Search Results - alfred+crosby

This invention demonstrates a strong bottlebrush pressure sensitive adhesives that is >6 times stronger than commercial VHB1000 tape and is capable of indefinite cycles of wet-dry-wet adhesion (tested up to 50 cycles, 1 month apart). The  pressure sensitive adhesives were engineered using the defect-driven design philosophy (D3) where the number of defects in the system is maximized by purposely building large dangling defects into synthesized networks.

This technology, developed by a team of polymer scientists at the University of Massachusetts Amherst, provides a versatile and simple method for producing highly resilient synthetic hydrogels with excellent mechanical properties comparable to the most efficient, naturally occurring elastic protein called resilin. The method involves the use of photo-initiated crosslinking reaction of hydrophilic and hydrophobic polymers having reactive end-groups in the presence of a tetra-functional thiol cross-linker. The resultant resilient hydrogels possess network elements of resilin, including a uniform network structure, low crosslink density, and an absence of secondary structures within the crosslinked primary chains. These hydrogels are capable of undergoing significant reversible deformation without energy loss (?97% resilience) at varying water content and show negligible hysteresis across a broad range of strains up to 300%. The swelling capacity, stiffness and fracture toughness of the hydrogels can be easily tuned by controlling the volume fractions of the hydrophilic and hydrophobic polymers to tailor the hydrogels to the specific needs of end-use applications. Current studies have focused on material elements common in extended wear contact lenses.

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.