Professor Peter Mallon - Research

Complex polymer materials and polymer nanocomposites

Research in our group can be broadly characterised as investigations of the structure property-relationship in complex polymer materials including semi-crystalline polymers, multiphase copolymers, nano-structured polymers and nano-filled polymer composite. We are interested in the synthesis of these materials as well as in the development of novel analytical approaches and techniques to characterise these materials.  We investigate the properties and potential application of these materials in for example, producing nanofibre composites and conductive polymer composites.

Recently, work in our group has focused on organic-inorganic hybrid materials, the electrospinning of amphiphillic graft copolymers and polymer nanofibres with carbon nanomaterials. This has included the synthesis, preparation, properties and applications of these materials. Of particular interest is the electrospinning of multiphase amphiphillic copolymers in the presence of carbon nanomaterials and the resultant external and internal fibre morphology.

Some examples of our recent work are given below.

The figure above shows porous electrospun fibres containing multi-walled carbon nanotubes (MWCNT). These fibres are electrospun using a poly(acrylonitrile- graft-poly(dimethlysiloxane)) (PAN-g-PDMS) amphiphillic copolymer. The rapid crystallisation of the PAN segments as well as the molecular alignment of the electrospinning process results in a “freezing-in” of the self- assembled structure of the polymer in the electrospinning solution.  (GM Bayley and PE Mallon, Polymer 53 (2012) 5523-5539).

The example in the figure shows superhydrophobic surfaces produced by electrospinning amphiphillic poly((methyl methacrylate) –graft- poly(polydimethylsiloxane)) copolymers. The superhydrophobic surface is produced by the combination of the surface texture on both the micro and nanoscales (similar to the so called “lotus-effect”) combined with the preferential surface segregation of the hydrophobic PDMS segments in the polymer nanofibres. (M Swart and PE Mallon, Pure and Applied Chemistry 81(3) 495 (2009)).

(GM Bayley, M Hedenqvist and PE Mallon  Polymer 52 4061 (2011))

The example above shows the potential application of electrospun amphiphillic graft copolymers in the presence of carbon nanotubes. The elastomer nanocomposites are produces by adding the polymer nanofibres composites to a silicon matrix. This leads to a very large increase in the strain at break in the materials. This is somewhat unusual in polymer nanocomposites as the presence of nanofillers typically dramatically increase the modulus (hardness) of the materials, but most often results in a large decrease in the strain at break.  (GM Bayley, M Hedenqvist and PE Mallon, Polymer 52 4061 (2011)).

Current group members

K Sharlach ( MSc)

F Meltz (MSc)

N Basson (MSc)

H Etmimi (Post-doctoral fellow)

Previous group members

TA Berhane (MSc 2004 – Degradation and recovery of poly(dimetlysiloxane) (PDMS) based composites.)

AJ Rabie (MSc 2004 - Blends with low-density polyethylene (LDPE) and plastomers. Promoter: PE Mallon Co-promoter: AJ van Reenen)

M Sweed (MSc 2006 - Co-crystallization in polyolefin blends studied by various crystallization analysis techniques.)

W Elhari (MSc 2006 - Synthesis and characterization of comb-polymers with controlled structure.)

AAM Baleg (MSc 2006 – Synthesis and characterization of graft and block copolymers using hydroboration. Promoter: PE Mallon Co-promoter Dr APJ van Zyl)

GM Bayley (MSc 2007 - Synthesis and characterisation of organic-inorganic hybrid block copolymers of poly(dimethylsiloxane) and polystyrene.)

M Swart (MSc 2007 - Synthesis and characterization of electrospun organic-inorganic hybrid graft copolymer nanofibres of poly(methyl methacrylate) and poly(dimethylsiloxane).)

G Krugel (MSc 2007 - Synthesis and characterisation of hybrid graft copolymers of poly(dimethylsiloxane) and poly(methyl methacrylate).)

M Elbuzedi (MSc 2007 Material study and properties of polymers used in composite high voltage insulators.)

E De Goede  (PhD 2008 - The development of analytical techniques for studying degradation in impact polypropylene copolymers. Promoter: Prof Pasch, Co-promoter PE Mallon)

ABE Abduallah (PhD 2009 - Microscopic surface and bulk morphology of semicrystalline poly(dimethylsiloxane)-polyester copolymers.)

AC Sutherland (MSc 2009 - Organic-inorganic hybrid graft copolymers of polystyrene and polydimethylsiloxane.)

J Simpson (MSc  2010 -  Synthesis and characterization of unsaturated polyesters for use in multi-vesiculated particles (MVPs).)

M Sweed (PhD 2011 - Free volume properties of semi-crystalline polymers.)

G Bayley (PhD 2011 - Novel electrospun fibres of amphiphilic organic-inorganic graft copolymers of poly(acrylonitrile)-graft-poly(dimethylsiloxane) for silicone composite reinforcement.)

W Elhrari (PhD 2011 - Synthesis and characterization of multiphase copolymers)

M Malan (MSc 2012 – Novel materials for VOC analysis. Promotor Porf PE Mallon, co-promoter Dr A De Villiers)

H Etmimi (PhD 2012 - New approaches to the synthesis and exfoliation of polymer/functional graphene nanocomposites by miniemulsion polymerization. Promoter RD Sanderson, Co-promoter PE Mallon)

Other:

L Klumperman (DSc 2012 - NMR studies of radical polymerisation processes.)