Conductive Polymer Protonated Nanocellulose Aerogels for Tunable and Linearly Responsive Strain Sensors.

Strong and highly conductive aerogels have been assembled from cellulose nanofibrils (CNFs) protonated with conductive poly(3,4-ethylene dioxythiophene)/poly(styrene sulfonate) (PEDOT/PSS) complex at equal mass or less. Protonating CNF surface carboxylates and hydrogen-bonding CNF surface carboxyls with PSS in PEDOT/PSS generated PEDOT/PSS/CNF aerogels that were up to ten times stronger while as conductive as neat PEDOT/PSS aerogel, attributed to the transformation of PEDOT benzoid structure to the more electron transfer-preferred quinoid structure. Ethylene glycol vapor annealing further increased the conductivity of PEDOT/PSS/CNF aerogels by 2 orders of magnitude. The poly(dimethylsiloxane) (PDMS)-infused conductive PEDOT/PSS/CNF aerogel (70 wt % CNF) transform a resistance-insensitive PDMS-infused PEDOT/PSS aerogel (gauge factor of 1.1 × 10-4) into a stretchable, sensitive, and linearly responsive strain sensor (gauge factor of 14.8 at 95% strain).