Natural
cellulose molecules have a strong tendency of being aggregated into larger
structures. Thus the imaging of isolated individual cellulose molecules is hampered
for a long time. In the present work, we manage to observe, for the first time,
the isolated individual natural cellulose chains on a sample surface by means
of AFM. The advantage of the ionic liquid, in which natural cellulose can be
molecularly dispersed, is considered to be the key point for the successful
imaging. Moreover, we find that the surface charge can influence the morphology
of the single cellulose chains upon adsorption. That is, on the positively
charged surface, individual cellulose chains adopt an extended conformation; while
on the negatively charged surface, a compact globule conformation is observed.
