Macromolecular engineering approach for the preparation of new architectures from fluorinated olefins and their applications

Light-Driven Organocatalyzed Controlled Radical Copolymerization of (Perfluoroalkyl)ethylenes and Vinyl Esters/Amides

Fluoropolymers of well-defined structures exhibit significant potential in a broad range of high-tech applications. However, the controlled synthesis of fluoropolymers from easily available monomers remains difficult. In this work, we report the development of an organocatalyzed controlled radical copolymerization of (perfluoroalkyl)ethylenes (PFAEs) and unconjugated vinyl monomers (UCMs) under light irradiation, which has enabled on-demand access toward side-chain fluorinated polymers under metal-free conditions. This method furnishes a large variety of polymers with diverse fluoroalkyl and ester/amide as pendent groups, tunable molar masses, and low dispersities (ca. Đ = 1.1-1.3), and adjustable fractions of PFAE and UCM units. Obtained fluoropolymers exhibit good chain-end fidelity and activity, allowing chain-extension polymerizations to prepare block copolymers of complicated compositions. Furthermore, the PFAE copolymers exhibit outstanding light transmission and low refractive index.

Synthesis of Ultrahigh Molecular Weight Poly (Trifluoroethyl Methacrylate) Initiated by the Combination of Palladium Nanoparticles with Organic Halides

Ultrahigh molecular weight polymers display outstanding properties and have great application potential. However, the traditional polymerization methods have inevitable disadvantages that challenge the green synthesis of ultrahigh molecular weight polymers. The paper achieved an ultrahigh molecular weight poly (trifluoroethyl methacrylate) via a novel polymerization and discussed the mechanistic, kinetic, and experimental aspects. The combination of palladium nanoparticles with ethyl 2-bromopropionate has been identified as an exceedingly efficient system for initiating the polymerization of trifluoroethyl methacrylate. An ultrahigh molecular weight poly (trifluoroethyl methacrylate) with a number-average molecular weight up to 3.03 × 106 Da has been synthesized at a feeding molar ratio of [poly (trifluoroethyl methacrylate)]/[ethyl 2-bromopropionate]/[palladium nanoparticles] = 3.95 × 104:756:1 at 70 °C. The reaction orders concerning palladium nanoparticles, ethyl 2-bromopropionate, and poly (trifluoroethyl methacrylate) were determined to be 0.59, 0.34, and 1.38, respectively. By analyzing a series of characterizations, we verified that the polymerization of poly (trifluoroethyl methacrylate) was initiated by the ethyl 2-bromopropionate residue radicals, which were generated from the interaction between palladium nanoparticles and ethyl 2-bromopropionate. The comparatively large size of the palladium nanoparticles provided a barrier to chain-growing radicals, promoting the synthesis of ultrahigh molecular weight polymers.

Enhanced Antifouling Capability of In Situ-Grown Hydrophilic-Hydrophobic Nanodomains on Membrane Surface in the Ultralow Pressurized Ultrafiltration Process

Although hydrophilic modification of the membrane surface is widely adopted, polymeric membranes still suffer from irreversible fouling caused by hydrophilic components in surface water. Here, an ultrathin hydrogel layer (40 nm) with hydrophilic-hydrophobic textures was in situ grown onto the polysulfone ultrafiltration membrane surface using an organic-radical-initiated interfacial polymerization technique. The interfacial polymerization of hydrophilic and hydrophobic monomers ensured the molecular-scale distribution of hydrophilic and hydrophobic nanodomains on the membrane surface. These nanodomains, with their molecular lengths, facilitated dynamic repulsion interactions between the uniformly textured surface and foulant components with different degrees of hydrophilicity. Chemical force characterization confirmed that the adhesion force between the hydrophilic-hydrophobic textured membrane surface and foulants (dodecane, bovine serum albumin, and humic acid) was greatly reduced. Dynamic filtration experiments showed that a hydrophilic-hydrophobic textured membrane always possessed the largest water flux and the best antifouling performance. Furthermore, the foulant coverage ratio on the membrane surface was first evaluated by measuring changes in surface streaming potentials, which demonstrated a 69% reduction in the amount of foulant adhering to the hydrophilic-hydrophobic textured membrane surface. Therefore, the construction of hydrophilic-hydrophobic nanodomains on the membrane surface provides a promising strategy for alleviating membrane fouling caused by both hydrophobic and hydrophilic components during ultralow pressurized ultrafiltration processes.

Fluorinated Organic Polymers for Cancer Drug Delivery

In the realm of cancer therapy, the spotlight is on nanoscale pharmaceutical delivery systems, especially polymer-based nanoparticles, for their enhanced drug dissolution, extended presence in the bloodstream, and precision targeting achieved via surface engineering. Leveraging the amplified permeation and retention phenomenon, these systems concentrate therapeutic agents within tumor tissues. Nonetheless, the hurdles of systemic toxicity, biological barriers, and compatibility with living systems persist. Fluorinated polymers, distinguished by their chemical idiosyncrasies, are poised for extensive biomedical applications, notably in stabilizing drug metabolism, augmenting lipophilicity, and optimizing bioavailability. Material science heralds the advent of fluorinated polymers that, by integrating fluorine atoms, unveil a suite of drug delivery merits: the hydrophobic traits of fluorinated alkyl chains ward off lipid or protein disruption, the carbon-fluorine bond's stability extends the drug's lifecycle in the system, and a lower alkalinity coupled with a diminished ionic charge bolsters the drug's ability to traverse cellular membranes. This comprehensive review delves into the utilization of fluorinated polymers for oncological pharmacotherapy, elucidating their molecular architecture, synthetic pathways, and functional attributes, alongside an exploration of their empirical strengths and the quandaries they encounter in both experimental and clinical settings.

Organocatalyzed Photo-Controlled Synthesis of Ultrahigh-Molecular-Weight Fluorinated Alternating Copolymers

Ultrahigh-molecular-weight (UHMW) polymers with tailored structures are highly desirable for the outstanding properties. In this work, we developed a novel photoorganocatalyzed controlled radical alternating copolymerizations of fluoroalkyl maleimide and diverse vinyl comonomers, enabling efficient preparation of fluorinated copolymers of predetermined UHMWs and well-defined structures at high conversions. Versatility of this method was demonstrated by expanding to controlled terpolymerization, which allows facial access toward fluorinated terpolymers of UHMWs and functional pendants. The obtained copolymers exhibited attractive physical properties and furnished thermoplastic, anticorrosive and (super)hydrophobic attributes as coatings on different substrates. Molecular simulations provided insights into the coating morphology, which unveiled a fluorous protective layer on the top surface with polar groups attached to the bottom substrate, resulting in good adhesion and hydrophobicity, simultaneously. This synthetic method and customized copolymers shed light on the design of high-performance coatings by macromolecular engineering.

Macromolecular Engineered Multifunctional Room-Temperature Phosphorescent Polymers through Reversible Deactivation Radical Polymerization

Despite the intensive research in room-temperature phosphorescent (RTP) polymers, the synthesis of RTP polymers with well-defined macromolecular structures and multiple functions remains a challenge. Herein, reversible deactivation radical polymerization was demonstrated to offer a gradient copolymer (GCP) architecture with controlled heterogeneities, which combines hard segment and flexible segment. The GCPs would self-assemble into a multiphase nanostructure, featuring tunable stretchability, excellent RTP performance, and intrinsic healability without compromising light emission under stretching. The mechanical performance is tunable on demand with elongation at break ranging from 5.0% to 221.7% and Young's modulus ranging from 0.5 to 225.0 MPa.

Controlled Radical Copolymerization toward Well-Defined Fluoropolymers

In the past 80 years, fluoropolymers have found broad applications in both industrial and academic settings, owing to their unique physicochemical properties. Copolymerizations of fluoroalkene feedstocks present an important avenue to obtain high-performance materials by merging intrinsic attributes of fluorocarbons and great versatility of comonomers. Recently, while massive investigations have disclosed the great potentials of precisely synthesized polymers, researchers have made considerable efforts to approach well-defined fluorinated copolymers. This minireview discusses challenges in controlled radical copolymerizations (CRCPs) of fluoroalkenes and provides a concise perspective on recent progress in CRCPs of fluoroalkenes (e.g., tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropene, perfluoroalkyl vinyl ethers) with non-fluorinated vinyl comonomers, which have enabled on-demand preparations of various main-chain fluoropolymers with predefined molar masses, low dispersities, as well as regulable chemical compositions and sequences. The synthetic advantages of CRCPs will promote controlled and facile access to customized fluoropolymers for high-tech applications such as batteries, coatings and so on.

Fluoropolymer Nanoparticles Synthesized via Reversible-Deactivation Radical Polymerizations and Their Applications

Fluorinated polymeric nanoparticles (FPNPs) combine unique properties of fluorocarbon and polymeric nanoparticles, which has stimulated massive interest for decades. However, fluoropolymers are not readily available from nature, resulting in synthetic developments to obtain FPNPs via free radical polymerizations. Recently, while increasing cutting-edge directions demand tailored FPNPs, such materials have been difficult to access via conventional approaches. Reversible-deactivation radical polymerizations (RDRPs) are powerful methods to afford well-defined polymers. Researchers have applied RDRPs to the fabrication of FPNPs, enabling the construction of particles with improved complexity in terms of structure, composition, morphology, and functionality. Related examples can be classified into three categories. First, well-defined fluoropolymers synthesized via RDRPs have been utilized as precursors to form FPNPs through self-folding and solution self-assembly. Second, thermally and photoinitiated RDRPs have been explored to realize in situ preparations of FPNPs with varied morphologies via polymerization-induced self-assembly and cross-linking copolymerization. Third, grafting from inorganic nanoparticles has been investigated based on RDRPs. Importantly, those advancements have promoted studies toward promising applications, including magnetic resonance imaging, biomedical delivery, energy storage, adsorption of perfluorinated alkyl substances, photosensitizers, and so on. This Review should present useful knowledge to researchers in polymer science and nanomaterials and inspire innovative ideas for the synthesis and applications of FPNPs.

Designing F/P Hybrid Polymer as Ultrastable Cationic Shielding Interphase for High-Performance Lithium Metal Batteries

Dendrite growth on electrode-electrolyte interphase has severely limited applications of lithium metal batteries (LMBs). Here, we developed an ionic alternating polymer with fluorocarbons and phosphonium cations in repeating units to regulate Li deposition for the first time. The combined functionalities in the F/P hybrid polymer exhibit remarkable characteristics as a protective layer on top of Li anode, demonstrating outstanding electrochemical stability, ion flux redistributing capability and adaptive chain mobility. Based on characterizations and simulations, this cationic interlayer could effectively furnish long-standing electrostatic shielding for anodes, allowing restrained coating decomposition and homogenized electric field distribution to induce dendrite-free Li deposition, and enabling full cells with enhanced rate and long-term cycling performance. Given the importance of LMBs, this work will promote polymer design to stabilize anodes with superior electrochemical behavior.

Organocatalyzed Controlled Radical Copolymerization toward Hybrid Functional Fluoropolymers Driven by Light

Photo-controlled polymerizations are attractive to tailor macromolecules of complex compositions with spatiotemporal regulation. In this work, with a convenient synthesis for trifluorovinyl boronic ester (TFVB), we report a light-driven organocatalyzed copolymerization of vinyl monomers and TFVB for the first time, which enabled the controlled synthesis of a variety of hybrid fluorine/boron polymers with low dispersities and good chain-end fidelity. The good behaviors of "ON/OFF" switch, chain-extension polymerizations and post-modifications further highlight the versatility and reliability of this copolymerization. Furthermore, we demonstrate that the combination of fluorine and boron could furnish copolymer electrolytes of high lithium-ion transference number (up to 0.83), bringing new opportunities of engineering high-performance materials for energy storage purposes.

PVDF-Based Fluoropolymer Modifications via Photoinduced Atom Transfer Radical Polymerizations

Graft modifications of PVDF fluoropolymers have been identified as the efficient route to improve the properties and expand the applications. Taking advantage of C-F and C-Cl bonds in the repeat units, atom transfer radical polymerizations (ATRP) were widely used for graft modification. Recently, photoinduced ATRP has shown good spatial and temporal control over the polymerization process in contrast to thermal activation mode. This minireview highlights the progress in PVDF-based fluoropolymer modifications by using photoinduced Cu(II)-mediated ATRP and organocatalyzed ATRP. The challenges and opportunities are proposed with the aim at advancing the development of synthesis and applications of fluoropolymer.

RAFT-Based Polymers for Click Reactions

The parallel development of reversible deactivation radical polymerization and click reaction concepts significantly enriches the toolbox of synthetic polymer chemistry. The synergistic effect of combining these approaches manifests itself in a growth of interest to the design of well-defined functional polymers and their controlled conjugation with biomolecules, drugs, and inorganic surfaces. In this review, we discuss the results obtained with reversible addition-fragmentation chain transfer (RAFT) polymerization and different types of click reactions on low- and high-molar-mass reactants. Our classification of literature sources is based on the typical structure of macromolecules produced by the RAFT technique. The review addresses click reactions, immediate or preceded by a modification of another type, on the leaving and stabilizing groups inherited by a growing macromolecule from the chain transfer agent, as well as on the side groups coming from monomers entering the polymerization process. Architecture and self-assembling properties of the resulting polymers are briefly discussed with regard to their potential functional applications, which include drug delivery, protein recognition, anti-fouling and anti-corrosion coatings, the compatibilization of polymer blends, the modification of fillers to increase their dispersibility in polymer matrices, etc.

Visible-Light-Enabled Organocatalyzed Controlled Alternating Terpolymerization of Perfluorinated Vinyl Ethers

Polymerizations of perfluorinated vinyl ethers (PFVEs) provide an important category of fluoropolymers that have received considerable interests in applications. In this work, we report the development of an organocatalyzed controlled radical alternating terpolymerization of PFVEs and vinyl ethers (VEs) under visible-light irradiation. This method not only enables the synthesis of a broad scope of fluorinated terpolymers of low dispersities and high chain-end fidelity, facilitating tuning the chemical compositions by rationally choosing the type and/or ratio of comonomers, but also allows temporal control of chain-growth, as well as the preparation of a variety of novel fluorinated block copolymers. To showcase the versatility of this method, fluorinated alternating terpolymers have been synthesized and customized to simultaneously display a variety of desirable properties for solid polymer electrolyte design, creating new opportunities in high-performance energy storage devices.

RAFT polymerisation of trifluoroethylene: the importance of understanding reverse additions

This article is the first report of the RAFT polymerisation of trifluoroethylene (TrFE).

Photocontrolled bromine–iodine transformation reversible-deactivation radical polymerization: facile synthesis of star copolymers and unimolecular micelles

A facile strategy of synthesizing star copolymers was successfully established via photocontrolled BIT-RDRP. The obtained copolymers have well-defined four-arm amphiphilic block architecture and can form stable unimolecular micelles in water.

Facile access to functional polyacrylates with dual stimuli response and tunable surface hydrophobicity

Well-defined functional polyacrylates with dual stimuli response and tunable surface hydrophobicity were synthesized via the recyclable Ni–Co alloy catalyzed reversible deactivation radical polymerization technique at ambient temperature.

Recent advances in the preparation of semifluorinated polymers

Synthesis of semifluorinated polymers containing fluorous groups on the backbone or as side chains is an increasingly popular field of research.

Fluoropolymers in biomedical applications: state-of-the-art and future perspectives

Biomedical applications of fluoropolymers in gene delivery, protein delivery, drug delivery, ¹⁹F MRI, PDT, anti-fouling, anti-bacterial, cell culture, and tissue engineering.

Investigations into CTA-differentiation-involving polymerization of fluorous monomers: exploitation of experimental variances in fine-tuning of molecular weights

Condition and substrate effects on CTA-differentiation-involving polymerization were explored for logical control of molecular weight.