University of Massachusetts Amherst

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COLORIMETRIC RADIATION SENSORS
Researchers at UMass Amherst have developed sensors for detection of ionizing radiation (e.g. X-ray, gamma ray, and electron beam radiation) based on polymer multilayer films. A radiation sensor includes a substrate and a polymer multilayer film including alternating layers of a high refractive index polymer and a low refractive index polymer that give rise to reflected structural color in the visible region of the spectrum. The high refractive index polymer and the low refractive index polymer each comprise repeat units derived from a photo-crosslinkable monomer. A variety of rigid and flexible substrates can be used to fabricate sensors (for example, Figure 1 shows a multilayer polymer fabricated on a Mylar sheet), and polymer multilayer films can be designed to undergo either a blue or red shift (see Figure 2) in response to ionizing radiation. The radiation sensors are useful in preparing various articles, including wearable patches, packaging materials, labels, and window panes.
Published: 6/19/2015   |   Inventor(s): Ryan Hayward, Maria Chiappelli
Category(s): Healthcare, Devices & sensors, Material science
General method for well-dispersed polymer nanocomposites by photografting in solution
This invention concerns a simple method for dispersing nanoparticles within a polymer matrix. Nanoparticles can impart beneficial properties to polymer matrices, but these enhancements depend sensitively on the level of distribution of particles. The invention uses random copolymers that can be easily grafted to nanoparticles with reactive moieties (Fig A). These design features promote interactions between copolymers and nanoparticles, leading to a well-dispersed polymer matrix (Fig B). Other approaches rely on attraction between polymer functional groups and nanoparticles or utilize end-grafted homopolymers. The former approach relies on compatible chemistry between the functional groups and nanoparticles, and is not easily generalized to different particle and polymer matrix chemistries. With the end-grafted homopolymer approach, it can be synthetically challenging to achieve good particle dispersion. By contrast, the random copolymer grafting approach is generalizable to a wide range of polymer and particle combinations and synthetically simple. 

Published: 4/10/2015   |   Inventor(s): Ryan Hayward, Adam Hauser
Category(s): Material science, Nanotechnology, Engineering
Enhanced Charge Transport Through Nanoconfinement
A team of accomplished researchers at the University of Massachusetts Amherst has discovered a novel pathway for enhancing anhydrous proton transport in polymeric materials. This pathway entails generating supramolecular nanoscale confinement in polymers containing anhydrous proton transport functionalities. By carefully designing the polymer structures, the proton transport moieties of the polymers can be confined and organized within the nanoscale domains of the polymers via self-assembly, resulting in enhanced proton transport capabilities. This enhancement improves the conductivity of the polymers by 2-3 orders of magnitude. The high conductivities observed for the polymers with nanoconfinements are correlated with their ability to form locally high concentrations of proton transport moieties. These polymers allow high conductivities at high temperatures, which can increase fuel cell efficiency, lower cost, simplify heat management, and provide better tolerance of the fuel cell catalysts against poisoning.
Published: 11/19/2014   |   Inventor(s): Ryan Hayward, Sankaran Thayumanavan, Mark Thomas Tuominen
Category(s): Material science, Nanotechnology, Physical Science, Devices, Clean Energy
TUNABLE SURFACE WRINKLES FOR SMART ADHESION
This invention provides a novel, reusable adhesive surface with a well-defined surface wrinkle pattern as well as a facile, scalable and economical method to directly fabricate a patterned adhesive using a bottom-up approach. The patterning process involves swelling a laterally confined polymer film to develop surface wrinkles and photopolymerizing the swelling agent to stabilize the wrinkles. The control of adhesion is determined by the wavelength of the surface wrinkles, which is directly proportional to the thickness of the polymer film. Various processing parameters such as the film thickness, the polymer or swelling agent material, and the degree of lateral confinement can be adjusted to tune and control adhesion to produce truly "smart" adhesives for a variety of commercial applications.
Published: 11/18/2014   |   Inventor(s): Edwin Chan, Alfred Crosby, Ryan Hayward
Category(s): Material science, Engineering, Physical Science