Copolyampholytes Produced from RAFT Polymerization of Protic Ionic Liquids

Abstract

Polyampholytic copolymers have been synthesized via reversible addition−fragmentation chain transfer (RAFT) polymerization of protic ionic liquid monomers. The monomers were prepared by acid−base proton exchange between acid and basic precursor conjugates, each containing one or more vinyl pendant groups. The polymerization, which was carried out without additional solvents present, led to high molecular weight glassy polymers, which were stable in the form of bulk viscous liquid ionic complexes. Various polyampholytes belonging to both linear and cross-linked families were prepared by judiciously varying the molecular structure of the acid precursor. Furthermore, by using solid-state NMR, the molecular arrangement of the polymeric backbone was identified, highlighting the presence of copolymers with both random and alternating copolymer chains which in the latter case involves a regularly alternating acid monomer, whereas the base occurs as a random sequence with the average and most probable number of monomers dictated by the stoichiometry used. The structural and mechanical properties of the resulting copolyampholytes were characterized by atomic force microscopy, peak-force quantitative nanomechanical analysis, differential scanning calorimetry, and small-angle X-ray scattering. These showed that the final polymers were essentially glassy and amorphous, with weak compositional fluctuations of the order of a few monomers and Young moduli in the range 1−3 GPa.

Synthetic and natural polyampholytes: Structural and behavioral similarity

“…The main advantage of swollen polyampholyte gel electrolytes over liquid electrolytes is that polymer electrolytes are intrinsically free of leakage‐related problems. Polyampholytic ionic liquids made of protic ionic liquid or zwitterionic monomers are another possibility for the development of ion‐conducting materials that retain proton conductivity without leaching ions or the requirement of a separate polymer matrix 11 …”

“…Betainic (or zwitterionic) polyampholytes are macromolecules containing identical numbers of acid‐base (or fully charged anionic‐cationic) species in the same monomer units 9 . Macromolecules formed via compensation of the cationic‐anionic monomer pairs without counterions are also zwitterionic polymers 10 or polyampholytic ionic liquids 11 . In the applicable literature, the terms amphoteric polyelectrolytes and amphoteric copolymers are also used.…”

Dynamics of Ion Locking in Doubly-Polymerized Ionic Liquids

“…This application relies on a significant restriction of ion transport upon polymerization, and builds on similar phenomena observed in the small number of other doubly-polymerizable and polyampholyte ionic liquid systems studied to date. [22][23][24][25] In 2002, Yoshizawa et al…”

Behaviors of quenched polyampholytes in solution and gel state

“…Linear and cross‐linked quenched polyampholytes (QPA) exhibit salt‐tolerant, 1 thermal‐resistant, 2 shear‐stable, 2 self‐healing, 3‐5 antifouling, 6,7 self‐assembling, 8‐11 and stimuli‐responsive, 12‐14 properties that provide broad impact as enhanced oil recovery (EOR), 15,16 and drag reduction agents, 17,18 structural biomaterials, 19 controlled delivery systems, 20,21 energy storage devices, 22 supercapacitors, 23 and actuators 24 . Synthetic protocol of QPA includes the conventional free‐radical copolymerization (FRP) of charged monomers, 1,25‐32 polymerization in microemulsion, 33‐39 polymerization of anionic‐cationic monomer pairs without counterions, 40 or zwitterionic monomers, 41 and reversible addition‐fragmentation chain transfer (RAFT) polymerization 7,14,42,43 . The QPA prepared in solution have a tendency to alternate between positively‐ and negatively‐charged monomers while prepared by means of a microemulsion polymerization allows to produce very high molecular weight copolymers (up to 1 × 10 7 g mol −1 ) that are more homogeneous in composition, with a reduced probability of continuous sequences of monomers of the same charge in the macromolecular chain.…”