Order–disorder transition in supramolecular polymer combs/brushes with polymeric side chains

Abstract

Supramolecular polymer combs/brushes can be used as smart materials which incorporate the properties of linear polymers with branch polymers depending on the temperature, grafting density, branch molecular weight and most importantly type of non-covalent interaction between the main chain and side chains. Three sets of polymers were synthesized and mixed based on a specific interaction between the main chain and the side chain polymers. The first two sets based on the combination of 2,4-diamino-1,3,5-triazine (DAT) : thymine (THY) and 2-ureido-4[1H]-pyrimidinone (UPy) : (1-(6-isocyanatohexyl)-3-(7-oxo-7,8-dihydro-1,8-naphthyridin-2-yl)urea) (ODIN) were a blend and the third one using ODIN : ODIN interactions was used without a main chain. The polymer set using ODIN : ODIN interaction showed long-range ordering due to strong ODIN aggregation, whereas UPy : ODIN-based polymer combs showed comb-like clusters without any ordering. The phase separation in the THY : DAT system was more pronounced and was further improved after the addition of more equivalents of side chains. Moreover, using melt rheology, consistent with the SAXS data, it was concluded that long-range ordering is responsible for the elastic properties and the flow temperature (T_flow) is lower than the order–disorder transition temperature (T_ODT). This work can be considered as a toolkit for the design of bottlebrush and comb polymers as well as supersoft elastomers and stimuli-responsive materials.