By Roger Corneliussen
Controlled Nanostructures
U.S. Patent 8,481,164 (July 9, 2013), “Materials Having Predefined Morphologies and Methods of Formation Thereof,” Jennifer Nam Cha, James Lupton Hedrick, Ho-Cheol Kim, Robert Dennis Miller, and Willi Volksen (International Business Machines Corporation, Armonk, New York, USA).
Materials with specific nanostructures could be useful, but they are difficult to produce economically, precisely, and in large quantities. Cha et al. made controlled nanostructures using self-assembling block copolymers containing a crosslinkable polymer. An example is a polystyrene-block-poly(ethylene oxide) material containing a crosslinkable polymer, poly(methylsilsesquioxane), miscible with the oxide block. Solutions of the material are spin casted to form a film. The film is annealed with a solvent vapor at room temperature for 10 to 15 hours. Specific morphologies were produced, including 1- to 500-nm nanopores and nanolamellae. The nanostructures are determined by copolymer composition and curing agent content.
Plasma Treating Foams
U.S. Patent 8,475,724 (July 2, 2013), “Method and Apparatus for Plasma-Treating Porous Body,” Koichi Kono, Kotaro Kimishima, and Kazuki Kiso (Toray Battery Separator Film Co., Ltd., Tochigi, Japan).
Plasma treatment is often used to modify surfaces of materials, such as hydrophilizing hydrophobic materials. However, it is difficult to treat inner pore surfaces of foams to the same extent as the exterior surfaces. Kono et al. solved this problem by pushing the plasma reactants through a foam using a vacuum. The foamed film, sheet, or plate is placed on a porous support. The plasma is formed and the reactive gas sent flowing over the foam. The other side of the porous support is evacuated with an aspirator or vacuum pump at 5- to 50-Pa pressure, forcing the plasma through the foam and reacting with the inner surfaces.
Orientating Fillers
U.S. Patent 8,475,703 (July 2, 2013), “Method of Orientating Fillers in Composite Materials,” Lih-Sheng Turng, Larry R. Holmes, Jr., Yiyan Peng, and Xiaochun Li (Wisconsin Alumni Research Foundation, Madison, Wisconsin, USA).
Filled and reinforced plastics are very common high-performance materials. However, locally tailored composites with different properties in different locations, known as functionally graded materials, are desired for special applications. Turng et al. controlled filler orientation during processing using electric fields. Fillers or fibers are arranged in a matrix material either by rapid prototyping or mold placement. The mold is fixed and a directional electric field is applied, aligning fillers and fibers. A portion of the matrix is cured with the desirable filler or fiber orientation. The procedure can be repeated layer by layer until completion. Candidate fillers include aluminum and alumina microparticles and multi-walled carbon nanotubes.
Uniform Microparticles
U.S. Patent 8,470,398 (June 25, 2013), “Method for Producing Single-Hole Hollow Polymer Microparticles,” Hiroshi Yamauchi and Yasuyuki Yamada (Sekisui Chemical Co., Ltd., Osaka, Japan).
Microparticles on the order of microns are useful for lightweight structures, heat insulation, cushioning, and selective light absorption. However, these applications require very uniform microparticle sizes. Preparation by suspension polymerization is commonly used to prepare microparticles, but adequate uniformity is difficult, requiring elaborate classification processing.
Yamauchi and Yamada produced single-hole hollow polymer particles with extremely uniform dimensions without need for special classification operations. A dispersion of swollen particles is prepared by mixing seed particles in water with an oil-soluble solvent. The seed particles absorb the solvent. A water soluble polymer and crosslinkable monomer is added to the suspension and precipitated onto the suspended swollen particles. After curing, the particles are washed with water, and the oil soluble solvent is vaporized. The particles’ inner and outer diameters are extremely uniform, with outer diameters ranging from 0.1 to 100 microns while the inner diameters range from 10 to 99% of the outer diameters.
Shape-Memory Polymers
U.S. Patent 8,470,935 (June 25, 2013), “Shape-Memory Resin, Molded Product Composed of the Resin, and Method of Using the Molded Product,” Midori Shimura, Kazuhiko Inoue, and Masatoshi Iji (NEC Corporation, Tokyo, Japan).
The pressure for renewable materials is growing. Polylactic acid (PLA) is a candidate renewable material with a 150-180°C melting point and a strength comparable to polystyrene. However, PLA is more expensive than petroleum-based resins, without having any mechanical properties superior to those of competitive petroleum-based resins. To make PLA materials cost effective, new functions must be added. Shimura et al. developed a PLA resin with a three-dimensional structure and shape memory features. This PLA derivative having two or more crosslinking functional groups results in flexible polymers with a low Tg (less than 30°C). The crosslinks provide a shape-recovering ability and excellent strength. This material is suitable for wearable electronics in which shapes can be molded and reformed easily by users.
Impact Modifiers
U.S. Patent 8,466,214 (June 18, 2013), ”Core-Shell Impact Modifiers for Transparent Polymer Matrices,” Rosangela Pirri and Philippe Hajji (Arkema France, Colombes, France).
Impact modifiers are often added to brittle materials to increase impact strength. These modifiers are usually rubber particles which, unfortunately, reduce transparency because of light scattering. Particle size is a critical factor because particles below a critical size do not scatter light. Pirri and Hajji reduced the size of core-shell impact modifiers by reducing the size of the core by radical emulsion polymerization in the presence of a sulfur additive. They were able to produce a suspension of particles with diameters less than 50 nm. It seems the sulfur additives are grafted to the growing particles, improving colloidal stability and reducing particle sizes. The resulting modifiers can toughen transparent materials without affecting transparency.
Automated Injection Molding Controls
U.S. Patent 8,460,586 (June 11, 2013), “Injection Molding Method and Apparatus for Controlling a Mold Temperature and Displacement of an Injection Screw,” Toshihiko Kariya, Michitaka Hattori, Shigeru Nozaki, and Satoshi Imaeda (Mitsubishi Heavy Industries Plastics Technology Co., Ltd., Nagoya-shi, Aichi, Japan).
Conventional injection molding requires trial-and-error skills for optimizing mold temperature and the molding process. Automation usually is based on single property measurements, which obscures other important features of the process. Kariya et al. developed a computer control system based on correlations between property waveforms and the settings, without relying on any single property value. Once the optimum waveforms are developed, the system automatically changes settings to conform to the desired waveforms.
Biodegradable Macromonomers
U.S. Patent 8,492,505 (July 23, 2013), ”Branched Biodegradable Polymers, a Macromonomer, Processes for the Preparation of Same, and their Use,” Jan Feijen, Zhiyuan Zhong, and Pieter Jelle Dijkstra (University of Twente, Enschede, Netherlands).
Branched biodegradable polymers are needed for medical and non-medical applications. A biodegradable macromonomer is needed for preparing different biodegradable materials for specific applications. Feijen et al. developed branched biodegradable polymers by preparing a macromonomer by ring-opening polymerization of at least one cyclic ester, cyclic carbonate, or cyclic carboxyanhydride with a branching agent and a catalyst, followed by polycondensation of the macromonomer with other monomers by ring-opening polymerization to form the final material.
Biogenic Silica
U.S. Patent 8,492,444 (July 23, 2013), “Biogenic Silica from Silica-Containing Plant Material such as Rice Hulls,” Neal A. Hammond and J. Steve Peirce (St. Louis, Missouri, USA).
Silica is a common filler for plastics. Recent U.S. legislation has prohibited the use of synthetic silica in organic foods. Amorphous silica is produced by plants, such as sugar cane and rice. The rice plant contains 11-23% silica, compared to about 1-2% in most plants, preventing its use in animal feeds. Hammond and Peirce produced biogenic silica from rice hulls and rice straw for use as an anti-caking agent, excipient, or flavor carrier. Since the plant material is certified as organic, the silica is also certified as organic. The plant material is ground and the silica concentrated by enzyme treatment or burning.
Light-Emitting Polymers
U.S. Patent 8,487,055 (July 16, 2013), “Hole Transport Polymers,” Nora Sabina Radu, Gene M. Rossi, Eric Maurice Smith, Yulong Shen, Weiying Gao, Reid John Chesterfield, Jeffrey A. Merlo, Daniel David Lecloux, and Frederick P. Gentry (E. I. du Pont de Nemours and Company, Wilmington, Delaware, USA).
In organic photoactive electronic devices, such as light-emitting diodes, an active organic layer is sandwiched between two electrodes. This material then emits light by an electrical voltage. There is a continuing need for improved charge transport materials for these diodes. Radu et al. developed an improved material based on aromatic chains containing alkyl, fluoroalkyl, aryl, fluoroaryl, alkoxy, aryloxy, and crosslinkable groups. The polymer chains are produced by Yamamoto polymerization using zero-valent nickel compounds. A crosslinkable film is formed between two electrodes. After fabrication, the film is cured by heat or radiation to form a more robust, less-soluble film for the light-emitting diode.
Microdomain Orientation
U.S. Patent 8,491,965 (July 23, 2013), “Method of Controlling Orientation of Domains in Block Copolymer Films,” Joy Cheng, Ho-Cheol Kim, Daniel P. Sanders, and Linda Sundberg (International Business Machines Corporation, Armonk, New York, USA).
Block copolymer films can be used in which phase separation forms nanoscale structures by phase-separating microdomains. One problem is controlling the orientation of the assembled microdomains which tend to organize into randomly oriented nanostructures. Cheng et al. oriented microphase-separated domains with a control agent. This control agent typically coats the surface and controls microphase orientation by interaction with the solidifying block copolymer. For example, a control agent for poly(styrene-b-methyl methacrylate) di-block copolymer is a random copolymer of styrene and methyl methacrylate. A melt of the two polymers is put in contact with a surface and cooled. The random copolymer preferentially coats the surface and induces oriented phase separation in the block copolymer.