Provided is a composition for forming a silica layer including a silicon-containing polymer, and a solvent, wherein the silicon-containing polymer has a weight average molecular weight (Mw) of 8,000 g/mol to 15,000 g/mol, and wherein a content of nitrogen atoms of the silicon-containing polymer measured by a kjeldahl titration method is 25 wt % to 30 wt % based on a total weight of the silicon-containing polymer.

A separator for a rechargeable lithium battery includes a porous substrate; and a coating layer on at least one surface of the porous substrate, wherein the coating layer is formed from a coating layer composition including an organosilazane compound, inorganic particles, an initiator, and a solvent, the coating layer includes a curable binder of the organosilazane compound and inorganic particles, the curable binder of the organosilazane compound includes a copolymer including a structural unit represented by Chemical Formula 1, a structural unit represented by Chemical Formula 2, and a structural unit represented by Chemical Formula 3, and a nitrogen (N) atom derived from Chemical Formula 1 is greater than about 0 at % and less than about 5 at % (atomic percent) in the coating layer, and a rechargeable lithium battery. Chemical Formula 1 to Chemical Formula 3 are as defined in the specification.

A separator for a rechargeable lithium battery includes a porous substrate; and a coating layer on at least one surface of the porous substrate, wherein the coating layer is formed from a coating layer composition including an organosilazane compound, inorganic particles, an initiator, and a solvent, the coating layer includes a curable binder of the organosilazane compound and inorganic particles, the curable binder of the organosilazane compound includes a copolymer including a structural unit represented by Chemical Formula 1, a structural unit represented by Chemical Formula 2, and a structural unit represented by Chemical Formula 3, and a nitrogen (N) atom derived from Chemical Formula 1 is greater than about 0 at % and less than about 5 at % (atomic percent) in the coating layer, and a rechargeable lithium battery. Chemical Formula 1 to Chemical Formula 3 are as defined in the specification.

A separator for a rechargeable lithium battery includes a porous substrate; and a coating layer on at least one surface of the porous substrate, wherein the coating layer is formed from a coating layer composition including an organosilazane compound, inorganic particles, an initiator, and a solvent, the coating layer includes a curable binder of the organosilazane compound and inorganic particles, the curable binder of the organosilazane compound includes a copolymer including a structural unit represented by Chemical Formula 1, a structural unit represented by Chemical Formula 2, and a structural unit represented by Chemical Formula 3, and a nitrogen (N) atom derived from Chemical Formula 1 is greater than about 0 at % and less than about 5 at % (atomic percent) in the coating layer, and a rechargeable lithium battery. Chemical Formula 1 to Chemical Formula 3 are as defined in the specification.

Provided herein is a method of coating a surface. A silicon-based coating composition is coated onto a surface. The silicon-based coating composition comprises polysilazane and polysilane comprising a formula (R.sub.1R.sub.2Si).sub.n, wherein n is greater than 1, and wherein R.sub.1 and R.sub.2 are the same or different and are chosen from alkyl, alkenyl, cycloalkyl, alkylamino, aryl, aralkyl, or alkylsilyl, which polysilane has a weight average molecular weight of more than 50,000. Also provided are silicon-based coating compositions and cured coatings from those compositions using the provided method.

Provided herein is a method of coating a surface. A silicon-based coating composition is coated onto a surface. The silicon-based coating composition comprises polysilazane and polysilane comprising a formula (R.sub.1R.sub.2Si).sub.n, wherein n is greater than 1, and wherein R.sub.1 and R.sub.2 are the same or different and are chosen from alkyl, alkenyl, cycloalkyl, alkylamino, aryl, aralkyl, or alkylsilyl, which polysilane has a weight average molecular weight of more than 50,000. Also provided are silicon-based coating compositions and cured coatings from those compositions using the provided method.

Provided herein is a method of coating a surface. A silicon-based coating composition is coated onto a surface. The silicon-based coating composition comprises polysilazane and polysilane comprising a formula (R.sub.1R.sub.2Si).sub.n, wherein n is greater than 1, and wherein R.sub.1 and R.sub.2 are the same or different and are chosen from alkyl, alkenyl, cycloalkyl, alkylamino, aryl, aralkyl, or alkylsilyl, which polysilane has a weight average molecular weight of more than 50,000. Also provided are silicon-based coating compositions and cured coatings from those compositions using the provided method.

Nanocomposite blends include metal oxide nanoparticles and at least two (meth)acrylic acid polymers where the nanoparticles are surface modified with a carboxylic acid silane and where the (meth)acrylic acid polymers are at least partially neutralized. The compositions are transparent, with high transmission and low haze up to very high nanoparticle loading. The compositions also exhibit improved mechanical properties of impact resistance and tensile modulus.

Nanocomposite blends include metal oxide nanoparticles and at least two (meth)acrylic acid polymers where the nanoparticles are surface modified with a carboxylic acid silane and where the (meth)acrylic acid polymers are at least partially neutralized. The compositions are transparent, with high transmission and low haze up to very high nanoparticle loading. The compositions also exhibit improved mechanical properties of impact resistance and tensile modulus.

Provided herein is a method of coating a surface. A silicon-based coating composition is coated onto a surface. The silicon-based coating composition comprises polysilazane and polysilane comprising a formula (R.sub.1R.sub.2Si).sub.n, wherein n is greater than 1, and wherein R.sub.1 and R.sub.2 are the same or different and are chosen from alkyl, alkenyl, cycloalkyl, alkylamino, aryl, aralkyl, or alkylsilyl, which polysilane has a weight average molecular weight of more than 50,000. Also provided are silicon-based coating compositions and cured coatings from those compositions using the provided method.