Methods for preparing reinforced fluoropolymer composites comprising surface functionalized nanocrystalline cellulose

A method of preparing surface-only fluoro-functionalized nanocrystalline cellulose, the method comprising:

• reacting a surface of a nanocrystalline cellulose with a fluorinated electrophile under heterogeneous conditions to form the surface-only fluoro-functionalized nanocrystalline cellulose in which the outer circumference of the nanocrystalline cellulose is functionalized with fluorinated substrates, wherein the nanocrystalline cellulose comprises rod-like crystalline nanoparticles of cellulose having a crystalline structure, functionalization with fluorinated substrates does not decrease the size of the rod-like crystalline nanoparticles, and reacting the surface of the nanocrystalline cellulose with the fluorinated electrophile does not disrupt the crystalline structure of the nanocrystalline cellulose;
• purifying the surface-only fluoro-functionalized nanocrystalline cellulose by repeated centrifugation and redispersion;
• and
• isolating and drying the surface-only fluoro-functionalized nanocrystalline cellulose;
• wherein the rod-like crystalline nanoparticles have an aspect ratio (length:width) of from about 3 to about 500.