Fpinnovations

Stephanie Beck

Richard M Berry

Jean Bouchard

Joseph Donat Louis Godbout

Joseph Donat Godbout

Richard Berry

A new method to control the iridescence color of solid nanocrystalline cellulose (NCC) films by ultrasound and high-shear (mechanical) energy input to the NCC suspension prior to film formation is provided. As the energy input to the NCC suspension increases, the resulting film color shifts from the ultraviolet region towards the infrared region of the electromagnetic spectrum; this wavelength shift lies in the opposite direction to that caused by the addition of electrolytes to NCC suspensions prior to film formation. No additives are required to achieve the changes in color; color changes can also be effected by mixing two suspensions exposed to different levels of sonication.

Control of nanocrystalline cellulose film iridescence wavelength

A new method to control the dispersibility of dried nanocrystalline cellulose (NCC) by controlling solution pH and ionic strength is provided; when stable, non-reswellable acid-form NCC (H-NCC) films are placed in concentrated sodium hydroxide solutions, they swell but do not disperse; while sodium-form NCC (Na-NCC) or other NCC films having neutral monovalent counterions readily disperse in pure water, Na-NCC films placed in hydrochloric acid and sodium chloride as well as sodium hydroxide solutions of sufficient ionic strength swell, but do not disperse; similar properties are observed for freeze-dried NCC products. The dispersibility of these NCC films is a function of the ionic strength and the identity of the electrolyte solutions to which they are exposed. NCC films are envisaged that have barrier properties in an electrolyte solution but that disintegrate or disperse when rinsed with pure water at the end of their useful lifespan.

Method to control the dispersibility and barrier properties of dried nanocrystalline cellulose in solutions of different pH and ionic strength

Dried forms of nanocrystalline cellulose (NCC) with controllable redispersibility in water are provided; lightweight and easily transportable dried acid-form nanocrystalline cellulose which can be resuspended for use in a desired application can be produced by maintaining the humidity content of the NCC within a specific, low, range; evaporated acid-form NCC suspensions with moisture contents below this range are non-dispersible and therefore can be subsequently fixed in permanently dried form; the second form is produced by exchanging the proton of the acid-form NCC for neutral monovalent counterions and freeze-drying the NCC to give a solid product which rapidly disperses when placed in water; properties similar to those of the original suspension are also obtained with a brief sonication treatment.

Redispersible dried nanocrystalline cellulose

Dried nanocrystalline cellulose (NCC), in particular films of NCC, of controlled water dispersibility and a method to control the dispersibility of dried NCC by controlling electrolyte solution ionic strength and ion valency is described. Neutral M-NCC suspensions containing monovalent counterions (e.g., M=Na, K, NH, EtN) produced by neutralization of acid-form NCC (H-NCC) with the appropriate hydroxide, are readily dispersible in water when fully dried; this is in contrast to H-NCC. The dispersion of dried M-NCC in aqueous media is effectively prevented by a combination of (1) increased electrolyte concentration and ionic strength, and (2) higher valency of the cation component of the dissolved salt. Additionally, pre-treatment of dried M-NCC films with an electrolyte solution having a polyvalent cation, for example a divalent or trivalent cation is sufficient to prevent the subsequent dispersion of the M-NCC film in pure water.

Dried nanocrystalline cellulose of controllable dispersibility and method therefor

A new method to produce solid nanocrystalline cellulose (NCC) films containing patterns by differential heating of aqueous suspensions of NCC has been discovered. When acid-form NCC suspensions are dried by heating to temperatures above 50&#xb0; C., darkening of the NCC can occur, while neutral forms of NCC can produce iridescent chiral nematic films by heating to temperatures up to 105&#xb0; C. Placing materials of different thermal conductivity beneath the container containing an evaporating NCC suspension results in watermark-like patterns of different iridescent color imprinted within the film structure. Other colloidal rod-like particles can be employed in place of nanocrystalline cellulose (NCC), for example chitin or chitosan.

Growing community of inventors

Montreal, Canada

Stephanie Beck