Functionalized Elastomeric Ionomers Used as Effective Toughening Agents for Poly(lactic acid): Enhancement in Interfacial Adhesion and Mechanical Performance

Abstract

A series of elastomeric ionomers functionalized with different imidazolium-based cations were synthesized by a facile and efficient quaternization reaction from commercial bromobutyl rubber (BIIR) and different functionalized imidazoles, including 1-ethylimidazole, N-(2-hydroxyethyl)­imidazole, newly designed 1-(11′-hydroxyundecyl)­imidazole, and N-[3-(1H-imidazol-1-yl)­propyl]-hexanamide. These BIIR-based elastomeric ionomers (i-BIIRs) with a balanced mechanical performance, interfacial polar interactions, and a suitable processability were employed as novel modifying agents for poly­(lactic acid) (PLA) to achieve highly toughened sustainable blends. The influence of the cationic structure of these ionomers and blend ratio on the compatibility and mechanical performance of the blends was thoroughly investigated. The introduction of polar hydroxyl groups with varied alkyl lengths or an amide group into the imidazolium cation of the i-BIIRs markedly improved the compatibility and impact toughness of the PLA/i-BIIR blends, relative to those of the pure BIIR and the i-BIIR ionomers without functional polar groups. These PLA/i-BIIR ionomer blends exhibited an excellent flexibility–stiffness balance, in which the highest elongation at break up to 300% was achieved with a small loss in stiffness. An impressively high impact strength of 17.1 kJ/m2 was achieved for the PLA and i-BIIR-11-OH (80/20) blends, and this impact strength is almost 6 times that of the neat PLA. The interfacial adhesion between the evenly dispersed small ionomer and PLA matrix was improved because the synergistic multiple intermolecular interaction is the native mechanism for enhancing the toughness and flexibility of the blends.

Novel Designed PEG‐Dicationic Imidazolium‐Based Ionic Liquids as Effective Plasticizers for Sustainable Polylactide

“…Recently, ILs and the polymer containing ionic groups were reported by us and other groups as compatibilizers or toughening agents for biobased polymer blends. [ 27‐29 ] The good compatibility between IL groups with the polymer phases offered us impressive physical performances, demonstrating that the ILs have high potential for developing high‐performance biobased polymer materials.…”

Research progress on toughening and modification of polylactic acid with environmentally friendly materials

“…强度却大幅下降, 且由于增塑剂小分子易从本体向表 面迁移, 这会使产品在储存或使用过程中变脆及失去 透明性 [10] . Wang等 [11] 图 1 熔融共混过程中PLA、PBS和EGMA之间可能发生的 原位反应 [16] (网络版彩图) 图 4 咪唑类溴丁基橡胶离聚物的结构及其合成路线 [25] (网 络版彩图) Figure 4 Structure and synthesis route of imidazole bromobutyl rubber ionomer [25] (color online).…”

Ultra-Tough Polylactide/Bromobutyl Rubber-Based Ionomer Blends via Reactive Blending Strategy

“…Recently, we developed a series of ionomers containing organic ionic groups as modifiers for PLA to effectively improve the performance of PLA ( Chen et al, 2018 ; Huang et al, 2020 ; Li et al, 2020 ; Sun et al, 2020 ). The imidazolium ion group has excellent structural designability, endowing the ionomers with plentiful functionalities and good performance.…”

“…More importantly, these functional groups from the imidazolium group will also provide active sites for the next reaction modification. On this basis, we synthesized a series of imidazole-based poly(isobutylene-co-isoprene) ionomers ( i -BIIRs) for the toughening modification of PLA ( Huang et al, 2020 ).…”