Elastomeric block copolymers are a versatile class of soft materials whose mechanical behavior can be tuned by adjusting their molecular architecture and intermolecular interactions. In this work, RAFT-derived ABA-type poly(n-butyl acrylate)- b -poly(n-vinylimidazole)- b -poly(n-butyl acrylate) triblock copolymers were employed to investigate how imidazolium-based ionic liquids (ILs) influence their structural and mechanical characteristics. The chain-extension step, initiated from a poly(n-butyl acrylate) macro-RAFT agent, enabled control incorporation of n-vinylimidazole (n-Vim), yielding triblock copolymers. The chain extension polymerization reactions is confirmed by 1 H NMR and GPC analysis. The molar mass (M n ) of the obtained triblock copolymers (poly(n-BA) 0.35 - b -poly(N-Vim) 0.30 - b -poly(n-BA) 0.35 ) (TBCP-2) and (poly(n-BA) 0.25 - b -poly(N-Vim) 0.50 - b -poly(n-BA) 0.25 ) (TBCP-1) increased from 21,040 Da (Molar mass of macro-RAFT agent) to 29,450 Da and 34,670 Da, respectively. A significant improvement in the elasticity and tensile strength of these triblock copolymers is noticed upon introduction of ionic liquids (ILs) and/or acid treatment. On comparing with poly(n-butyl acrylate) macro-RAFT agent, the glass transition temperature (T g ) of TBCP-2 and “TBCP-2 + IL-3” increased from -52°C to 36°C and 45°C, respectively. Introduction of ILs increases the ionic interactions in the triblock copolymers, that restricting the chain mobility and increases its T g value. Upon acid treatment, a substantial increase in the hydrodynamic radius of “TBCP-2 + IL” is notice, which suggest a strong ion-dipole association and electrostatic interactions between IL and the functional group of the acidified triblock copolymers, which holding the ILs and polymer chains together. The influence of IL incorporation in n-vinylimidazolium containing triblock copolymers on their chain packing, microstructural organization and the elastomeric behaviour is explored, and reported here. RAFT derived, ABA-type poly(n-butylacrelate)- b -poly(N-vinylimidazole)- b -poly(n- butylacrelate) triblock copolymer, upon mixing with ionic liquid and acid treatment, exhibits enhanced thermal and mechanical performance. The electrostatic interaction between IL additive and the imidazole ring of the triblock promotes coil expansion, increases the T g , and significantly improves elastomeric behaviour.
Haribabu et al. (Sun,) studied this question.