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An artificial muscle actuator resolves practical engineering problems in compact wearable devices, which are limited to conventional actuators such as electromagnetic actuators. Abstracting the fundamental advantages of an artificial muscle actuator provides a small-scale, high-power actuating system for developing varifocal augmented reality (AR) glasses and naturally fit haptic gloves. Here, we design a shape memory alloy (SMA)-based lightweight and high-power artificial muscle actuator, the so-called compliant amplified SMA actuator (CASA). Despite its light weight (0.22 g), the CASA has a high power density of 1.7 kW/kg and an actuation strain of 300%. We show how CASA enables image depth control and an immersive tactile response in the form of AR glasses and haptic gloves whose thin form factor and high power density can hardly be achieved by conventional actuators.

The eye-box expansion method using the merging of waveguide and HOE (holographic optical element) is presented. Using the waveguide with the refractive index of 1.7, the wide FoV (field of view) that is up to 60° is achieved. Full color and wide FoV are obtained using 2 waveguides. Projection optical system based on Scheimpflug principle is proposed and designed to compensate large-scale off-axis HOE aberrations. In order to enhance image quality, the projection system is precisely simulated and the grating pitch and alignment are calculated to increase the eye-box and uniformity.

The coherent backlight unit (C-BLU) using a diffractive optical element (DOE) for full-color flat-panel holographic display is proposed. The coherent backlight unit is composed of two diffractive optical elements (DOEs) that are imprinted on the same glass substrate. The illumination area of the backlight is 250 mm x 130 mm and the thickness is 2.2 mm, which is slim compared to other conventional coherent backlight units for holographic display systems. In experiments, the total efficiency is measured as 0.8% at red (638 nm), 3.9% at green (520nm), and 3.4% of blue (473 nm). As a result, we could get the 10 inch full color holographic display with 4k resolution.

The novel design for the compact augmented reality (AR) glasses that utilize holographic optical element (HOE) as a combiner is presented. The wide field of view (FoV) that is larger than 90°, full color and high contrast ratio (CR) are achieved based on the single layer HOE, which has the thickness of 25 μm. In order to implement compactness of AR glasses using HOE combiner, the combination of optical lenses is proposed. In this design, a chromatic aberration and astigmatism, which are caused by highly off-axis projection of the image onto HOE, and the precise wavefront reproduction that maximize the efficiency of the HOE are taken into account simultaneously. The geometrical image distortion is corrected by implementation of image pre-distortion algorithm. The interpupillary distance (IPD) adjustment is applied to compensate small eye box. Based on the design, wearable prototype is introduced. Through the experiments both on benchtop and prototype, at the distance of 2 m, large image with diagonal of 150 inches is displayed.

We report the glasses-type device for augmented reality. By utilizing holographicdisplay method and designing compact optical system, we removed usual discomfort in existing AR apparatus, and developed the approach to the ideal display.

Based on reversible photo crosslinkable properties, a series of polymethacrylate derivatives having cinnamoyl group in the side chain has been designed and synthesized. By simple UV irradiation and thermal treatment on these polymer films, a complete healing behavior accompanied by changes of the surface hardness was observed.

Poly(1-oxotrimethylene) (POTE) was prepared by polymerization of ethylene and carbon monoxide gases in an autoclave using a palladium catalyst system. POTE fibers having different draw ratios were prepared and characterized using differential scanning calorimetry (DSC), X-ray diffraction, and a universal testing machine (UTM). Tensile strength and modulus of POTE fibers having a draw ratio of 16 obtained by drying at 220 °C were found to be 13.4 and 369.8 g/denier, respectively. These values are much larger than those of poly(ethylene terephthalate) (PET) and Nylon 6 fibers that are currently used as tire cords. Open image in new window

Silver-perfluorodecanethiolate complexes having superhydrophobic, antifouling, antibacterial properties were prepared by a reaction of silver nitrate with perfluorodecanethiol. When the silver nitrate to perfluorodecanethiol molar ratio was 1/2, silver-perfluorodecanethiolate complexes having hierarchical micro-/nano-sized wire shapes were obtained, and they showed superhydrophobic and antifouling properties. After UV irradiation, silver nanoparticles were generated on the wires and exhibited antibacterial properties.

A series of poly(thiophene) derivatives with decyl-oligo(oxyethylene) side groups, (PDnET) is synthesized via oxidative coupling polymerization. PD3ET and PD4ET with longer oligo(oxyethylene) units exhibited a liquid crystalline phase with well-ordered lamella structures, although PD3ET showed a more ordered structure than PD4ET. PD1ET and PD2ET have shorter oligo(oxyethylene) groups than PD3ET and show less-ordered structures with liquid-crystalline phase observed. The UV-vis spectra indicated that the maximum absorption wavelengths of PDnET increase when the number of oxyethylene units increases from 1 to 3; however, the maximum absorption wavelength of PD4ET is lower than that of PD3ET. Therefore, the most ordered and conjugated structures are obtained when the number of oxyethylene units is three.

Phase-separated surfaces of blends of polystyrene (PS) and well ordered comb-like polymer, poly[(oxy(decylsulfonylmethyl)ethylene)] (CH 3 -10SE), were prepared by spin casting polymer mixtures. Various surface morphologies, such as holes, islands, connected islands and pillars, were prepared by changing the blend compositions. Due to the influence of the CH 3 -10SE domain with a well ordered molecular conformation, a very low energy surface (≈22 mN/m) was created, which is close to the value of the pure polymer (≈20 mN/m), even when the blends contained only 20 wt.% of the pure polymer. Furthermore, by selective etching the PS domain in the blend surfaces, the advancing contact angles of water and n -hexadecane were highly increased from 113.5° and 43.2° for the pure CH 3 -10SE surface to 133.3° and 67.2° for the CH 3 -10SE structural surfaces with holes prepared using the solvent etching method, respectively. The result of the water advancing contact angles measured on the samples immersed in water over 20 days showed that the film stability of CH 3 -10SE could be improved considerably by even adding small amounts of PS.

A series of comb-like fluorinated poly(oxyethylene)s having different content of fluoroalkyl side group were prepared to examine the effect of the surface structure variation on the surface properties. When the thin films of the polymers having ≥58 mol % of fluoroalkyl side groups were annealed, surface energy decreased and surface stability against polar liquids improved. This surface property behavior was found to be very well correlated with changes of the paracrystalline structure orientation and scattering unit numbers after the annealing process. However the average tilt angle and d spacing of the fluoroalkyl side group and the paracrystalline ordering of the thin films did not change, if any, after the annealing process. Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and grazing incidence X-ray diffraction (GIXD) were used to determine the surface structure, and contact angle measurements were conducted to measure the surface properties.

Comb-like fluorinated polymers with different backbone structures, poly(heptadecafluorodecyl acrylate) (PA-Rf), poly[oxy[(2-perfluorooctylethylene)thiomethyl]ethylene] (PEO-Rf), and poly[p-[[(perfluorooctylethylene)thio]methyl]styrene] (PS-Rf), were used as surfactants in dispersion polymerization to examine the effect of backbone structure on the formation of polymer particles. Dispersion polymerization of monomers with different polarities using these comb-like fluorinated polymer surfactants in CO2 showed that PEO-Rf containing a polar oxyethylene backbone was an effective surfactant for the dispersion polymerization of a polar monomer, such as N-vinyl-2-pyrrolidone, whereas PA-Rf was effective for less polar monomers, such as methyl methacrylate and N-vinyl caprolactam.

The surface properties of comb-like polymer blends of poly(oxyethylene)s having CH3-terminated and CF3-terminated alkylsulfonylmethyl side chains were studied. These side chains were found to be well oriented on the surface of the blends, while being phase separated, forming various surface morphologies composed of holes, islands, or connected islands, because of their immiscibility resulting from their different polarities. The domain size of each polymer on the blend surface was found to be almost linearly proportional to the bulk compositions of the mixture, and the CF3-terminated alkylsulfonylmethyl side chain domains were found to be located in the lower region of the surface. The polar CF3-terminal groups in the lower regions were deemed to control the surface properties, because the contact angles and stick–slip behaviors of the blends containing more than 40 mol% of poly(oxyethylene) with CF3-terminated side chains were almost identical.

Polyepichlorohydrin containing reactive chloromethyl side groups was found to be highly soluble in polar ionic liquids containing halide anions such as 1-n- butyl-3-methyl imidazolium chloride, 1-n-ethyl-3-methyl imidazolium bromide, and 1-n-hexyl-3-methyl imidazo- lium chloride, whereas it was insoluble in less polar ionic liquids such as 1-n-butyl-3-methyl imidazolium tetrafluor- oborate and 1-n-butyl-3-methyl imidazolium hexafluoro- phosphate. The reaction of polyepichlorohydrin with thiolates and thiol compounds in the polar ionic liquids as reaction media produced polyoxyethylenes with thio- ether side groups in very high conversions and yields. When polyepichlorohydrin was reacted with sodium 1H,1H,2H,2H-perfluorinated decanethiolate in 1-n-hexyl- 3-methyl imidazolium chloride at 70 � Ca nd the product was separated through centrifugation, the ionic liquid could be used more than four times, and high conver- sions (>70 mol %) and yields (>62 wt %) were main- tained. V C 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 132-138, 2009

Comb-like fluorinated polystyrenes with different side chain interconnecting groups between backbone and side chain, such as ether (PST−O), thioether (PST−S) and sulfone (PST−SO2), were synthesized in order to examine the effect of the interconnecting groups on the surface order and properties. Near edge X-ray absorption fine structure spectroscopy and grazing incidence wide-angle X-ray diffraction showed that PST−SO2 with very polar sulfone groups exhibited a lower tilt angle of the fluorinated helix to the surface normal as well as higher packing density of fluorinated alkyl side chains than PST−O and PST−S, which have less polar groups. As a result of the ordered structure at the polymer-air interface, PST−SO2 has a smaller surface energy and better stability in water than PST−O and PST−S. These results suggest that the introduction of polar groups to the side chains of comb-like fluorinated polymers can improve the surface properties including the hydrophobicity and stability of fluorinated surfaces.

We propose slim coherent backlight unit for a mobile holographic display. This backlight unit consists of glass substrate for waveguide and two surface gratings produced by two-beam interference. The area of backlight illumination is 150 by 85 mm, and the thickness is 0.7 mm, which is thin compared to other conventional coherent backlight units. This backlight unit exhibits a total efficiency of 0.1%, preserving the collimation and a uniformity of 80% over the whole area. The proposed slim coherent backlight can be applied to a mobile holographic display.

The surfaces of comb-like poly(oxyethylene) derivatives with n-alkylsulfonyl side groups were more effective at reducing Pseudomonas aeruginosa adhesion than the surfaces of common materials such as polystyrene, poly(methyl methacrylate), poly(dimethylsiloxane), fluorinated polyacrylate, and glass. When the comb-like poly(oxyethylene) was mixed with polystyrene and poly(methyl methacrylate), the topology and roughness of the surfaces varied according to the mixture compositions. However the surface energies of the mixtures were close to that of the comb-like poly(oxyethylene) in the range of 21-23 mN/m and bacterial adhesion resistances of the mixture surfaces were also comparable to that of the pure comb-like poly(oxyethylene) surface.