Studies of Frictional Properties on TN mode Alignment Film Surfaces with AFM/FFM

Kwak, Musun; Chung, Hanrok; Choi, Jee‐Hye; Kwon, Hyuk-Min; Kim, Jehyun; Han, Dong Keun; Park, Chulho; Lee, Sangmun; Lee, Chulgu; Cha, Sooyeol

doi:10.1080/15421400903050442

Cited by 6 publications

(4 citation statements)

References 13 publications

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“…Shindo et al measured the friction characteristics of the surface of CaSO 4 (001) and confirmed that a curved structure with a ridge-and-valley direction showed increased friction that curves with a smaller direction. 15 In addition, the friction characteristics also showed the same results for the surface of CaCO 3 (10)(11)(12)(13)(14). 16 In conclusion, it can be said that friction is caused by the potential interaction of the probe and surface element, and that it increases with increasing surface roughness [ Fig.…”

Section: Frictional Property By Rubbing Conditionmentioning

confidence: 69%

“…In the case of TN-mode AF, pre-bake showed frictional asymmetry in high-temperature fields, and this appeared to be because the tilt direction of the side-chain molecules were not uniform. 11 However, the friction loop of VA-mode AF shows stable data regardless of temperature [Figs. 2(a4)-2(e4)].…”

Section: Methodsmentioning

confidence: 99%

“…For TNmode AFs, the friction contrast due to the unevenness of the side chain was found for pre-bake temperature conditions. 11 However, there was no frictional asymmetry for the VA mode. 12 This can be interpreted as being due to the type of side chains and the influence of density, and in the case of the VA mode, the vertical direction of the polymer molecules create a stable side chain through intermolecular repulsion.…”

Section: Introductionmentioning

confidence: 95%

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Frictional properties of VA‐mode alignment‐film surfaces studied by frictional force microscopy

Kwak¹,

Chung²,

Kwon³

et al. 2010

J Soc Info Display

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The surface-friction characteristics of the post-bake temperature were compared to that of the rubbing condition on VA-mode alignment films (AFs) using frictional force microscopy (FFM). The surface roughness and the surface frictional force increased when the temperature was elevated. However, the frictional asymmetry could not be detected by the frictional loop due to the instability of the side-chain molecular arrangement. For the inter-influences of the total friction and surface roughness, the density of the side chain was changed and it was intentionally rubbed for evaluation. The results showed that the total friction was higher when the rubbing was stronger and side-chain density lower, and the surface roughness also increased in the same manner. This can be explained by the potential interaction due to the curved structure of the side-chain surface that establishes the probe that is scanned and the top surface layer. In order to confirm the influence of the pre-tilt angle on the tilt of the side chain, a test cell was produced under the same conditions and evaluated. The results showed that the pre-tilt-angle decreased according to the difference in density of the side chain and strength of rubbing after injecting liquid-crystal (LC). FIGURE 1 -(a) The principle of AFM/FFM. (b), (c) The density of side chain molecular on PI layer surface. Sample 2 has half density of side chain compared with sample 1. The samples of this experiment were artificially applied rubbing condition and the probe scanned along the rubbing direction.

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Section: Frictional Property By Rubbing Conditionmentioning

confidence: 69%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

See 1 more Smart Citation

Frictional properties of VA‐mode alignment‐film surfaces studied by frictional force microscopy

Kwak¹,

Chung²,

Kwon³

et al. 2010

J Soc Info Display

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“…5 As the technology for the examination of LC orientation evolves, more enhanced analysis is required to interpret the polymer-layer structure. 6,7 Recently, the blue phase (BP) has been recognized as a high-speed liquid crystal. The development of the polymerstabilized blue phase (PSBP) 8 has lead to more research on the application of this new display mode.…”

Section: Introductionmentioning

confidence: 99%

Study of polymer‐network structure on polymer‐stabilized blue phase

Kwak¹,

Park²,

Jeon³

et al. 2011

J Soc Info Display

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After removing liquid crystals (LCs) using hexane cleansing solution, polymer network (PN) structure of polymer stabilized blue phase (PSBP) was analyzed. PN type had different shape in the surface region (nearby glass) and intermediate region. Directly measured PN structure and theoretical polymer line defect on the cubic symmetry were compared. Moreover, analysis of different kind of LC and monomer, PN appeared in membrane state.Keywords polymer stabilized blue phase (PSBP), polymer network structure (PNS), defect, hexane, display. pinning effect. P-80 / M. Kwak SID 2013 DIGEST • 1287

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Stratified Polymer Grafts: Synthesis and Characterization of Layered ‘Brush’ and ‘Gel’ Structures

Ramakrishna

Nalam

et al. 2013

Adv Materials Inter

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The development of surface coatings with well-defi ned architecture is of particular interest in several disciplines, notably in biomaterials. Bio-organic layers on different length-scales, featuring variable composition, structure and modulus have been observed in several biological systems, such as human cartilage, mammalian skin and the nacre of oyster shells. [1][2][3] These complex systems often consist of mechanically graded structures that resist and respond to external normal and shear forces, and therefore protect underlying tissues from incurring any damage. As an example, the human epidermis consists of keratinizing epithelial cells-an elastic layer with low modulus-buried under a layer of dead cells, the stratum corneum , with higher modulus. The stratifi ed epithelium thus acts as the body's major barrier against abrasion and inhospitable environments. [ 4,5 ] In order to mimic mechanically useful structures found in nature, materials scientists have been made numerous efforts to fabricate coatings with discontinuous mechanical properties at pre-determined depths in a single multilayered architecture. These materials, unlike homogenous fi lms, have been shown to successfully redistribute contact stresses at the interface and to resist failure-inducing contact deformations. [ 6,7 ] Progress has also been made in fabricating graded morphologies of organic/ inorganic nanocomposites, thereby mimicking the approach of natural counterparts, to obtain coatings with higher toughness and modulus. [ 8 ] Despite all these efforts, the fabrication of a full-organic, polymer-based coating architecture featuring nanoscale variations of properties still represents a challenging task in polymer and materials science.The development of surface-initiated polymerization (SIP) techniques [ 9 ] has provided a promising path towards the stepwise fabrication of stratifi ed polymer fi lms. To this end, controlled-radical SIP methods incorporating sequential polymerization processes can be applied. [ 10 ] With the exception of the pioneering work of Tsukruk et al., [ 11 ] which introduced prototypes of stratifi ed polymeric fi lms, few such investigations have been reported. Moreover, the full characterization of stratifi ed fi lms, i.e. the physical and chemical analysis of the fi lm properties at different depths (for each stratum), on the supporting substrate certainly represents a challenging experimental task. Although real-space analytical techniques, such as atomic force microscopy (AFM), enable access to surface properties in two dimensions, determination of physical properties in the third dimension (from surface to bulk) can be more readily achieved by reciprocal-space-based techniques, such as grazing-incidence, small-angle scattering (GISAS), or X-ray and neutron refl ectivity-these methods are, at present, among the few that could determine the density profi le of materials perpendicular to the sample surface. However, probing the vertical architecture of polymeric nanofi lms with such techniques normally requir...

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Studies of Frictional Properties on TN mode Alignment Film Surfaces with AFM/FFM

Cited by 6 publications

References 13 publications

Frictional properties of VA‐mode alignment‐film surfaces studied by frictional force microscopy

Frictional properties of VA‐mode alignment‐film surfaces studied by frictional force microscopy

Study of polymer‐network structure on polymer‐stabilized blue phase

Stratified Polymer Grafts: Synthesis and Characterization of Layered ‘Brush’ and ‘Gel’ Structures

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