Efficient sampling of functionalized polymers forming reversible linkages

We investigate single-chain folding of polymers functionalized with reactive complexes by means of a new Monte Carlo algorithm. Reversible linkages, mediated by non-covalent (e.g. hydrogen bonding or π-π stacking) or... [ view full abstract ]

We investigate single-chain folding of polymers functionalized with reactive complexes by means of a new Monte Carlo algorithm. Reversible linkages, mediated by non-covalent (e.g. hydrogen bonding or π-π stacking) or dynamic covalent interactions, are used to design single-chain nanoparticles with structural and responsive properties controlled by the number of reactive complexes and the magnitude of their interactions. 

Functionalized polymers are modelled as self-avoiding chains with randomly distributed reactive sites that can cross-link reversibly. We proposed an efficient and general method in which rearrangements of open and cross-linked structures are attempted in a single Monte Carlo move. Reversible linkages within a polymer chain are sampled by configurational bias regrowth of sub-polymer units containing reactive complexes. We explore the effect of binding strength, complex size (number of reaction units in each reactive complex), and directionality of the chemical bond as design parameters on chain properties such as radius of gyration and asphericity. Furthermore, the method allows calculation of the free energy landscape as a function of the number of bound complexes revealing the limits of structural transitions in functionalized polymers. The proposed methodology is extendable to other supramolecular systems like reversible nanogels or chromatin organisation.