A flow-focusing geometry is integrated into a microfluidic device and used to study drop formation in liquid–liquid systems. A phase diagram illustrating the drop size as a function of flow rates and flow rate ratios of the two liquids includes one regime where drop size is comparable to orifice width and a second regime where drop size is dictated by the diameter of a thin “focused” thread, so drops much smaller than the orifice are formed. Both monodisperse and polydisperse emulsions can be produced.

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Formation of dispersions using “flow focusing” in microchannels

The photopolymerization of mixtures of multifunctional thiols and enes is an efficient method for the rapid production of films and thermoset plastics with unprecedented physical and mechanical properties. One of the major obstacles in traditional free-radical photopolymerization is essentially eliminated in thiol–ene polymerizations because the polymerization occurs in air almost as rapidly as in an inert atmosphere. Virtually any type of ene will participate in a free-radical polymerization process with a multifunctional thiol. Hence, it is possible to tailor materials with virtually any combination of properties required for a particular application. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5301–5338, 2004

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/pola.20366

Thiol–enes: Chemistry of the past with promise for the future

Role of Structural Factors in the Nonlinear Optical Properties of Phthalocyanines and Related Compounds

An Internet billing method comprises establishing an agreement between an Internet access provider and a customer, and an agreement between the Internet access provider and a vendor, wherein the Internet access provider agrees with the customer and the vendor to bill the customer and remit to the vendor for products and services purchased over the Internet by the customer from the vendor. The provider creates access to the Internet for the customer. When the customer orders a product or service over the Internet from a vendor, transactional information transmitted between the customer and the vendor is also transmitted to the provider. The provider then bills the transaction amount to the customer and remits a portion of the transaction amount to the vendor, keeping the differential as a fee for providing the service. As a result of this method, there is no need for any customer account numbers or vendor account numbers to be transmitted over the Internet, thereby maintaining the security of that information.

Internet billing method

Phthalocyanines: old dyes, new materials. Putting color in nanotechnology

Copolymers of azo dye substituted acrylic monomer and methylmethacrylate are synthesized and their third‐order nonlinear optical susceptibility χ(3) is evaluated using the third harmonic generation Maker fringe method. The χ(3) is 1.26×10−12 esu at 25.9 mol % azo dye monomer content in the copolymer. It is also shown that there is a linear relationship between χ(3) and the monomer content.

Nonlinear optical properties of an azo dye attached polymer

Several organic materials with a bulky donor group have been developed for second‐order nonlinear optics. Among these materials, 2‐adamantylamino‐5‐nitropyridine (AANP) crystal has the largest second‐order nonlinear optical coefficient. By second‐harmonics measurement at 1.064 μm, coefficients of d31 and d33 were determined to be 80 and 60 pm/V, respectively. Angle‐tuned phase‐matched second‐harmonic generation with a conversion efficiency=2×10−3 W−1 has been demonstrated using a 1 mm AANP bulk crystal at 1.064 μm.

Nonlinear optical properties of 2‐adamantylamino‐5‐nitropyridine crystals

Fine droplets of nematic liquid crystal (LC) with a diameter less than 100 nm were obtained in ultraviolet curing polymers. The transparency of the material was kept high in the infrared regions because there was little scattering in comparison to materials containing much larger droplets. The fine droplets were found to respond to an electric field, causing a change in birefringence. This change was about 0.0004 at the applied voltage of 5.5 V/μm. The special features of low transmission loss and easy film formation will enable one to apply LCs to optical devices of the wave guide type.

Fine droplets of liquid crystals in a transparent polymer and their response to an electric field

Fabry-Perot etalon type tunable wavelength-selective filter comprises: a first layer including a transparent electrode and an optical mirror layer; a third layer including a transparent electrode and an optical mirror layer; and a second layer which is composed of a material with a refractive index variable with electric field, and sandwiched between the first layer and the third layer, wherein the material having a refractive index variable with electric field is composed by dispersing liquid crystal droplets equal to or less than 150 nm in diameter in a light transmissive characteristic medium such as a polymer or silica glass, and by adding plasticizer therein. In this structure, the optical mirror layer consists of a dielectric multilayer mirror with an optical reflectance of equal to or more than 95% for 1.5 μm wavelength light, and the glass substrate has a finishing surface precision of equal to or less than λ/10, where λ is a wavelength of light that traverses the tunable wavelength-selective filter.

Tunable wavelength filter using nano-sized droplets of liquid crystal dispersed in a polymer

We studied the third‐order nonlinear optical properties of phthalocyanine and fullerene in solution and in thin film form through third‐harmonic generation measurement. X‐ray diffraction measurement and scanning electron microscopy observation were also conducted to investigate the relationship between nonlinear optical and structural properties of the thin film. The nonlinearities depend on the π‐conjugated length and the introduction of a central metal atom. We clarify the factors for forming suitable thin films by organic molecular beam deposition. It is shown that both the crystal structure and molecular alignment can be controlled to enhance the nonlinearities of the phthalocyanine thin film, thereby providing the maximum third‐order susceptibility of 3.0×10−10 esu. We show that nonlinearities of the thin films can be estimated experimentally from those of solutions.

Shiro Matsumoto

Papers

Nonlinear optical properties of an azo dye attached polymer

Nonlinear optical properties of 2‐adamantylamino‐5‐nitropyridine crystals

Fine droplets of liquid crystals in a transparent polymer and their response to an electric field

Tunable wavelength filter using nano-sized droplets of liquid crystal dispersed in a polymer

Third‐order nonlinear optical properties of phthalocyanine and fullerene