high charge/discharge current density (C/2, 1.25 mA cm -2 ).

Protein release microparticles based on the blend of poly(D,L-lactic-co-glycolic acid) and oligo-ethylene glycol grafted poly(L-lactide).

Bovine serum albumin (BSA), a model protein drug, was encapsulated with a microparticle based on the blend of poly(D,L-lactic-co-glycolic acid) (PLGA) and poly(L-lactide)-g-oligo(ethylene glycol) (PLLA-g-oligoEG). Effects of PLLA-g-oligoEG in the blend on degradation, characteristic properties, and release behavior of the microparticle were studied. Drug loading efficiency increased with increase in the graft frequency of oligoEG in the graft copolymer in the blend. The release of BSA was found to be more efficient for microparticles based on the blend than on the PLGA, which is due to the faster protein diffusion through the swollen phase of the hydrogel-like structure. The microparticles based on the blend showed a slower degradation and a lower pH shift compared to that of PLGA.

Synthesis and characterization of poly(ethylene glycol) grafted poly(L-lactide)

Poly(ethylene glycol) grafted poly(L-lactide) was prepared by ring opening polymerization of L-lactide and epoxy-terminated poly(ethylene glycol) methyl ether (PEGME). Stannous octoate and Al(Et)3·0.5 H2O were tested as polymerization catalysts, and Al(Et)3·0.5 H2O was found to be more effective for the ring-opening of the epoxy group of the modified PEGME monomer. The synthesized polymers were characterized by NMR and the efficiency of the incorporation of epoxy-terminated PEGME in the copolymer was determined.