It described the surface roughness of nanocellulose film prepared via spray coating.

1. Engineering the smoothness of nanocellulose (NC) films via spray coating
Abstract
Novel nanocellulose (NC) films of controlled smoothness are produced via spraying
NC suspensions onto steel surfaces and drying under standard conditions. The films were
characterized and analysed by surfaceconfocal laser profilometry. The smoothness of the NC
films is controlled by the smoothness of the receiving steel surface. Tailoring of the NC film
properties namely basis weight, thickness and strength, is achieved simply by adjusting
suspension consistency and the process variable of the spraying process. The spray coated
NC film has two different surfaces with the surface in contact with the metal notably smoother
than the air side which is the rough side. Here, we investigate the parameters controlling the
surface smoothness of the NC film. The effect of suspension consistency (1.25 to 2.00 wt. %
NC), homogenization of fibres ( 0 to 2 pass), carboxy methyl cellulose (CMC) addition on NC
film smoothness was quantified, using a series of model receiving plates ranging in
smoothness.. The NC film surface smoothness was correlated to NC fibrils diameter and
receiving surface roughness. NC fibril diameter is the parameter controlling film smoothness,
which can be controlled by more than an order of magnitude. These nanocellulose films are
of interest as solar panels, supercapacitors, photonics etc., which require very smooth
substrates. Spraying NC suspensions onto polished receiving surfaces is a rapid single step
process to produce thin nanocellulose films of tailored smoothness.