Flame retardant modified cellulosic nanomaterials (FR-CNs) prepared using phosphorus-containing monomers

A method of making a flame retardant modified cellulosic nanomaterial, the method comprising:

• reacting a halogenated phosphorus-containing monomer and hydroxyl groups on the surface of a cellulosic nanomaterial to functionalize a surface of the cellulosic nanomaterial to incorporate a phosphorus-containing moiety, wherein the cellulosic nanomaterial is selected from a group consisting of cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and combinations thereof, and wherein the halogenated phosphorus-containing monomer is selected from a group consisting of diphenyl phosphoryl chloride, diphenylphosphinic chloride, and combinations thereof;
• reacting a compatibilizing monomer and remaining hydroxyl groups on the surface of the cellulosic nanomaterial that remain after reacting the halogenated phosphorus-containing monomer and hydroxyl groups on the surface of the cellulosic nanomaterial to further functionalize the surface of the cellulosic nanomaterial to incorporate an orthogonal functionality selected to enhance the compatibility of the flame retardant modified cellulosic nanomaterial with a polymer into which the flame retardant modified cellulosic nanomaterial is to be blended, wherein the compatibilizing monomer is selected from a group consisting of epichlorohydrin, methacryloyl chloride, acryloyl chloride, and combinations thereof, and wherein the orthogonal functionality is separately appended to the surface of the cellulosic nanomaterial relative to the phosphorus-containing moiety.

A process of making a composite material, the process comprising:

• blending a flame retardant modified cellulosic nanomaterial into a polymer, wherein the flame retardant modified cellulosic nanomaterial is made by a method comprising:
• reacting a halogenated phosphorus-containing monomer and hydroxyl groups on the surface of a cellulosic nanomaterial to functionalize a surface of the cellulosic nanomaterial to incorporate a phosphorus-containing moiety, wherein the cellulosic nanomaterial is selected from a group consisting of cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and combinations thereof, and wherein the halogenated phosphorus-containing monomer is selected from a group consisting of diphenyl phosphoryl chloride, diphenylphosphinic chloride, and combinations thereof;
• reacting a compatibilizing monomer and remaining hydroxyl groups on the surface of the cellulosic nanomaterial that remain after reacting the halogenated phosphorus-containing monomer and hydroxyl groups on the surface of the cellulosic nanomaterial to further functionalize the surface of the cellulosic nanomaterial to incorporate an orthogonal functionality selected to enhance the compatibility of the flame retardant modified cellulosic nanomaterial with the polymer, wherein the compatibilizing monomer is selected from a group consisting of epichlorohydrin, methacryloyl chloride, acryloyl chloride, and combinations thereof, and wherein the orthogonal functionality is separately appended to the surface of the cellulosic nanomaterial relative to the phosphorus-containing moiety.