• Proceedings of the Korean Fiber Society Conference
• /
• 2002.04a
• /
• pp.351-351
• /
• 2002

새로운 LCST 형 블록 공중합체를 설계하기 위하여 LCST 블렌드 계를 선정하고, 이로부터 대응되는 블록 공중합체를 고안하였다 고안된 블록 공중합체의 분자 변수와 자기 집합에 의한 나노 미세 상 발현 거동과의 관계를 Cho의 압축성 random-phase approximation (RPA) 이론을 이용하여 구하였다. 본 연구의 대상 물질은 polystyrene (PS)과 poly(vinyl methyl ether) (PVME), PS 와 Poly(cyclo hexyl methacrylate) (PCHMA)의 블록 공중합체이다. (중략)

• Macromolecular Research
• /
• v.11 no.5
• /
• pp.303-310
• /
• 2003

The phase behavior of binary blends of dimethylpolycarbonate-tetramethyl polycarbonate (DMPCTMPC) copolycarbonates and styrene-acrylonitrile (SAN) copolymers has been examined and then compared with that of DMPC/TMPC/SAN ternary blends having the same chemical components and compositions except that the DMPC and TMPC were present in the form of homopolymers. Both binary and ternary blends were miscible at certain blends compositions, and the miscible blends showed the LCST-type phase behavior or did not phase separated until thermal degradation temperature. The miscible region of binary blends is wider than that of the corresponding ternary blends. Furthermore, the phase-separation temperatures of miscible binary blends are higher than those of miscible ternary blends at the same chemical compositions. To explain the destabilization of polymer mixture with the increase of the number of component, interaction energies of binary pairs involved in these blends were calculated from the phase separation temperatures using lattice-fluid theory and then the phase stability conditions for the polymer mixture was analyzed with volume fluctuation thermodynamics.

• Macromolecular Research
• /
• v.10 no.2
• /
• pp.91-96
• /
• 2002

To explore the effects of intramolecular interactions within the copolymer on the phase separation behavior of polymer blends, copolymers having two different types of intramolecular interactions, i.e., intramolecular repulsion and intramolecular attraction were prepared . In this study, poly(styrene-co-methylmethacrylate) (P(S-MMA)) having intramolecular repulsion caused by positive interaction between styrene and MMA and poly(styrene-co-ethyl-methacrylate) (P(S-EMA)) and poly(styrene-co-cyclohexylmethacrylate) (P(S-CHMA)) having intramolecular attraction caused by negative interaction between styrene and methacrylate were blended with tetramethyl poly-carbonate (TMPC). The phase behavior of blends was examined as a function of copolymer composition and blend composition. TMPC formed miscible blends with styrenic copolymers containing less than certain amount of methacrylate. The phase separation temperature of TMPC blends with copolymer such as P(S-MMA) and P(S-EMA), first increases with methacrylate content, goes through a maximum and then decreases just prior to the limiting content of methacrylate for miscibility, while that of TMPC blends with P(S-CHMA) always decreases. The calculated interaction energy for TMPC-P(S-EMA) pair is negative and monotonically increases with EMA content of the copolymer. Such behavior contradicted the general notion that systems with more favorable energetic interactions have higher LCST, The detailed inspection of the lattice-fluid theory related to the phase behavior was performed to explain such behavior.

• Elastomers and Composites
• /
• v.39 no.4
• /
• pp.318-323
• /
• 2004

Cloud-point and bubble-point curves for poly(ethylene-co-13.8 mol% octene) ($PEO_{13.8}$) and Poly(ethylene-co-15.3 mol% octene) ($PEO_{15.3}$) were determined up to $150^{\circ}C$ and 450 bar in hydrocarbons which have different molecular size and structure. Whereas ($PEO_{15.3}$+ n-pentane) system has cloud-point and bubble-point type transitions, ($PEO_{15.3}$+ n-propane) and ($PEO_{15.3}$+ n-butane) systems do only cloud-point type transition. In cyclo-pentane, -hexane, -heptane, and -octane, $PEO_{15.3}$ has a bubble-point transition. ($PEO_{13.8}$+ n-butane) mixture has a critical mixture concentration at 5 wt% PEO. (PEO + hydrocarbon) mixtures exhibit LCST type behavior. Solubility of PEO increases with hydrocarbon size due to increasing dispersion interaction which is favorable to dissolve PEO.

• Elastomers and Composites
• /
• v.38 no.1
• /
• pp.51-56
• /
• 2003

Cloud-point and bubble-point data to $170^{\circ}C$ and 50 bar are presented for four different solvents, normal pentane. n-hexane, n-heptane, and n-octane with poly(ethylene-co-42 wt% octene) ($PEO_{42}$) copolymer. The pressure-concentration isotherms measured for $PEO_{42}$ - normal pentane have maximums at around 5 wt% of the copolymer concentrations in the solution. $PEO_{42}$- normal pentane system exhibits LCST-type phase behavior at temperatures greater than $130^{\circ}C$. Below $120^{\circ}C$, bubble-point type transitions are observed. However, the binary mixtures for $PEO_{42}$ in n-hexane, n-heptane, and n-octane have only bubble-point type transitions at the pressure-temperature region investigated in this study. The single-phase region of PEO - alkane mixtures increases with the molecular size of alkane solvent due to the increasing dispersion interactions between PEO and the alkane.

• Polymer(Korea)
• /
• v.24 no.5
• /
• pp.682-689
• /
• 2000

The information related to the interaction energy between repeat units is essential for the production of useful polymer blends via molecular structure design. Based on the interaction energies obtained here, a method for the fabrication of miscible blend was suggested. An investigation related to the equilibrium phase behavior of polymer blends of various polycarbonates with various polymethacrylates was performed and then based on the obtained interaction information miscible polymer blends were produced by controling molecular structure of polymer. Binary interaction energies between repeat units were calculated from the lower critical solution temperature-type phase boundary using an equation of state combined with binary interaction model.

• Polymer(Korea)
• /
• v.26 no.2
• /
• pp.245-252
• /
• 2002

Thermodynamics and gas transport properties of polymethylmethacrylate (PMMA) blends with polyvinylmethylether (PVME) containing various amount of poly (styrene-b-methylmethacrylate) copolymer (P(S-b-MMA)) as a compatibilizer were studied. To extract interaction energies of binary pairs involved in the blends from the phase separation temperatures using an equation-of-state theory, PVME blends with methylmethacrylate copolymers containing various amount of styrene (SMMA) were prepared. PVME formed miscible blends with methylmethacrylate copolymers containing more than 70 wt% styrene and these miscible blonds showed a LCST-type phase separation behavior. Based on the interaction information obtained here, P(S-b-MMA) copolymer was added to the PMMA/PVME blends to enhance their compatibility. The average diameter of the dispersed rubber particles was gradually decreased for the blends of containing P(S-b-MMA) from 0 to 5 phr and then leveled off at a fixed size. At a fixed bland composition, the gas permeation was also increased as the P(S-b-MMA) content increased from 0 to 5 phr and then leveled off when the P(S-b-MMA) content was higher than 5 phr.

• Textile Coloration and Finishing
• /
• v.22 no.3
• /
• pp.181-186
• /
• 2010

A thermoresponsive poly(NIPAM-co-dye) labeled with benzopyran-based D-$\pi$-A type dye was prepared by typical radical copolymerization. It can be also constructed a acid/base-induced molecular switch by modulation of intramolecular charge transfer with protonation/deprotonation. The lower critical solution temperature behavior was investigated by means of UV-vis spectroscopy which allows the measurement of the phase transition from $25^{\circ}C$ to $45^{\circ}C$ in aqueous DMSO solution. The morphology of the internal microstructure of the poly(NIPAM-co-dye) hydrogel was observed by scanning electron microscopy. The reversible switch could be obtained by thermal and acid/base stimuli.