Research Publications People Computers

Gavin Buxton


The above figures display the morphology and elastic strain field corresponding to a filled diblock copolymer. First, the B polymer domain is shown as a blue isosurface and red isocaps along with the nanoparticles which is shown as black spheres. The black spheres are clearly localised in the transparent A polymer domains. The second figure, shows the elastic strain field when the solid filled diblock copolymer has been loaded in the x-direction. The filler nanoparticles (indicated by the dark regions of low strain) significantly reinforce the surrounding polymer. Furthermore, by localizing the nanoparticles within one domain of the bicontinuous diblock copolymer structure the particles percolate to form a continuous backbone of reinforcing material which spans the length of the system and results in a much stiffer composite.

For more details see:
G.A.Buxton and A.C.Balazs. 'Simulating the Morphology and Mechanical Properties of Filled Diblock Copolymers', Phys. Rev. E 67(3) 031802 (2003).

Here we show how embedding nanoscale rods into a phase separating binary polymer blend can result in novel supramolecular structures and how these structures can significantly enhance the conductivity of the polymer. Conducting nanorods are important additives to polymers, especially in the design of flexible solar panels. First, we show the structure of these networks. The nanorods are corralled into the minority polymer domains and in turn stretch the polymer droplets into a continuous network. Second, through the simulation of the eletrical current propagating in these systems we can see regions of high current density flow through these rods. By coralling the nanorods into percolating supramolecular networks the conductivity of the reinforced system is significantly increased.

For more details see:
G.A.Buxton and A.C.Balazs. 'Predicting the Mechanical and Electrical properties of Nanocomposites Formed from Polymer Blends and Nanorods', Molecular Simulations, 30 249-257 (2004)

Most polymers are processed under shear and therefore, the domain structures of polymer blends become highly anisotropic. This anisotropy transfers through to the mechanical properties. Here, we show the highly anisotropic domain structure for a binary polymer blend processed under shear. Also, we can simulate the dynamic propagation of a crack through this system (see picture). We assume that the interface is weak and investigate the anisotrpic properties of the system. We find that the strength, toughness, frcature toughness and critical J-integral all show highly anisotropic behaviour.

For more details see:
G.A.Buxton and A.C.Balazs. 'Modelling the Dynamic Fracture of Polymer Blends Processed Under Shear', Phys. Rev. B 69(5) 054101 (2004)

Recently, we have investigated the use of computationally efficient models in the simulation of cardiac mechanics. The above animation shows the propagation of a wave of electrical excitation and the resultant muscle contraction in a simplified heart model. First the SA node is activated leading to the upper region being excited, which in turn leads to the contraction of both the artrias. Next the electrical excitation spreads via the AV node and down the bundle of His. This leads to the rapid contraction of both the ventricles, ejecting blood out through the aorta and pulmonary artery.

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