Crystallization-driven ordering and self-assembly in bottlebrush polymers

Abstract

The natural building blocks of linear polymer are monomers. Similarly, the natural building blocks of bottblebrush polymers are linear polymers (commonly referred to as polymacromonomers). It is well established that many properties of linear polymers can be tuned by using different copolymer systems. Similarly, we expect tunability of bottlebrush polymers by using chem. distinct polymer chains. A collaborative effort with Hadjichristidis from KAUST led us to a deeper study on the arrangement of chem. distinct polymeric units within the bottlebrush architecture. We have organized these samples into four categories based on the geometric connectivity: homo-bottlebrush polymer (H) in which all side chains have identical chem. functionality, main chain block bottlebrush polymers (M) which has chem. distinct side chains are grafted in groups along the backbone, random-co-bottlebrush (R) in which the sequence of grafting is detd. by the no. fraction of each chem. distinct side chain, and diblock side chains bottlebrush polymer (D) in which the side chains themselves are block copolymers. Three chem. distinct polymers were chosen as side chains to explore the effects of chem. functionality as well as the crystn. on behavioral properties: polyethylene (E), polycaprolactone (C), and atactic-polystyrene (S). The former two are known to be semicryst. In the melt phase we used differential scanning calorimeter (DSC) and in soln., we used small-angle neutron scattering (SANS). Our results indicate connectivity has a large impact on the behavior of bottlebrush polymers.