A process for producing cationic colloidal silica which is surface-modified by at least one aminoalkoxysilane having an amino group in cationic form, comprises: (i) under alkaline conditions, reacting a negatively charged colloidal silica with at least one aminoalkoxysilane having an amino group in cationic form at above 20 C. to produce a surface-modified colloidal silica with a net negative surface charge; and (ii) reversing the surface charge of the net negatively charged surface-modified colloidal silica by contacting the net negatively charged surface-modified colloidal silica with an ion exchange resin to obtain a positively charged surface-modified colloidal silica.

The present application discloses an eco-friendly long-lasting heat-sensitive paper, including a substrate layer, a base color layer, a heat-sensitive covering layer, and a protective layer that are arranged sequentially from bottom to top, where the heat-sensitive covering layer is prepared as follows: coating a heat-sensitive covering layer raw material on the base color layer, and oven-drying a resulting product, where the heat-sensitive covering layer raw material is an emulsion obtained by mixing an acrylic hollow microsphere with a host resin. In the present application, an acrylic hollow microsphere that can change from an opaque state to a transparent state after rupturing under heat is used as a heat-sensitive covering layer to cover a base color layer to obtain the heat-sensitive paper with heat-sensitive color development characteristics.

The present disclosure provides curable compositions comprising polymerization inhibitor-functionalized particles to prevent undesired polymerization of the polymerizable compounds in the curable compositions during their transportation, handling or storage, or during 3D printing processes. Such curable compositions can be used to produce polymeric materials with properties suitable for use in various 3D printed objects, such as orthodontic appliances.

A cristobalite includes: a d50 particle size selected within a range of from 1 m to 15 m; an L color coordinate of greater than 96; a color coordinate of less than 1; and a b color coordinate of 1 or less, in which the cristobalite is a powder. Also provided are compositions containing the cristobalite, coatings formed with compositions, and methods of preparing cristobalite.

Silica nanoparticles grafted with hydrophobic branches and amines may be used to mitigate corrosion. For example, method for mitigating corrosion downhole may include introducing a treatment fluid into a subterranean formation, wherein the treatment fluid includes: an aqueous acid and a plurality of silica nanoparticles grafted with hydrophobic branches and amines. Examples of amines may include C2 to C18 amines. Examples of hydrophobic branches may include C2 to C18 alkyl groups.