서용석 교수

In order to get poly(vinylidene fluoride) (PVDF) films containing high beta-phase content, multiwalled carbon nanotubes (MWCNTs) were blended with PVDF. For drawn samples, the content of piezoelectric beta-form crystal was increased with MWCNT addition due to the rapid crystallization rate offered by the nucleating action of MWCNT, but soon reached a plateau. Poling on the drawn samples helps additional beta-phase formation when the added MWCNT content was less than 0.2 wt%; at this MWCNT amount

The characteristics of an electrorheological (ER) fluid, as a class of smart soft matter, can be actively and accurately tuned between a liquid- and a solid-like phase by the application of an electric field. ER materials used in ER fluids are electrically polarizable particles, which are attracting considerable attention in addition to further research. This perspective reports the latest ER materials along with their rheological understanding and provides a forward-looking summary of the poten

Magnetorheological (MR) fluids are a type of smart material with rheological properties that may be controlled through mesostructural transformations. MR fluids form solid-like fibril structures along the magnetic field direction upon application of a magnetic field due to magnetopolarization of soft-magnetic particles when suspended in an inert medium. A reverse structural transition occurs upon removal of the applied field. The structural changes are very fast on the order of milliseconds. The

[Image: see text] Lead zirconate titanate (PbZr(0.52)Ti(0.48)O(3), PZT) alloys have been extensively studied to be used for piezoelectric nanogenerators to harvest energy from mechanical motions. In this study, PZT nanofiber-based nanogenerators were fabricated to test their true piezoelectric performance without the triboelectric effect. Aligned PZT nanofibers were fabricated by a sol–gel electrospinning process. The thickness, area, and orientation of the PZT textile made by electrospinning a

In situ metallocence polymerization was used to prepare nanocomposites of multiwalled carbon nanotubes (MWCNT) and high density polyethylene (HDPE). This polymerization method consists of attaching a metallocene catalyst complex onto the surface of MWCNT followed by surface-initiated polymerization to generate polymer brushes on the surface. All the procedures of polymerization made progress with one-pot process. The morphological observation of nanocomposites using scanning electron microscopy

Aggregation behaviors, in particular, surface micelle formation, of a diblock copolymer A−B, where the A block is polystyrene (PS, surface inactive and water insoluble) and the B block is poly(methyl methacrylate) (PMMA, surface active, but water insoluble), at the air/water interface have been examined. The block length ratio of PS:PMMA was 140K:646K. With the aid of a Langmuir film balance and an atomic force microscope (AFM), surface pressure isotherms, as well as the hysteresis and temperatu

A new rheological model was applied to the analysis of the electrorheological behavior of a fluid containing silica nanoparticle-decorated polyaniline nanofibers. The model's predictions were compared with the experimental data, revealing that the proposed model correctly predicted the shear stress behavior both quantitatively and qualitatively. The shear stress data of the electrorheological fluid showing aligned fibers' structural reformation as a function of the shear rate agreed well with th

Diblock copolymer (A−B) behaviors in quasi-two-dimensional space have been examined where the A block is polystyrene (PS) and the B block is poly(methyl methacrylate) (PMMA). The length of the PMMA block was varied while that of the PS block was kept almost the same. The surface pressure isotherms were determined with the aid of a Langmuir film balance. The surface pressure isotherms exhibited two phase transitions attributed to surface micelle formation at low surface pressure and to further as

It was shown that a fine fibril structure of a thermotropic liquid crystalline polymer (TLCP)(poly(ester amide)) can be developed in a shear flow field of a thermoplastic matrix (polyamide, nylon 46) when the viscosity of the latter is lower than that of the former. Addition of a third component, a functionalized elastomer (maleic anhydride grafted ethylene−propylene−diene terpolymer, MA-EPDM) that interacts with the matrix polymer (nylon 46) and the thermotropic liquid crystalline polymer, faci