4 the state of science in south africa
C H E M I S T R Y
grammes is to produce materials that will the first to show experimentally that there
have a porous metal-organic framework is a transition in kinetic behaviour if the
structure. concentration of deactivator is increased.
In the programme focusing on advanced
The second DST/NRF national research chair macromolecular architectures, the group
in physical chemistry is that of Bert Klump- is involved in the design, the synthesis and
erman at the University of Stellenbosch, the characterisation of complex macromo-
working on advanced macromolecular ar- lecular structures, with the main emphasis
chitectures. Living radical polymerisation being on molecular brushes and polymer-
(LRP) is used by the group as the central protein conjugates. Densely grafted alter-
technique in the synthesis of advanced nating copolymers are among the target
macromolecular architectures. Self-assem- structures. Next to the chemical characteri-
bly of these architectures and heterogene- sation of the structures, an increasing focus
ous polymerisation processes are used to will be on their solution properties. From a
create ordered structures on a larger length synthetic point of view, the emphasis is on
scale. In order to optimise the degree of con- living radical polymerisation techniques but
trol in LRP processes, mechanistic studies complementary techniques are used when
are conducted to increase the understand- required. Over the last two years, the ma-
ing of the fundamental processes involved. jority of new research projects in the group
The field in which the group’s research has have had a biomedical focus such as drug
had the largest impact in the past ten years delivery, anti-microbial fibres, immobilisa-
is the kinetics and mechanisms of revers- tion/conjugation of proteins and enzymes,
ible addition-fragmentation chain transfer and a sampling device for TB diagnostics.
(RAFT) mediated polymerisation. The group
has led the way to a deeper understanding Research in heterogeneous catalysis is
of the initial stages of the RAFT process, as carried out at a number of departments
well as in studies into the later stages of this of chemistry in the country as part of the
process. A selective initialisation process DST/NRF Centre of Excellence in Catalysis
was discovered in which the original RAFT- mentioned above. Not surprisingly, the
agent is converted into its single monomer emphasis is on reactions which form part
adduct. The work is being expanded in vari- of the Fischer-Tropsch regime and the de-
ous directions. Use will be made of nitrox- velopment of potential gold and platinum
ide-mediated polymerisation in order to metal catalysts. Programmes of one particu-
determine relevant kinetic constants. An- lar sub-centre include the catalytic action of
other related field of research in which the nanogold, direct conversion and catalytic
group has made very significant contribu- decomposition of methane, methanol-me-
tions is mechanistic and kinetic studies of diated routes for gas-to-liquid and related
atom transfer radical polymerisation (ATRP). reactions, zeolites and acid catalysis and
A number of contributions have placed the catalytic properties of nanometal-polymer
group among the world leaders in kinetic composites. The emphasis in the former
and mechanistic studies of ATRP. They were programme is on understanding the be-
118
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