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.

Are (Co)Polymers of 1,1,3,3,3-Pentafluoropropene Possible?

The copolymerization and terpolymerization of 1,1,3,3,3-pentafluoropropene (PFP) with various combinations of fluorinated and hydrogenated comonomers were investigated. The chosen fluoromonomers were vinylidene fluoride (VDF), 3,3,3-trifluoropropene (TFP), hexafluoropropene (HFP), perfluoromethylvinyl ether (PMVE), chlorotrifluoroethylene (CTFE) and tert-butyl-2-trifluoromethacrylate (MAF-TBE), while the hydrocarbon comonomers were vinylene carbonate (VCA), ethyl vinyl ether (EVE) and 3-isopropenyl-α,α-dimethylbenzyl isocyanate (m-TMI). Copolymers of PFP with non-homopolymerizable monomers (HFP, PMVE and MAF-TBE) led to quite low yields, while the introduction of VDF enabled the synthesis of poly(PFP-ter-VDF-ter-M₃) terpolymers with improved yields. PFP does not homopolymerize and delays the copolymerizations. All polymers were either amorphous fluoroelastomers or fluorothermoplastics with glass transition temperatures ranging from -56 °C to +59 °C, and they exhibited good thermal stability in air.

RAFT Polymerization of Semifluorinated Monomers Mediated by a NIR Fluorinated Photocatalyst

Near-infrared (NIR) light plays an increasingly important role in the field of photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization due to its unique properties. Yet, the NIR photocatalyst with good stability for PET-RAFT polymerization remains promising. Here, a strategy of NIR PET-RAFT polymerization of semifluorinated monomers using fluorophenyl bacteriochlorin as a photocatalyst with strong absorption at the NIR light region (710-780 nm) is reported. In which, the F atoms are used to modify reduced tetraphenylporphyrin structure with enhanced photostability of photocatalyst. Under the irradiation of NIR light (λ_max = 740 nm), the PET-RAFT polymerization of semifluorinated methylacrylic monomers presents living/control characteristics and temporal modulation. By the PET-RAFT polymerization-induced self-assembly (PISA) strategy, stable fluorine-containing micelles are constructed in various solvents. In addition, the fluorinated hydrophobic surface is fabricated via a surface-initiated PET-RAFT (SI-PET-RAFT) polymerization using silicon wafer bearing RAFT agents with tunable surface hydrophobicity. This strategy not only enlightens the application of further modified compounds based on porphyrin structure in photopolymerization, but also shows promising potential for the construction of well-defined functional fluoropolymers.

Synthesis, aqueous solution behavior and self-assembly of a dual pH/thermo-responsive fluorinated diblock terpolymer

The synthesis of fluorinated dual-responsive block terpolymers via sequential reversible addition–fragmentation chain transfer (RAFT) polymerization is presented.

Phosphorus-Containing Fluoropolymers: State of the Art and Applications

Several strategies to synthesize fluorinated (co)polymers containing phosphorus groups and their applications are reviewed. First, original fluoromonomers bearing phosphorus atoms are supplied from relevant routes. They may possess fluorinated atoms linked to the ethylenic carbon atoms with different structures, such as F₂C═CF- or H₂C═C(CF₃)- and a phosphonated ω-function adjacent to an aliphatic or aromatic linker, while other monomers display a difluoromethylene dialkylphosphonate end group such as -CF₂-P(O)(OR)₂. Then, fluorinated copolymers were obtained according to various pathways: (i) by radical homopolymerization of monomers containing both fluorine and phosphorus atoms, (ii) by direct radical copolymerization of fluoromonomers and phosphorus-based monomers, or (iii) by chemical modification of fluorinated copolymers with phosphorus-based reactants. Conventional radical and controlled (or reversible deactivation radical polymerization, RDRP) copolymerization have also been explored. As for the chemical change of halogenated polymers, either conventional organic reactions (e.g., Arbuzov reaction from a chlorine, iodine, or bromine atom) or radiation grafting with specific monomers led to graft copolymers composed of a fluorinated backbone and phosphonated grafts. This second part also details aliphatic and aromatic fluorophosphorous copolymers in which dialkylphosphonates or phosphonic acids are reported. Finally, since fluorine and phosphorus atoms bring complementary relevant properties (low refractive index and dielectric constants, chemical inertness, high electrochemical, soils, and heat resistances, electroattractivity from fluorine atoms and high acidity, complexation, anticorrosion, flame retardant, and biomedical properties from phosphorus ones), synergetic characteristics have been targeted. These properties allow such fluoro-phosphorus (co)polymers to be used as novel materials involved in various applications such as polymer exchange membranes for fuel cells, self-etching adhesives for dental materials, adhesion promoters, flame retardants, polymer blends, and anticorrosive coatings.

Use of poly(vinylidene fluoride-co-vinyl dimethylphosphonate) copolymers for efficient extraction of valuable metals

The radical copolymerisation of vinylidene fluoride (VDF) with vinyl dimethyl phosphonate (VDMP) initiated by various kinds of initiators is presented.

Core–shell structured poly(vinylidene fluoride)-grafted-BaTiO3 nanocomposites prepared via reversible addition–fragmentation chain transfer (RAFT) polymerization of VDF for high energy storage capacitors

Core–shell structured PVDF-g-BaTiO₃ nanocomposites were prepared by surface-initiated RAFT of VDF from BaTiO₃ nanoparticles.

CuAAC click chemistry: a versatile approach towards PVDF-based block copolymers

Functionalized benzoyl peroxide-initiated polymerization of vinylidene fluoride allows straightforward preparation of PVDF-based block copolymers with an appealing crystallization behavior.

Kinetics of radical copolymerization of vinylidene fluoride with tert-butyl 2-trifluoromethyl acrylate: a suitable pair for the synthesis of alternating fluorinated copolymers

A study of the copolymerization kinetics of vinylidene fluoride with tert-butyl 2-trifluoromethyl acrylate: a suitable pair for the synthesis of alternating fluorinated copolymers.

Thermal and photo-RAFT polymerization of 2,2,2-trifluoroethyl α-fluoroacrylate

RAFT polymerization of 2,2,2-trifluoroethyl α-fluoroacrylate (FATRIFE) was studied under thermal conditions and light irradiation in the presence of four chain transfer agents. Polymers with narrow dispersities were obtained in the presence of trithiocarbonate CTA₂, and this further led to fluorinated block copolymers.

Synthesis and properties of poly(trifluoroethylene)viaa persistent radical mediated polymerization of trifluoroethylene

Poly(trifluoroethylene) exhibiting excellent thermal stability was synthesized by the radical polymerization of trifluoroethylene initiated by an innovative persistent radical.

Syntheses of 2-(trifluoromethyl)acrylate-containing block copolymers via RAFT polymerization using a universal chain transfer agent

2-(Trifluoromethyl)acrylate-containing block copolymers were synthesized via RAFT polymerization using a universal CTA.

Bis(formylphenolato)cobalt(II)-Mediated Alternating Radical Copolymerization of tert-Butyl 2-Trifluoromethylacrylate with Vinyl Acetate

The organometallic-mediated radical polymerization (OMRP) of vinyl acetate (VAc) and its OMR copolymerization (OMRcoP) with tert-butyl 2-trifluoromethylacrylate (MAF-TBE) mediated by Co(SAL)₂ (SAL = 2-formylphenolato or deprotonated salicylaldehyde) produced relatively well-defined PVAc and poly(VAc-alt-MAF-TBE) copolymers at moderate temperature (<40 °C) in bulk. The resulting alternating copolymer was characterized by ¹H-, 13C- and 19F-nuclear magnetic resonance (NMR) spectroscopies, and by size exclusion chromatography. The linear first-order kinetic plot, the linear evolutions of the molar mass with total monomer conversion, and the relatively low dispersity (Đ~1.55) of the resulting copolymers suggest that this cobalt complex provides some degree of control over the copolymerization of VAc and MAF-TBE. Compared to the previously investigated cobalt complex OMRP mediators having a fully oxygen-based first coordination sphere, this study emphasizes a few peculiarities of Co(SAL)₂: a lower ability to trap radical chains as compared to Co(acac)₂ and the absence of catalytic chain transfer reactions, which dominates polymerizations carried in the presence of 9-oxyphenalenone cobalt derivative.

Poly(vinylidene fluoride) Containing Phosphonic Acid as Anticorrosion Coating for Steel

Vinylidene fluoride (VDF)-based copolymers bearing pendant phosphonic acid function for potential application as anticorrosion coatings were synthesized via free radical copolymerization of VDF with a new phosphorus containing 2-trifluoromethacrylate monomer, (dimethoxyphosphoryl)methyl 2-(trifluoromethyl)acrylate (MAF-DMP). MAF-DMP was prepared from 2-trifluoromethacrylic acid in 60% overall yield. Radical copolymerizations of VDF with MAF-DMP initiated by tert-amyl peroxy-2-ethylhexanoate at varying ([VDF]₀/[MAF-DMP]₀) feed ratios led to several poly(VDF-co-MAF-DMP) copolymers having different molar percentages of VDF (79-96%) and number-average molecular weights (M_n's) up to ca. 10 000 g mol^-1 in fair yields (47-53%). Determination of the composition and microstructure of all the synthesized copolymers was done by ¹H and ¹⁹F NMR spectroscopies. The monomer reactivity ratios of this new VDF/MAF-DMP pair were also determined (r_VDF = 0.76 ± 0.34 and r_MAF-DMP = 0 at 74 °C). The resulting poly(VDF-co-MAF-DMP) copolymers exhibited high melting temperature (162-171 °C, with respect to the VDF content), and the degree of crystallinity reached up to 51%. Finally, the pendant dimethyl phosphonate ester groups of the synthesized poly(VDF-co-MAF-DMP) copolymer were quantitatively hydrolyzed, giving rise to novel phosphonic acid-functionalized PVDF (PVDF-PA). In comparison to hydrophobic poly(VDF-co-MAF-DMP) copolymers (the water contact angle, WCA, was 98°), the hydrophilic character of the PVDF-PA was found to be surprisingly rather pronounced, exhibiting low WCA (15°). Finally, steel plates coated with PVDF-PA displayed satisfactory anticorrosion properties under simulated seawater environment.

Poly(fluoroacrylate)s with tunable surface hydrophobicity via radical copolymerization of 2,2,2-trifluoroethyl α-fluoroacrylate and 2-(trifluoromethyl)acrylic acid

Fluorinated polyacrylates with tunable surface hydrophobicity are prepared via radical copolymerization of an α-fluoroacrylate and 2-(trifluoromethyl)acrylic acid.

Synthesis, characterization, and thermal and surface properties of co- and terpolymers based on fluorinated α-methylstyrenes and styrene

Conventional bulk radical co- and terpolymerizations of α-fluoromethylstyrene (FMST) or/and α-trifluoromethylstyrene (TFMST) with styrene (ST) initiated by α,α′-azobis(isobutyronitrile) (AIBN) are presented.

Ferroelectric fluorinated copolymers with improved adhesion properties

Modified fluorinated electroactive poly(VDF-co-TrFE) copolymers with improved adhesion properties, on glass or metal substrates, are presented.

Determination and correlation of regioselectivity and dead dormant species from head addition in acrylate RAFT polymerization

The dead dormant species from head addition in a RAFT process can be separated and quantified by combining chain-extension and GPEC.

An amphiphilic poly(vinylidene fluoride)-b-poly(vinyl alcohol) block copolymer: synthesis and self-assembly in water

This study is the first report of the synthesis and self-assembly in water of an amphiphilic PVDF-b-PVA block copolymer.

Supramolecular semifluorinated dendrons glued by weak hydrogen-bonds

Uniform nanoparticles with a diameter of ∼50 nm were generated from supramolecular semifluorinated dendritic networks, driven by weak heterocomplementary hydrogen-bonding moieties.

Nitroxide-Mediated Alternating Copolymerization of Vinyl Acetate with tert-Butyl-2-trifluoromethacrylate Using a SG1-Based Alkoxyamine

Unique alternating copolymers based on vinyl acetate (VAc) and tert-butyl-2-trifluoromethacrylate (MAF-TBE, a nonhomopolymerizable monomer under radical conditions) have been synthesized by nitroxide-mediated polymerization (NMP) using a SG1-based BlocBuilder alkoxyamine (MAMA-SG1) at moderate temperature (at 40 °C) in dimethyl sulfoxide. First-order kinetics and linear evolutions of the molecular weight (up to 17100 g mol^-1), maintaining low dispersity values (Đ ≤ 1.33), confirmed the controlled nature of the copolymerization. Interestingly, none of the starting monomers could undergo homopolymerization under the NMP condition initiated by MAMA-SG1. The resulting alternating copolymers were characterized by ¹H, ¹³C, ¹⁹F, and ³¹P NMR spectroscopies and size exclusion chromatography (SEC). The poly(VAc-alt-MAF-TBE) copolymer is amorphous and exhibited a single glass transition temperature of 59 °C. This is the first report of nitroxide-mediated (co)polymerization of VAc leading to well-defined copolymers with satisfactory yields. The results presented in this study established a new route via NMP toward the synthesis of strictly 1:1 alternating fluorocopolymers that can display diverse functionalities.

Photomediated Controlled Radical Polymerization and Block Copolymerization of Vinylidene Fluoride

This review summarizes recent research on novel photochemical methods for the initiation and control of the polymerization of main chain fluorinated monomers as exemplified by vinylidene fluoride (VDF) and for the synthesis of their block copolymers. Such reactions can be carried out at ambient temperature in glass tubes using visible light. Novel, original protocols include the use of hypervalent iodide carboxylates alone or in conjunction with molecular iodine, as well as the use of photoactive transition metal carbonyls in the presence of alkyl, fluoroalkyl, and perfluoroalkyl halides. An in-depth study of the reaction parameters highlights the use of dimethyl carbonate as a preferred polymerization solvent and outlines the structure-property relationship for hypervalent iodide carboxylates and halide initiators in both the free radical and iodine degenerative transfer controlled radical polymerization (IDT-CRP) of VDF. Finally, the rational selection of metal carbonyls that are successful not only as IDT mediators but, more importantly, in the quantitative activation of both PVDF-CH2-CF2-I and PVDF-CF2-CH2-I chain ends toward the synthesis of well-defined PVDF block copolymers is presented.

RAFT synthesis of well-defined PVDF-b-PVAc block copolymers

This article reports that PVDF-b-PVAc diblock copolymers can be synthesized by RAFT polymerization from PVDF macroCTAs and rationalizes this discovery using DFT calculations.

One-pot synthesis of poly(vinylidene fluoride) methacrylate macromonomers via thia-Michael addition

A comparison of two one-pot methods to prepare methacrylate PVDF-macromonomers and the synthesis of PVDF-containing block copolymers.

Towards new strategies for the synthesis of functional vinylidene fluoride-based copolymers with tunable wettability

–COOH functionalized poly(vinylidene fluoride) prepared using water-based non-fluorinated solvents displays tunable wettability suitable for potential application in coating, oil recovery and water purification.