W. Richard Bowen and Nidal Hilal 4
W. Richard Bowen and Nidal Hilal 4
W. Richard Bowen and Nidal Hilal 4
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10. FuTuRE PRosPECTs 277<br />
In recent years, a number of complementary measurement probes have<br />
been integrated onto AFM tips, permitting the imaging of other properties<br />
of a sample simultaneously with its topography. These novel developments<br />
have included the incorporation of electrochemical, thermal, magnetic <strong>and</strong><br />
electronic sensors. Researchers have also found that, in addition to being<br />
able to perform measurement functions, often these sensors allow the<br />
controlled alteration of the local environment around the tip. Preliminary<br />
work using certain types of sensors has shown that this feature could find<br />
great applicability in modulating micro- <strong>and</strong> nanoenvironments of living<br />
cells. Such functionalised probes could be incorporated into an existing<br />
AFM system, hence significantly enhancing its capability at modest cost.<br />
The availability of high-quality probes is also a factor limiting the uptake<br />
of some combined techniques, such as AFM <strong>and</strong> scanning near field optical<br />
microscopy (SNOM). The combination of super-resolution optical <strong>and</strong><br />
topographic imaging (AFM-SNOM) is certainly of great interest to biologists<br />
because of the wealth of new information it could provide.<br />
Polymers on surfaces play <strong>and</strong> will continue to play a major role in various<br />
engineering applications such as colloidal stabilisation, lab-on-a-chip<br />
devices, polymer composites <strong>and</strong> nanocomposites. Surprisingly, the significance<br />
of the polymer-solid interface region has been realised only relatively<br />
recently, <strong>and</strong> there are many gaps in our basic underst<strong>and</strong>ing. In nanocomposites,<br />
the interface regions can be so extensive that they can occupy most<br />
of the overall volume of the material even at low or moderate nanoparticle<br />
loadings. Furthermore, the conformation <strong>and</strong> nature of entanglements of<br />
confined polymer chains in close proximity to a solid surface can deviate<br />
significantly from the bulk. As AFM is a real-space, high-resolution surface<br />
technique capable of probing quantitatively both the nanostructural <strong>and</strong><br />
nanomechanical properties, it is likely to play an important role in the study<br />
of the interface region in polymer composites <strong>and</strong> nanocomposites.<br />
The self-assembly <strong>and</strong> self-organisation of polymers on solid–liquid<br />
interfaces can be used as a generic technique for the inexpensive mass<br />
production of surface nanostructures <strong>and</strong> nanopatterns. Many issues<br />
remain to be elucidated by careful quantitative experimentation, <strong>and</strong> AFM<br />
is being proven to be an indispensable tool for the study of such systems<br />
in air or in liquids. Furthermore, the recent development of high-speed<br />
AFM with image-acquisition times in the order of a few milliseconds is an<br />
important development that could allow the monitoring of the mobility<br />
of polymer chains on a solid surface <strong>and</strong> consequently the kinetic paths<br />
of the nanostructures/nanopatterns formation. AFM offers the possibility<br />
for systematic studies of such systems that can elucidate the underlying<br />
physical mechanisms of the processes occurring on solid surfaces. These<br />
studies can lead in the construction of phase/state diagrams, which may<br />
be used for the design of well-controlled <strong>and</strong> specified surface nanostructures<br />
for applications spanning from nanoelectronic devices to vectors for