Polymer particles excellent in uniform dispersibility and the use thereof are provided. The polymer particles contain a surfactant, and have a coefficient of variation in the volume-based particle diameter distribution in the range from not less than 13.0% to not more than 25.0%. When 15.0 g of water is added to 5.0 g of the polymer particles so as to disperse the polymer particles in the water by performing a dispersion treatment for 60 minutes using an ultrasonic cleaner, and furthermore when an obtained dispersion liquid is put into a centrifuge tube with an inside diameter of 24 mm so as to be centrifuged, by a centrifugal separator, under conditions that K factor is 6943 and a rotating time is 30 minutes to recover a supernatant, a concentration of non-volatile components in the obtained supernatant is less than 3.5 wt. %.

Various embodiments disclosed relate to pore inducers and porous abrasive forms made using the same. In various embodiments, the present invention provides a method of forming a porous abrasive form including heating an abrasive composition including pore inducers to form the porous abrasive form. During the heating the pore inducers in the porous abrasive form reduce in volume to form induced pores in the porous abrasive form.

Embodiments of the disclosure are generally directed to systems and methods for switchable electroactive devices for head-mounted displays (HMDs). In particular, a method may include (1) applying an electric field to an electroactive element of an electroactive device via electrodes of the electroactive device that are electrically coupled to the electroactive element to compress the electroactive element, which comprises a polymer material defining nanovoids, such that an average size of the nanovoids is decreased and a density of the nanovoids is increased in the electroactive element, wherein the electroactive device is positioned at a distance from a user's eye, and (2) emitting image light from an emissive device positioned such that at least a portion of the image light is incident on a surface of the electroactive device facing the user's eye.

An example device includes a nanovoided polymer element, which may be located at least in part between the electrodes. In some examples, the nanovoided polymer element may include anisotropic voids, including a gas, and separated from each other by polymer walls. The device may be an electroactive device, such as an actuator having a response time for a transition between actuation states. The gas may have a characteristic diffusion time (e.g., to diffuse half the mean wall thickness through the polymer walls) that is less than the response time. The nanovoids may be sufficiently small (e.g., below 1 micron in diameter or an analogous dimension), and/or the polymer walls may be sufficiently thin, such that the gas interchange between gas in the voids and gas absorbed by the polymer walls may occur faster than the response time, and in some examples, effectively instantaneously.

A polyurethane composition suitable for coating a surface of a substrate. The polyurethane composition can include an aliphatic polyester urethane matrix and a fluorinated ionic antistatic additive. The aliphatic polyester urethane matrix can comprise an aliphatic diisocyanate, a polyester polyol having a polyester diol and a polyester triol, and sulfonated polyester urethane polyol.

Example methods include depositing a precursor layer onto a substrate where the precursor layer includes droplets comprising a polymerizable material, inducing a phase inversion in the precursor layer to obtain a modified precursor layer including droplets of a non-polymerizable liquid within a polymerizable liquid mixture, and polymerizing the polymerizable liquid mixture to obtain a nanovoided polymer element. Examples include devices fabricated using nanovoided polymer elements fabricated using such methods, including electroactive devices such as actuators and sensors.

An optical element includes a nanovoided polymer layer having a first refractive index in an unactuated state and a second refractive index different than the first refractive index in an actuated state. Compression or expansion of the nanovoided polymer layer, for instance, can be used to reversibly control the size and shape of the nanovoids within the polymer layer and hence tune its refractive index over a range of values, e.g., during operation of the optical element. Various other apparatuses, systems, materials, and methods are also disclosed.

A holding material for a pollution control element which can sufficiently suppress scattering of inorganic fibers when the pollution control element is assembled in a casing, and which has a sufficiently high coefficient of friction. The holding material includes: a sheet-like main body made of first inorganic fibers having a minor axis in the range of from about 3 to 10 μm; and a surface layer which is provided on at least one surface of the main body and contains second inorganic fibers having a minor axis in the range of from about 1 to 15 nm.

A display device includes a scanned projector for projecting a beam of light, and a diffraction grating for dispersing the light at a plurality of angles into a waveguide, wherein at least a portion of the diffraction grating includes a nanovoided polymer. Manipulation of the nanovoid topology, such as through capacitive actuation, can be used to reversibly control the effective refractive index of the nanovoided polymer and hence the grating efficiency. The switchable grating can be used to control the amount of diffraction of an incident beam of light through the grating thereby decreasing optical loss. Various other methods, systems, apparatuses, and materials are also disclosed.

In some examples, a device includes a nanovoided polymer element, a planarization layer disposed on a surface of the nanovoided polymer element, a first electrode disposed on the planarization layer, and a second electrode. The nanovoided polymer element may be located at least in part between the first electrode and the second electrode. The planarization layer may be located between the nanovoided polymer element and the first electrode.