Prof. M. W.
Matsen is Reader of Theoretical Polymer Physics at the University of
Reading. He joined the Department of Physics in 1996, following postdoctoral
positions in the Chemical Engineering Department at the University of
Minnesota and in the Physics Department at the University of Washington.
Since joining the Department here, he has established a research group
focusing on theory for structured polymers, some systems of which have direct
applications to nanotechnology. He has
recently moved to the Mathematics department.
Block
copolymers involve the bonding together of two or more incompatible polymer
chains, and are renowned for their self-assembly into nanoscale periodic
morphologies with wide-ranging symmetries. In recent years, thin layers of
block copolymer material have been used as templates for etching patterns
into various substrates. One intended application is to etch nanoscale
holes into silcon wafers in which ferromagnetic material is deposited to
form ultrahigh-density magnetic-storage devices. We are involved in the
theoretical modelling of such pattern formation and the prediction of its
symmetry in terms of the molecular characteristics of the block copolymer.
As an alternative to block copolymers, we are also
investigating the possible benefits of using binary polymeric brushes to
form patterned layers. In this case, two types of chemically incompatible
polymers are grafted to the substrate, and they self-assemble into patterned
morphologies. The mechanism is very similar to that of block copolymers,
but the immobility of the chains offers certain advantages.
Polyelectrolyte brushes, where chemically charged polymers are grafted to a
substrate in an aqueous environment, exhibit an interesting transition
between a collapsed and an extended state induced by changing the pH. This
transition offers a convenient mechanism of converting chemical energy into
mechanical energy to form various nanoscale machines. See
www.polymercentre.org.uk/expert/features/0101.php for a possible design
of a nanoscale pump.
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