Abstract:
The present invention relates to an easy, scalable method, relying on conventional and unconventional techniques, to incorporate tilt in the fabrication of synthetic polymer-based dry adhesives mimicking the gecko adhesive system. These dry, reversible adhesives demonstrate anisotropic adhesion properties, providing strong adhesion and friction forces when actuated in the gripping direction and an initial repulsive normal force and negligible friction when actuated in the releasing direction.
Abstract:
A dry adhesive includes a first plurality of fiber segments mechanically interlocked with a second plurality of fiber segments. A dry adhesive can include a first plurality of fibers mechanically interlocked with a second plurality of fibers or a single plurality of fibers having a first end region mechanically interlocked with a second end region. The fiber segments and fibers can be aligned, electrospun nanofibers. One or more continuous and scalable methods of making aligned fibers are also provided. One or more apparatuses are also provided.
Abstract:
Resilient members having near-surface architectures including microstructures for controlling friction are provided. A film-terminated array of fibrils having a sharp film/fibril juncture exhibits an unexpectedly large enhancement of adhesion, static friction and sliding friction. The enhancement is provided against rough indenters. A film-terminated array of elongated ridges and valleys unexpectedly exhibits low adhesion, and an unexpectedly large enhancement of sliding friction. The film-terminated ridge/valley design provides an anisotropic structure with direction-dependent frictional properties. The increase in sliding friction force varies as a function of interfibrillar spacing, and corresponds to a mode in which buckling of the terminal film occurs. The near surface architectures may be designed with varying scales and varying parameters to provide performance characteristics tailored to various applications. By way of example, the film-terminated ridge/valley array may be incorporated in motor vehicles tires to provide low rolling resistance and high sliding friction allow for high-performance braking during vehicle operation.
Abstract:
Provided herein are the polymers shown below. The value n is a positive integer. R1 is an organic group, and each R2 is H or a chemisorbed group, with at least one R2 being a chemisorbed group. The polymer may be a nanostructured film. Also provided herein is a method of: converting a di-p-xylylene paracyclophane dimer to a reactive vapor of monomers; depositing the reactive vapor onto a substrate held at an angle relative to the vapor flux to form nanostructured poly(p-xylylene) film; reacting the film with an agent to form hydrogen atoms that are reactive with a precursor of a chemisorbed group, if the film does not contain the hydrogen atoms; and reacting the hydrogen atoms with the precursor. Also provided herein is a device having a nanostructured poly(p-xylylene) film on a pivotable substrate. The film has directional hydrophobic or oleophobic properties and directional adhesive properties.
Abstract:
The invention provides unique releasable adhesive devices that are high-load bearing and highly stable while allowing adjustment of the weight-bearing angle in a wide range, thereby greatly expanding the scope of applications for technology. Adhesive systems and devices of the invention can be designed to fit applications ranging from household weight-bearing shelves and holders, components for transportation, athletic equipment, labels and advertising posts, automobile interior trims, permanent or reversible fasteners, as well as instruments and devices for industrial, commercial, medical or military applications.
Abstract:
Provided is an adhesive member whose adhesive force has relatively strong directional dependency. Specifically, provided is an adhesive member, which is configured to adhere to an adherend through an intersurface force, wherein when a strain energy release rate is defined as G1b and G2b and an adhesive energy is defined as Δγ1b and Δγ2b respectively, a horizontal section obtained by cutting the adhesive member parallel to an adhesive surface has an asymmetrized shape so that G1b/Δγ1b≠G2b/Δγ2b is satisfied.
Abstract:
Provided herein are the polymers shown below. The value n is a positive integer. R1 is an organic group, and each R2 is H or a chemisorbed group, with at least one R2 being a chemisorbed group. The polymer may be a nanostructured film. Also provided herein is a method of: converting a di-p-xylylene paracyclophane dimer to a reactive vapor of monomers; depositing the reactive vapor onto a substrate held at an angle relative to the vapor flux to form nanostructured poly(p-xylylene) film; reacting the film with an agent to form hydrogen atoms that are reactive with a precursor of a chemisorbed group, if the film does not contain the hydrogen atoms; and reacting the hydrogen atoms with the precursor. Also provided herein is a device having a nanostructured poly(p-xylylene) film on a pivotable substrate. The film has directional hydrophobic or oleophobic properties and directional adhesive properties.
Abstract:
The invention provides unique releasable adhesive devices and related methods that are capable of simultaneously adhering to two or multiple target surfaces of various nature and allow high load capacity, are reusable, easy release and suitable for extended and repeated use.
Abstract:
A one-way synthetic dry adhesive is provided that includes a dry adhesive material layer having an array of microwedges, where the dry adhesive layer is disposed on a substrate surface. The microwedges have a leading surface and a trailing surface, where the leading surface terminates into the trailing surface to form a wedge tip. The leading surface includes an angle up to 90 degrees with respect to the substrate surface, and the trailing edge surface includes an angle greater than the leading surface angle with respect to the substrate. The microwedges have a depth that is less than a thickness of the dry adhesive layer, and a series of siping features disposed in the dry adhesive layer, where a depth of the siping features is greater than the microwedge depth, and the series of siping features has a periodicity that is less than a periodicity of the array of microwedges.
Abstract:
A dry adhesive comprising a micro-featured and nano-featured surface, and a compliant surface having a hardness of about 60 Shore A or less, the micro-featured and nano-featured surface and the compliant surface being capable of forming upon contact a dry adhesive bond with each other.