Functional Ionic Liquid-based Responsive Polymer Prepared By One-step RAFT Polymerization

Stimuli-responsive polymers are a series of polymers which are able to respond rapidly to a few stimuli in external environment with mutations in the physical structures and chemical properties in the meantime. Stimulus responsive polymers have many species in response to p H, temperature, ionic strength, electromagnetic field and optical signals, etc. according to their sensitivity of the different stimulation.And they are able to respond to the stimulation of specific signals for recognition or achieve chain configuration and emerge the phase transition behavior of polymer. At present, stimuli-responsive polymers have been widely used in separation extraction,drug controlled release, tissue engineering, biological sensors and other fields.Therefore, designation and preparation of novel stimuli-responsive polymers have become frontiers and focuses in polymer field.In previous research, we prepared poly(ionic liquid)-based responsive nanogels by RAFT cross-linking copolymerization. Because of the indraught of carboxyl-containing chain transfer agent(CTA), the novel PIL-based nanogels exhibit reversible temperature-responsive and p H-responsive. The results show that the hydrogen bond interactions between carboxyl groups of CTA play important roles in thermoresponsive poly(ionic liquid)s-based nanogels. Based on this founding, we herein prepared functional ionic liquid-based thermosensitive polymer by inimer-type RAFT polymerization of NIPAM with CTA. Due to the introduction of carboxylate ions containing chain transfer agents(Inimer), the novel PIL-based polymer presented reversible temperature-responsive.In addition, we prepared novel salt-response poly(ionic liquid)-based nanogels by RAFT cross-linking copolymerization with a Inimer and ionic liquid monomers.The formation mechanism of poly(ionic liquid)s-based responsive nanogel prepared through RAFT cross-linking copolymerization was investigated, and the results indicated that the introduction of hydrogen bond interactions is key point to forming nanogels based on poly(ionic liquid)s salt responsive nanogel. Salt responsiveness of nanoparticles was characterized by dynamic light scattering in detail.The main contents include the following:1. Preparation of the ionic liquid monomers and chain transfer agent havedifferent compositions and structures include(4-vinylbenzyl-triphenyl phosphorous chloride ionic liquids(PILPh), 4-vinylbenzyl-tributylphosphorous chloride ionic liquids(PILBu), S-1-dodecyl-S'-(?, ?'-dimethyl-?"-acetic acid) trithiocarbonate(CTA2) and 4-vinylbenzyl-tributylphosphorous hydroxylate ionic liquids([PILBu]OH). It is obtained a Carboxylate ions-containing RAFT reagent(PILBu-CTA2, Inimer) by acid and alkali neutralization reaction, and these were characterized using 1H-NMR or 13C-NMR, FT-IR, MS and melting point.2. Preparation of poly(ionic liquid)-based thermosensitivity polymers is via one-step synthesis poly(ionic liquid)-based polymer by RAFT polymerization in selective solvents. It is an effective way to prepare different of molar ratio thermosensitive polymers by RAFT polymerization, due to introduction of a monomer of hydrophilic amide group and hydrophobic isopropyla(NIPAM) and Carboxylate ions of RAFT reagent(Inimer). The polymers were characterized using FT-IR, TGA, GPC, DLS and the responsive mechanism of polymer was discussed. In addition, when the macromolecular initiator was employed in the RAFT polymerization, the molecular weight of polymer increased, and this indicates that the polymerization is living polymerization.3. Preparation of poly(quaternary phosphonium salt ionic liquid)-based stimulus responsive nanogels, using a inimer as chain transfer agent, is via one-step synthesis poly(quaternary phosphonium salt ionic liquid)-based nanogels by RAFT cross-linking copolymerization in selective solvents. In our previous study, we found that the nanogels has thermosensitive and p H responsive by RAFT copolymerization.Further research shows that the nanogel is salt responsive. The nanogels were characterized using SEM, TGA, FT-IR, DLS and the salt-responsive mechanism of nanogels was discussed. It is also examined that particle size change of CLPNs with different of molar ratio Inimer following salt concentration, and reversibility of salt-responsive nanoparticles.