Facile Fabrication of CO2-Responsive Nanofibers from Photo-Cross-Linked Poly(pentafluorophenyl acrylate) Nanofibers

CO₂-responsive nanofibers were facilely prepared from photo-cross-linked poly(pentafluorophenyl acrylate) (PPFPA) nanofibers via "amine-active ester" chemical modification. Photo-cross-linked PPFPA nanofibers were modified with histamine under mild conditions to generate cross-linked poly(histamine acrylamide) (PHAAA) nanofibers featuring a CO₂ responsiveness. As expected, the prepared cross-linked PHAAA nanofibers can exhibit a CO₂-responsive behavior to induce a reversible transition from hydrophobic to hydrophilic upon alternating addition and removal of CO₂ on the surface of nanofibrous membranes. Based on this finding, we could demonstrate that cross-linked PHAAA nanofibers can be employed for reversible absorption and release of protein using bovine serum albumin (BSA) as a model.

CO2-Responsive polymer materials

This paper reviews the chemical fundamentals of CO₂-responsive polymers as well as the latest reported “smart” material systems switched by CO₂.

Oxygen and Carbon Dioxide Dual Gas-Switchable Thermoresponsive Homopolymers

Herein, we report the first oxygen (O₂) and carbon dioxide (CO₂) dual gas-switchable thermoresponsive polymers based on a newly synthesized monomer N-(2-fluoroethyl amide)-N-(2-(diethylamino)ethyl) acrylamide, that is, AM(F1EA-DEAE), which bears both O₂-switchable fluorinated ethyl amide (F1EA) and CO₂-switchable N,N-diethylamino ethyl (DEAE) moieties on its side chain. PolyAM(F1EA-DEAE) samples prepared from reversible addition-fragmentation chain transfer (RAFT) polymerization exhibited good temperature-responsive properties. Their inherent low critical solution temperature (LCST) could be reversibly tuned to different levels by respectively purging O₂ or CO₂ into its aqueous solution. The O₂-treatment shifted LCST to a higher temperature, while the CO₂-treatment made the polymer fully water-soluble. The polymer could be readily recovered to its initial state by washing off the trigger gas with an inert gas such as nitrogen. This work provides an effective monomer design approach for the preparation of O₂ and CO₂ dual gas-responsive polymers.

Thiol-reactive functional poly(meth)acrylates: multicomponent monomer synthesis, RAFT (co)polymerization and highly efficient thiol–para-fluoro postpolymerization modification

Novel Passerini-made pentafluorophenyl-functional (meth)acrylate monomers are (co)polymerized by RAFT and modified quantitatively with a variety of functional primary, secondary, and tertiary thiols.

Ethanolic RAFT Dispersion Polymerization of 2-(Naphthalen-2-yloxy)ethyl Methacrylate and 2-Phenoxyethyl Methacrylate with Poly[2-(dimethylamino)ethyl Methacrylate] Macro-Chain Transfer Agents

The ethanolic reversible addition-fragmentation chain transfer dispersion polymerization (RAFTDP), at 21 wt-%, of 2-(naphthalen-2-yloxy)ethyl methacrylate (NOEMA) and 2-phenoxyethyl methacrylate (POEMA) with a poly[2-(dimethylamino)ethyl methacrylate] macro-chain transfer agent (CTA) with an average degree of polymerization of 20 (PDMAEMA20) is described. DMAEMA20-b-NOEMAy (y = 20–125) block copolymers were readily prepared under dispersion conditions in ethanol at 70°C. However, the polymerization of NOEMA was not well controlled, with size exclusion chromatograms being distinctly bi or multimodal with measured dispersities . Though NOEMA copolymerization was not ideal, the resulting series of block copolymers did exhibit the anticipated full spectrum of nanoparticle morphologies (spheres, worms, and vesicles). Interestingly, these morphology transitions occurred over a relatively narrow range of block copolymer compositions. In the case of POEMA, copolymerization was also poorly controlled with 1.50 ≤ ĐM ≤ 1.83 for the series of DMAEMA20-b-POEMAy copolymers. In contrast to the NOEMA-based copolymers, the POEMA series only yielded nanoparticles with a spherical morphology whose size increased with increasing average degrees of polymerization of the POEMA block. Collectively, though both NOEMA and POEMA can be utilized in ethanolic RAFT dispersion polymerization formulations, these preliminary studies suggest that neither appears to be an ideal aryl methacrylate choice as comonomer, especially if the goal is to combine the synthesis of well-defined copolymers with efficient nanoparticle formation.

UCST behavior of polyampholytes based on stoichiometric RAFT copolymerization of cationic and anionic monomers

Polyampholytes with controlled equimolar ratio of charges were synthesized by reversible addition–fragmentation chain transfer (RAFT) copolymerization of cationic and anionic monomers and their UCST behavior is reported.

The synthesis and aqueous solution properties of sulfobutylbetaine (co)polymers: comparison of synthetic routes and tuneable upper critical solution temperatures

With an additional methyl group in the ion bridge, sulfobutylbetaine (co)polymers show significantly higher UCSTs than their more common sulfopropylbetaine counterparts making them a promising class of smart materials.