Poly(methyl methacrylate) (Perspex®)

Poly(methylmethacrylate) is a commodity polymer which forms the basis of the Perspex®, Plexiglass® and Lucite® families of materials. These have a wide range of applications many of which exploit the polymer's high optical clarity. The softening temperature (Tg) is technologically one of the most important properties of the material and this is strongly influenced by the tacticity of the polymer, i.e. the placements of the ester and methyl groups along the polymer backbone. For example, free radical-generated material is biased towards the syndiotactic form (ca. 67%) affording a Tg of ca. 105°C. However, as the syndiotacticity is increased, the Tg also rises (to ca. 135°C for highly syndiotactic material), and this holds clear advantages for applications where the polymer is exposed to higher temperature environments.

In recent years we have introduced a number of new catalysts or initiator systems for the controlled polymerisation of methyl methacrylate. These include highly active catalysts based on Group 4 metallocenes and an aluminium system supported by salen ligands.

Examples of catalyst or initiator systems for the controlled polymerisation of methyl methacrylate.

In the case of aluminium, the difficulty associated with introducing the enolate moiety led us to develop a novel nickel-catalysed approach to the formation of the active site. In more recent studies we have found that well-defined magnesium enolate species can be used to polymerise MMA to > 90% syndiotactic polymer, at temperatures > -30°C, and in a living manner.

Representative publications:

 
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