Nanopaper is a cutting edge variety of paper with a strength of 214 megapascals (MPa), greater than 130 MPa of cast iron and approaching that of structural steel (250 MPa). Typical paper has a strength of 1 MPa.
The nanopaper, developed by scientists at the Royal Institute of Technology in Stockholm, Sweden and announced via press releases in early June 2008, gets its strength from trillions of tiny linked cellulose nanofibers. The cellulose fibers in nanopaper were produced by making a sludge of cellulose, similar to the way normal paper is made, but then further breaking it down using enzymes, mechanical grinding, and chemical treatment with carboxymethanol. The result are fibers 1000 times smaller than the fibers in typical paper.
These fibers link together in a defect-free matrix, in contrast to the fibers in traditional paper, which are so large you can see them with a magnifying glass. This nanopaper beat the prior record of 103 MPa for a high-strength paper. The first strength tests used strips 40 mm long by 5 mm wide and about 50 microns thick.
The researchers that developed the nanopaper touted its numerous advantages in the publicity surrounding its announcement. They foresee nanopaper being used to replace all grocery bags, providing an eco-friendly alternative to petroleum-consuming plastic bags. Nanopaper could be used as a reinforcing agent in plastics in lieu of highly expensive carbon fibers. Nanopaper is riddled with large pores, allowing faster drying, which would decreases the price of any final product that uses it.
The raw material of nanopaper — cellulose — is the most abundant organic polymer on the planet. This means that nanopaper products could be substantially cheaper and more useful than products based on more exotic and expensive-to-produce nanomaterials such as carbon nanotubes. Nanopaper might even find use as a general-purpose construction material, as long as mass-production fabrication costs will be as low as the inventors claim.
Two other materials are less frequently referred to as nanopaper. These include a titanium oxide nanofiber matrix created by chemists at the University of Arkansas, which could be used as a fire-retardant covering or pathogenic filter, and a potassium manganese oxide nanowire matrix created by MIT researchers as a sponge to suck up oil spills.