• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.17-25
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• 2014

Wide spread application and non-biodegradability of the poly(ethylene terephthalate) generate a huge amount of waste and disposal, posing serious environmental problems. Disposal of the PET wastes also can be thought as an economic loss of valuable chemical resources. We present various ways of feedstock recycling of PET waste to deal with environmental and economic problems. Feedstock recycling is one of promising technologies. It is based on the concept of depolymerizing the condensation polymer such as PET through solvolytic chain cleavage into low molecular products which can be purified and reused as raw materials for the production of high quality chemical products.

• Polymer(Korea)
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• v.38 no.3
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• pp.386-390
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• 2014

Efficient stitching methods for the synthesis of tripodal Fr$\acute{e}$chet-type dendrimers containing secondary amine as a connector were elaborated. The synthetic strategy involved Staudinger/aza-Wittig reactions (new click reaction) between tripodal tris(azides) and aldehyde-dendrons in toluene in the presence of triphenylphosphine and followed by the reduction of imine intermediates. The tripodal core (1,3,5-tris-(3-azido-propoxy)-benzene) was chosen to serve as the azide functionalities for dendrimer growth. 1,3,5-Tris-(3-azido-propoxy)-benzene was stitched with the aldehyde-functionalized Fr$\acute{e}$chet-type dendrons via Staudinger/aza-Wittig reactions leading to the formation of the corresponding Fr$\acute{e}$chet-type dendrimers in high yields.

• Polymer(Korea)
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• v.29 no.1
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• pp.74-80
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• 2005

To use the filter materials for reduction of carbonyl compounds in cigarette mainstream smoke, the bead type cation and anion exchangers were synthesized by the suspension polymerization of GMA and DVB followed by the subsequent functionalization with sodium sulfite and diethylamine, respectively. FT-IR/ATR was used to characterize functionalized copolymer formation by sulfonation and amination, and the morphology change of ion exchangers according to the adsorption of cigarette mainstream smoke were observed by SEM. Ion exchange capacity, functionalization yield and adsorption properties of carbonyl compounds in cigarette mainstream smoke were investigated. The highest functionalization yields and ion exchange capacity were obtained at 5 wt% DVB content in co-monomer. The adsorption amount of carbonyl compounds in cigarette mainstream smoke of anion exchanger was higher than that of cation exchanger because of its electron delocalization in carbonyl group. The adsorption efficiency was increased in the presence of moisture. This results indicated that the anion exchanger was applicable for cigarette filter material because of its large ion exchange capacity and rapid ion exchange reaction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2544-2549
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• 2013

In prepaparation of the high performance polymer/clay nanocomposite, it is essential to modify the hydrophillic $Na^+$-MMT to hydrophobic alkyl ammonium-MMT via organic surfactant. The organic surfactant, VDAC (vinylbenzyldimethyl-dodecylammonium chloride) was synthesized from two primary chemicals and $VDA^+$-MMT was prepared from $Na^+$-MMT through a cation exchange reaction between $Na^+$ and $VDA^+$ (vinylbenzyldimethyl-$dodecylammonium^+$) cation. $VDA^+$-MMT was then dispersed in styrene and polystyrene/$VDA^+$-MMT nanocomposite was fabricated by in-situ polymerization reaction. The clay dispersion and barrier property of the nanocomposite were investigated. From the investigations, it was confirmed that dispersion of the $VDA^+$-MMT was enhanced compared with that of $Na^+$-MMT and as a consequency of better dispersion, barrier property of organic solvent was improved in a great extent.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.317-322
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• 2012

The microstructures were examined by SEM, FT-IR spectra, tensible properties mole % of [NCO/OH], and particle size analyzer. Growing concerns in the environment-friendly industries have led to the development of solvent-free formulations that can be cured. We had synthesized the polyurethane resin having the ability to protect stainless steel against corrosion. Compared with general packing materials and coatings, this resin is highly stronger in intensity and longer durability. Polyurethane resins were composed of polyols, IPDI, silicone surfactant, catalyst and crosslink agent. Moreover, thermal fillers such as $Al_2O_3$, fume silica and $ZrO_2$ not only accelerated the curing rate but also improved the physical property as thermal barriers. The rigid segments of polyurethane in mechanical properties were due to crosslink agent and the increase of [NCO/OH]. In conclusion, the polyurethane microstructure with crosslink agent can be good material for themoset coating of metal substrates such as stainless steel.

• Polymer(Korea)
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• v.30 no.6
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• pp.538-544
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• 2006

Two kinds of novel bifunctional methacrylated prepolymers (170-2MA and 631-2MA) which have similar structure with 2,2-bis[4- (2'-hynroxy-3'-methacryloyloxypropoxy)phenyl] propane (Bis-GMA) was synthesized for dental applications as an alternative to Bis-GMA containing bisphenol A that is doubtful as an endocrine disrupter. The organic matrices were prepared by mixing a diluent and/or a monomer with the synthesized methacrylated prepolymers. The yield, viscosity, and chemical structures of the prepolymers and the physical and methanical properties of the organic matrices were evaluated. The yields of the prepolymers synthesized through a ring-opening reaction of epoxy compound and methacrylic acid were above 90% and the viscosities of the prepolymers were much lower than that of the Bis-GMA control. From the results of $^1H-NMR$ and FTIR analyses, the chemical structures of the prepolymers were similar to that of Bis-GMA. In addition, the curing time, poly-merization shrinkage, photoconversion, polymerization depth, and compressive strength of the organic matrices formulated with 170-2MA and 631-2MA prepolymers exhibited comparable to or better than those of the existing Bis-GMA-based one. These results suggest that the novel methacrylated prepolymers which have no endocrine disrupter can be an alternative to Bis-GMA and be applicable to dental polymer materials.

• Polymer(Korea)
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• v.36 no.4
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• pp.427-433
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• 2012

A series of poly(imide-aramid-sulfone)s with alternatingly introduced imide/aramid groups were prepared by reacting divinyl sulfone (DVS) and $N^1,N^4$-bis(4-(vinylsulfonyl)phenyl)terephthalamide (2) with pyromellitic diimide. Three model compounds, N-[2-(p-aminophnenylsulfonyl)ethyl]phthalimide (3), 2,2'-(2,2'-sulfonylbis(ethane-2,1-diyl))diisoindoline-1,3-dione (4), and N,N-bis(4-(2-(1,3-dioxoisoindolin-2-yl)ethylsulfonyl)phenyl)terephthalamide (5), resembling polymers were prepared with good yields by reacting p-aminophenyl vinyl sulfone, DVS, and 2 with phthalimide. Condensation polymerization was carried out by Michael-type addition reaction of the difunctional phthalimide group with the DVS group in the presence of tetrabutylammonium hydroxide (TBAH), resulting in poly(imide-aramid-sulfone)s 6-12 with moderate molecular weights and good yields. They were highly soluble in polar solvents such as N,N-dimethylformamide, dimethylsulfoxide, N-methylpyrrolidinone and tetrahydrofuran. The ratios of DVS/2 were 1/0, 3/1, 2/1, 1/1, 1/2, 1/3, and 0/1. Molecular weight and physical properties such as solubility, viscosity, and thermal properties of the polymers were examined.

• Polymer(Korea)
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• v.29 no.5
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• pp.433-439
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• 2005

The copolymers were prepared by the emulsion copolymerization of fluoroalky lacrylate-stearylacrylate-m-isopropenyl-${\alpha},\;{\alpha}'$-dimethylbenzyl isocyanate (TMI) in order to obtain water repellent polymers. The respective copolymerization rates of the three monomers considerably depended upon the use of the nonionic emulsifier and the nonionic-cationic mixed emusifier, and the optimum conditions were obtained. The particle sizes of the copolymers were in the range of 105 to 222nm. The particle sizes of the copolymers prepared by the use of the mixed emulsifiers were smaller than those of the copolymers prepared by the use of the nonionic emulsifier. The reactions of both TMI-N-methyl acetamide and TMI-cellobiose did not take place. However, the reaction of TMI-n-butylamine occurred. The water contact angles before and after washing three times for nylon and poly(ethylene terephthalate) (PET) fabrics coated with the copolymer prepared by the use of mixed emulsifier were about $139^{\circ}\;and\;133^{\circ}$ Therefore, the copolymer showed good durable repellency for nylon and PET.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.871-877
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• 1994

Most of the aromatic nitro compounds were reduced to amines in high yield by transfer of hydrogen from 4-vinyl cyclohexene to the substrate via palladium catalyst. The usefulness of the method is not affected by the presence of a variety of other functional groups such as -OH, $-OCH_3$, $-CH_3$, $-CO_2H$, and -Cl, except for halogen which is removed during hydrogenation. The reduction of ortho-substituted nitrobenzene such as o-nitrotoluene, o-nitrophenol, o-nitroanisole was slower than the para isomer. Typically, the nitro compound is refluxed in ethanol with a large exess of 4-vinylcyclohexene in the presence of Pd-C catalyst. Under the above conditions, p-nitrobenzaldehyde, p-nitrobenzyl alcohol, and p-nitrobenzyl acetate were reduced to p-toluidine.

• Polymer(Korea)
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• v.31 no.6
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• pp.497-504
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• 2007

We have prepared the dinuclear half-sandwich CGC(constrained geometry catalyst) with polymethylene bridge $[Zr(({\eta}^5\;:\;{\eta}^1-C_9H_5SiMe_2NCMe_3)Me_2)_2\;[(CH_2)_n]$ [n=6(4), 9(5), 12(6)] by treating 2 equivalents of MeLi with the corresponding dichlorides compounds. To study the catalytic behavior of the dinuclear catalysts we conducted copolymerization of ethylene and 1-hexene in the presence of three kinds of boron cocatalysts, $Ph_3C^+[B(C_6F_5)_4]^-\;(B_1),\;B(C_6F_5)_3\;(B_3)$, and $Ph_3C^+[(C_6F_5)_3B-C_6F_4-B(C_6F_5)_3]^{2-}\;(B_2)$. It turned out that all active species formed by the combination of three dinuclear CGCs with three cocatalyst were very efficient catalysts for the polymerization of olefins. The activities increase as the bridge length of the dinuclear CGCs increases. At the same time the dinuclear cocatalyst exhibited the lowest activity among three cocatalysts. The prime observation is that the dinuclear cocatalyst gave rise to the formation of the copolymers with the least branches on the polyethylene backbone.