Manipulation of Molecular Weight Distribution Shape as a New Strategy to Control Processing Parameters

Molecular weight and dispersity (Ð) influence physical and rheological properties of polymers, which are of significant importance in polymer processing technologies. However, these parameters provide only partial information about the precise composition of polymers, which is reflected by the shape and symmetry of molecular weight distribution (MWD). In this work, the effect of MWD symmetry on thermal and rheological properties of polymers with identical molecular weights and Ð is demonstrated. Remarkably, when the MWD is skewed to higher molecular weight, a higher glass transition temperature (Tg), increased stiffness, increased thermal stability, and higher apparent viscosities are observed. These observed differences are attributed to the chain length composition of the polymers, easily controlled by the synthetic strategy. This work demonstrates a versatile approach to engineer the properties of polymers using controlled synthesis to skew the shape of MWD. Shaping the symmetry of molecular weight distribution by utilization of a facile synthetic technique is demonstrated as a powerful strategy to engineer rheological properties, and therefore to tune the processing parameters of polymers. This is an efficient approach to process polymers at milder conditions without alternating their chemical properties.