The effect of the CNC surface chemistry on CNC dispersion was
directly observed by AFM studies. AFM unambiguously showed
that that modified CNC dispersion within the PLA matrix was
highest (lowest aggregation) for lactic acid modified CNCs. Under
the Fischer esterification conditions lactic acid can undergo esterification
with itself and thus modifying CNCs with lactic acid gave
the ability to produce lactate oligomers from the surface of CNCs.
The results herein show conclusively that surface modification of
CNCs is critically important in engineering CNC-polymer nanocomposites
with optimal performance properties. It is also noted
herein that, in addition to lactate monomer esters, lactate oligomers
may also have formed and be esterified to CNCs. Further work
will be needed to determine the extent that this occurs and how it
alters LA-CNC/PLA matrix properties. Furthermore, future work will
address variation of lactate substitution on CNC fibers