• Macromolecular Research
• /
• 제15권6호
• /
• pp.553-559
• /
• 2007

Nanocomposite films were prepared by sol-gel synthesis from vanadium triisopropoxide with $poly((oxyethylene)_9$ methacrylate)-graft-poly(dimethyl siloxane), POEM-g-PDMS, producing in situ growth of vanadium oxide within the continuous ion-conducting POEM domains of micro phase-separated graft copolymer. The formation of vanadium oxide was confirmed by wide angle x-ray scattering (WAXS) and Fourier transform infrared (FT-IR) spectroscopy. Small angle x-ray scattering (SAXS) revealed the spatially-selective incorporation of vanadium oxide in the POEM domains. Upon the incorporation of vanadium oxide, the domain periodicity of the graft copolymer monotonously increased from 17.2 to 21.0 nm at a vanadium content 14 v%, above which it remained almost invariant. The selective interaction of vanadium oxide with POEM was further verified by differential scanning calorimetry (DSC) and FT-IR spectroscopy. The nanocomposite films exhibited excellent mechanical properties $(l0^{-5}-10^{-7}dyne/cm^2)$, mostly due to the confinement of vanadium oxide in the POEM chains as well as the interfaces created by the microphase separation of the graft copolymer.

• Macromolecular Research
• /
• 제16권7호
• /
• pp.609-613
• /
• 2008

Poly($\varepsilon$-caprolactone)-poly(ethylene glycol)-poly($\varepsilon$-caprolactone) (PCL-PEG-PCL) multiblock copolymers at various hydrophobic-hydrophilic ratios were successfully synthesized by the chain extension of triblock copolymers through isocyanate (hexamethylene diisocyanate). Biodegradable films were prepared from the resulting multiblock copolymers using the casting method. The mechanical properties of the films were improved by chain extension of the triblock copolymers, whereas the films prepared by the triblock copolymers were weak and brittle. Atomic force microscopy (AFM) of the multiblock copolymer film showed that the hydrophilic PEG had segregated on the film surface. This is consistent with the observed contact angle of the films.

• Korean Chemical Engineering Research
• /
• 제46권1호
• /
• pp.15-22
• /
• 2008

최근 메탈로센 촉매를 통한 올레핀 합성 기술의 발달로 폴리올레핀 블록공중합체를 제조할 수 있는 기술이 개발되었으며 향후 고분자 산업에 크게 기여할 것으로 기대되고 있다. 하지만 현재까지 폴리올레핀 블록공중합체의 특성에 대한 체계적인 연구가 보고되고 있지 못한 실정이다. 본 리뷰 논문에서는 결정질의 poly(ethylene) (E) 블록과 고무질(rubbery)의 블록을 가지는 선형 폴리올레핀 블록공중합체를 통하여 폴리올레핀 블록공중합체의 열가소성 탄성체로서의 열역학적, 기계적 특성 및 분자 구조의 효과 특성 등에 관하여 살펴보고자 한다.

• 한국고분자학회지:고분자과학과기술
• /
• 제16권6호
• /
• pp.754-768
• /
• 2005

• 폴리머
• /
• 제30권2호
• /
• pp.152-157
• /
• 2006

수산기말단 폴리부타디엔(hydroxy-terminated polybutadiene: HTPB) 폴리올을 이용한 수분산 폴리우레탄(water-home polyurethane: WPU)의 제조에서 HTPB와 poly(propylene glycol)(PPG)을 혼합 사용한 음이온계 WPU와 쯔비터이온계 WPU를 제조하고 이들의 특성을 조사하였다. WPU 제조 시 HTPB 함량이 증가하면 입자 크기는 커지는 경향을 보이고, 폴리우레탄의 연질부와 경질부의 상분리는 증가하였다. 음이온계 WPU에 비하여 쯔비터이온계 WPU는 건조 필름의 분자간 수소 결합이 강해지는 경향을 나타내었다. 음이온계 및 쯔비터이온계 WPU는 공통적으로 건조 필름이 HTPB 함량이 폴리올 중 25 wt%일때 실험 범위에서는 신율과 인장 강도가 최대값을 보였으며, 이러한 특성은 폴리우레탄의 연질부와 경질부 사이의 미세 상분리를 반영한 것으로 판단되었다.

• Bulletin of the Korean Chemical Society
• /
• 제16권9호
• /
• pp.873-885
• /
• 1995

The local structural and thermodynamical properties of blends A-B/H of a diblock copolymer A-B and a homopolymer H are studied using the polymer reference interaction site model (RISM) integral equation theory with the mean-spherical approximation closure. The random phase approximation (RPA)-like static scattering function is derived and the interaction parameter is obtained to investigate the phase transition behaviors in A-B/H blends effectively. The dependences of the microscopic interaction parameter and the macrophase-microphase separation on temperature, molecular weight, block composition and segment size ratio of the diblock copolymer, density, and concentration of the added homopolymer, are investigated numerically within the framework of Gaussian chain statistics. The numerical calculations of site-site interchain pair correlation functions are performed to see the local structures for the model blends. The calculated phase diagrams for A-B/H blends from the polymer RISM theory are compared with results by the RPA model and transmission electron microscopy (TEM). Our extended formal version shows the different feature from RPA in the microscopic phase separation behavior, but shows the consistency with TEM qualitatively. Scaling relationships of scattering peak, interaction parameter, and temperature at the microphase separation are obtained for the molecular weight of diblock copolymer. They are compared with the recent data by small-angle neutron scattering measurements.

• 폴리머
• /
• 제25권3호
• /
• pp.385-390
• /
• 2001

oxyethylene/oxypropylene 공중합체의 존재하에 L-lactide를 중합시킴에 의해 poly(L-lactic acid) (PLLA) (A)와 polyether (B)로 이루어진 A-B-A block copoly(ester-ether)를 합성하였으며, 이들 블록 공중합체는 세그멘트를 도입함에 의해 PLLA에 유연성이 부여되었고, 표면에서의 미세상분리 구조로 인한 항혈전성의 개질을 확인하기 위하여 AFM사진을 관찰한 결과, PLLA와 비교하여 블록 공중합체는 필름표면의 요철성이 현저하게 저하하여 매끄러운 것을 확인하였으며 따라서, 표면의 요철이 항혈전성의 증가와 깊은 관계가 있음을 확인하였다.

• 폴리머
• /
• 제28권6호
• /
• pp.509-518
• /
• 2004

비대칭 블록 공중합체와 단일고분자로 구성된 블렌드의 미세 도메인 구조와 결정화 거동을 소각 X-선 산란, 광학 현미경 및 DSC를 사용하여 조사하였다. 본 연구에서는 폴리(메틸 메타크릴레이트) 블록의 무게 분률이 0.53인 폴리(메틸 메타크릴레이트)-폴리스티렌 이종 블록 공중합체 (PMMA-b-PS)를 저분자량 폴리(비닐리덴 플루오라이드) (PVDF)와 혼합하였다. PVDF 함량 증가에 따라 블렌드 미세구조가 라멜라에서 실린더 구조로 전이하였으며, PVDF의 결정화는 결정화 이전에 형성된 미세구조의 배열을 교란시켜 질서도가 낮은 형태를 야기시켰다. 또한, PVDF 결정화 거동은 PMMA 블록과의 혼화성 및 미세 도메인에 의해 부가되는 공간적 제한에 큰 영향을 받았다.

• Macromolecular Research
• /
• 제16권2호
• /
• pp.113-119
• /
• 2008

A series of amphiphilic dendrons n-18 (n: generation number, 18: octadecyl chain) based on an aliphatic polyether denderitic core and octadecyl peripheries were synthesized using a convergent dendron synthesis consisting of a Williamson etherification and hydroboration/oxidation reactions. This study investigated their thermal and self-assembling behavior in the solid state using differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) absorption spectroscopy, and small angle X-ray scattering (SAXS). DSC indicated that the melting transition and the corresponding heat of the fusion of the octadecyl chain decreased with each generation. FT-IR showed that the hydroxyl focal groups were hydrogen-bonded with one another in the solid state. DSC and FT-IR indicated microphase-separation between the hydrophilic dendritic cores and hydrophobic octadecyl peripheries. SAXS data analysis in the solid state suggested that the lower-generation dendrons 1-18 and 2-18 self-assemble into lamellar structures based upon a bilayered packing of octadecyl peripheries. In contrast, the analyzed data of higher-generation dendron 3-18 is consistent with 2-D oblique columnar structures, which presumably consist of elliptical cross sections. The data obtained could be rationalized by microphase-separation between the hydrophilic dendritic core and hydrophobic octadecyl peripheries, and the degree of interfacial curvature associated with dendron generation.

• Korean Chemical Engineering Research
• /
• 제57권3호
• /
• pp.392-399
• /
• 2019

A highly transparent interfacial layer (HTIL) to enhance the performance of dye-sensitized solar cells (DSSCs) was prepared via a polymer-assisted (PA) approach. Poly(vinyl chloride)-graft-poly(oxyethylene methacrylate) (PVC-g-POEM) was synthesized via atom-transfer radical polymerization (ATRP) and was used as a sacrificial template. The PVC-g-POEM graft copolymer induced partial coordination of a hydrophilic titanium isopropoxide (TTIP) sol-gel solution with the POEM domain, resulting in microphase separation, and in turn, the generation of mesopores upon calcination. These phenomena were confirmed using Fourier-transform infrared (FT-IR) spectroscopy, UV-visible light transmittance spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The DSSCs incorporating HTIL60/20 (consisting of a top layer with a pore size of 60 nm and a bottom layer with a pore size of 20 nm) exhibited the best overall conversion efficiency (6.36%) among the tested samples, which was 25.9% higher than that of a conventional blocking layer (BL). DSSC was further characterized using the Nyquist plot and incident-photon to electron conversion efficiency (IPCE) spectra.