Improving the performance of pressure sensitive adhesives by tuning the crosslinking density and locations

The inter-chain sliding is the dominant mechanism of energy dissipation within pressure sensitive adhesives (PSAs), and it is significantly affected by the density and location of crosslinks on the polymer chains. The work presents molecular dynamics simulations of the debonding process of PSAs using a coarse-grained model. Introducing crosslinks enhances the connectivity of the polymer network, so that more chains participate in the inter-chain sliding. However, too many crosslinks have a deleterious effect on the adhesive performance, reducing the extent to which the polymer chains can be stretched. This limitation is alleviated by placing the crosslinking sites on the far ends of the polymer chains, so that the whole length of the polymer chains can slide. Our model enables a predictive theoretical framework for better understanding the performance of PSAs at the molecular scale and helps to propose strategies for the de novo bottom-up design of high-performance PSAs.