• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.481-489
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• 1996

D,L-lactide (2-LA) was copolymerized with ${\beta}$-methyl-${\delta}$-valerolactone (MVL) using tetraphenyltin as a catalyst and the properties of the copolymers were investigated. The composition of the repeating unit of lactic acid in the copolymers was higher than that in the monomer feeds. The composition of the lactic acid unit in the copolymers decreased with increasing copolymerization time. The yield and the molecular weight of the copolymer increased with increasing 2-LA in the feed composition. These results suggest that the reactivity of 2-LA is larger than that of MVL. The number average molecular weight was in the range of 54,000 to 63,000 and the polydispersity index was in the range of 1.7 to 2.1. The copolymers did not show melting point, but glass transition temperature. The degradable tendency of the copolymers with lipase was almost equal to that of L-lactide-MVL copolymer.

• Polymer(Korea)
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• v.26 no.1
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• pp.9-17
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• 2002

The free radical bulk copolymerizations of perfluoroalkylethyl acrylate(FA) containing perfluoro group ($CF_3(CF_2)_nCH_2CH_2$-; n=5, 7, 9, 11) with styrene were conducted at $60^{\circ}C$ using AIBN as an initiator. Reactivity ratios($r_1$, $r_2$) were determined from monomer feed compositions and the NMR spectroscopically measured copolymer compositions using Kelen-Tudos method. The structures of copolymers were characterized with FT-IR and $^1H-NMR$ analysis. Their thermal properties investigated with DSC and TGA were decreased with increasing the content of fluorinated acrylate in the copolymer. Their surface free energies were calculated with measuring contact angles of the copolymers and PMMA blends with a small amount of them.

• Polymer(Korea)
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• v.28 no.1
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• pp.86-91
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• 2004

Hydrogels with enhanced biocompatibility and biostability were prepared by copolymerization of 2-hydroxyethyl methacrylate (HEMA) and sodium methacrylate (SMA) at high monomer concentration to replace a sponge which has limited applications as an implant material. It was found that incorporation of SMA moiety suppressed cytotoxicity. P(HEMA-co-SMA) hydrogel prepared at SMA feed ratio of 0.05 showed minimal cytotoxicity as compared with a normal cell culture plate. The adhesion and the spreading of cells were preferred on the surface of the hydrogel prepared with SMA feed ratio of 0.01. On the other hand, the hydrogel prepared with SMA feed ratio of 0.05 showed lower cell adhesion. Histological findings revealed no evidence of significant foreign body reaction in the tissues around the copolymer hydrogels. Conclusively, it is suggested that the hydrogels prepared by copolymerization of HEMA and SMA at high monomer concentration are strong candidates for an implant material with excellent biocompatibility and biostability.

• Polymer(Korea)
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• v.36 no.3
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• pp.302-308
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• 2012

The objective of this study is to investigate optimum reaction conditions for the grafting of poly($N$-vinyl- 2-pyrrolidone) (PVP) onto the surface of plasma-treated polypropylene film. The plasma treatment conditions were fixed as 200 W rf power, 6 LPM Ar flow rate, 30 sec treatment time, and 5 min exposure time after treatment. For graft copolymerization, we investigated the change of grafting degree with respect to reaction time, reaction temperature and $N$-vinyl-2-pyrrolidone concentration. Maximum grafting degree was obtained at the conditions of 6 h reaction time, $90^{\circ}C$ reaction temperature, and 40% $N$-vinyl-2-pyrrolidone concentration. The introduction of PVP was confirmed by ATR-FTIR, XPS, and SEM analysis.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.137-141
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• 2008

Copolymerization of ethylene and ${\alpha}$-olefin using $rac-Et[Ind]_2ZrCl_2/MAO$ catalyst embedded onto polysty-rene was examined. The embedded catalyst was prepared by polymerizing a small amount of styrene with $rac-Et[Ind]_2ZrCl_2$. The catalytic activities of the embedded catalyst were higher than those of the homogeneous catalystregardless of comonomer type and the characteristic of the active sites of the embedded catalyst was not affected duringthe embedding process. Based on the DSC and NMR analyses of the produced copolymers, it was thought that theembedded catalyst had similar or slightly better comonomer incorporation ability. Furthermore, the copolymers produced by the embedded catalyst had higher bulk densities and better particle morphology than those by the homogeneous catalyst.

• Membrane Journal
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• v.17 no.4
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• pp.294-301
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• 2007

To improve oxidative stability of non-fluorinated styrene-based polymer electrolyte membranes, copolymerized membranes were prepared using styrene derivatives such as p-methylstyrene, t-butylstyrene, and ${\alpha}-methylstyrene$ by monomer sorption method. Prepared membrane was characterized by measurement of weight gain ratio, water content, ion-exchange capacity, proton conductivity, and oxidative stability under the accelerated condition. It was found that each step of monomer sorption method including sorption, polymerization and sulfonation could be affected by the properties and the structures of styrenederivatives. Due to difficulty of polymerization, ${\alpha}$-methylstyrene was copolymerized with styrene or p-methylstyrene. Prepared membrane using ${\alpha}-methylstyrene$ and styrene showed higher performance and stability comparing to copolymerized membrane with styrene. However, copolymerized membranes with ${\alpha}-methylstyrene$ did not showed much improved oxidative stability comparing to styrene membrane due to their lower molecular weight. The t-butylstyrene membrane showed a low performance due to substituted bulky-butyl group which prevents sorption and sulfonation reaction. However, copolymerized t-butylstyrene membranes with p-methylstyrene showed good performance and much improved stability than the styrene membranes.

• Polymer(Korea)
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• v.27 no.5
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• pp.429-435
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• 2003

Vinyl addition copolymerizations of norbornene (NB) and 5-vinyl-2-norbomene (VNB) were carried out using a cationic η$^3$-allyl palladium catalyst in the various mole ratio of comonomers. The copolymers could be obtained in good yield (65∼85%) with high weight-average molecular weights (M$_{w}$ > 760,000). Depending on increasing VNB contents, the molecular weight and yield of the copolymers decreased. FT-IR analysis confirmed that actual contents of VNB in polymer were proportional to the feeding content of VNB. From $^1$H-NMR spectroscopy, we found that both exo and endo VNB isomer were copolymerized with NB. Thermal stabilities of NB-VNB copolymers were independent on the VNB content and their initial decomposition temperatures were about 300 C. The NB-VNB copolymers were followed by epoxidation by using m-CPBA and hydroxylation by 9-BBN, respectively, and these post-polymers were characterized by FT-IR spectroscopy and $^1$H-NMR analysis..

• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.80-84
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• 1998

Poly(ethylene terephthalate)(PET)는 물리적, 기계적 성질이 우수한 고결정성 고분자의 하나로 섬유, 필름 및 여러 가지 용도로 다양하게 사용되고 있으나, 일반적으로 흡습성, 난연성 및 염색성 등이 좋지 않은 결점이 있다. 따라서 이러한 결점을 개선하기 위하여 PET 자체의 성질을 개선하거나 다른 고분자와의 공중합 또는 블렌딩하는 방법, 첨가제의 도입, 그래프팅 등 PET의 개질 연구가 많이 수행되고 있으나 대표적인 방법으로 합성반응시 공단량체를 사용하여 공중합체를 제조하는 것이 널리 알려져 있다.(중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.221-226
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• 2008

Novel synthetic routes were proposed for hydroxy-terminated Poly(EO-co-THF) by Cationic ring-opening copolymerization of Tetrahydrofuran(THF) and Ethylene oxide(EO). It was carried out using Boron trfluoride tetrahydrofuranate($BF_3$ THF complex) as catalyst in the presence of 1,4-butandiol. The resultant products are well-defined linear polyetherpolyol. Polyurethane(TPU) were prepared using resultant polyetherpolyol with IPDI/N-100 as curing agent and TPB(Triphenylbismuth) /MA(Maleic anhydride) mixture as cure catalyst. Mechanical properties of TPU prepared from poly(EO-co-THF) polyol were investigated and compared with polyurethane using ATK HTPE.

• Polymer(Korea)
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• v.24 no.6
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• pp.751-756
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• 2000

The copolymerization of ethylene (E) and cycloolefin (CO) was carried out with rac-Et(Ind)$_2$ZrC $l_2$ and MMAO cocatalyst system to examine the effect of CO structure on catalytic behaviors and properties of copolymer (COC). Various cycloolefins such as norbornene (N), 5-phenyl-2-norbornene (PN) and 5-vinyl-2-norbornene (VN) were used as comonomers. With increasing [CO]/[E] feed ratio, the catalytic activity decreased while the glass transition temperature of copolymer increased. With analysis of the structure of E/VN copolymer by FT-IR and $^{l3}$C-NMR, it was found that the cyclic C=C bond of VN comonomer is selectively polymerized and the vinyl C=C bond remains unreacted. The resulting vinyl C=C bond attached into copolymer provided the functionalization moiety using glycidyl methacrylate.e.