Controlled Synthesis of Poly(vinylamine)-Based Copolymers by Organometallic-Mediated Radical Polymerization

Mechanically triggered on-demand degradation of polymers synthesized by radical polymerizations

Polymers that degrade on demand have the potential to facilitate chemical recycling, reduce environmental pollution and are useful in implant immolation, drug delivery or as adhesives that debond on demand. However, polymers made by radical polymerization, which feature all carbon-bond backbones and constitute the most important class of polymers, have proven difficult to render degradable. Here we report cyclobutene-based monomers that can be co-polymerized with conventional monomers and impart the resulting polymers with mechanically triggered degradability. The cyclobutene residues act as mechanophores and can undergo a mechanically triggered ring-opening reaction, which causes a rearrangement that renders the polymer chains cleavable by hydrolysis under basic conditions. These cyclobutene-based monomers are broadly applicable in free radical and controlled radical polymerizations, introduce functional groups into the backbone of polymers and allow the mechanically gated degradation of high-molecular-weight materials or cross-linked polymer networks into low-molecular-weight species.

Controlled Radical Copolymerization toward Tailored F/N Hybrid Polymers by Using Light-Driven Organocatalysis

Controlled radical copolymerizations present attractive avenues to obtain polymers with complicated compositions and sequences. In this work, we report the development of a visible-light-driven organocatalyzed controlled copolymerization of fluoroalkenes and acyclic N-vinylamides for the first time. The approach enables the on-demand synthesis of a broad scope of amide-functionalized main-chain fluoropolymers via novel fluorinated thiocarbamates, facilitating regulations over chemical compositions and alternating fractions by rationally selecting comonomer pairs and ratios. This method allows temporally controlled chain-growth by external light, and maintains high chain-end fidelity that promotes facile preparation of block sequences. Notably, the obtained F/N hybrid polymers, upon hydrolysis, afford free amino-substituted fluoropolymers versatile for post modifications toward various functionalities (e.g., amide, sulfonamide, carbamide, thiocarbamide). We further demonstrate the in situ formation of polymer networks with desirable properties as protective layers on lithium metal anodes, presenting a promising avenue for advancing lithium metal batteries.

Poly(N-methyl-N-vinylacetamide): A Strong Alternative to PEG for Lipid-Based Nanocarriers Delivering siRNA

Lipid-based nanocarriers have demonstrated high interest in delivering genetic material, exemplified by the success of Onpattro and COVID-19 vaccines. While PEGylation imparts stealth properties, it hampers cellular uptake and endosomal escape, and may trigger adverse reactions like accelerated blood clearance (ABC) and hypersensitivity reactions (HSR). This work highlights the great potential of amphiphilic poly(N-methyl-N-vinylacetamide) (PNMVA) derivatives as alternatives to lipid-PEG for siRNA delivery. PNMVA compounds with different degrees of polymerization and hydrophobic segments, are synthesized. Among them, DSPE (1,2-distearoyl-sn-glycero-3-phosphoethanolamine)-PNMVA efficiently integrates into lipoplexes and LNP membranes and prevents protein corona formation around these lipid carriers, exhibiting stealth properties comparable to DSPE-PEG. However, unlike DSPE-PEG, DSPE-PNMVA24 shows no adverse impact on lipoplexes cell uptake and endosomal escape. In in vivo study with mice, DSPE-PNMVA24 lipoplexes demonstrate no liver accumulation, indicating good stealth properties, extended circulation time after a second dose, reduced immunological reaction, and no systemic pro-inflammatory response. Safety of DSPE-PNMVA24 is confirmed at the cellular level and in animal models of zebrafish and mice. Overall, DSPE-PNMVA is an advantageous substitute to DSPE-PEG for siRNA delivery, offering comparable stealth and toxicity properties while improving efficacy of the lipid-based carriers by minimizing the dilemma effect and reducing immunological reactions, meaning no ABC or HSR effects.

Multi-responsive γ-methylene-γ-butyrolactone/N-vinyl caprolactam copolymers involving pH-dependent reversible lactonization

Copolymerization of γ-methylene-γ-butyrolactone with N-vinyl caprolactam leads to a peculiar multi-responsive NVCL-based system involving a unique reversible pH-dependent ring opening/closure of the pendant lactones.

RAFT polymerisation of N-vinylformamide and the corresponding double hydrophilic block copolymers

Polyvinylamine-based double hydrophilic block copolymers are synthesised from RAFT polymerisation of N-vinylformamide.

"Button and Buttonhole" Supramolecular Structure Enables the Self-Healing Behaviors of Functionalized Poly(ether sulfone) Membranes for Osmotic Power Generation

Osmotic power generation has emerged as an advanced technology toward water-energy nexus to tackle global water pollution. It provides a sustainable use of salinity gradient from water resources yet encounters major obstacles caused by pressure-retarded osmosis (PRO) membrane fouling. Although membranes with good antifouling properties are widely studied, their antifouling functions are readily lost when scratches or detachments occur through physical damage during operation and chemical degradation by water and corrosive foulants. Consequently, it is important to develop antifouling membranes with autonomous self-healing capabilities. Herein, self-healable functionalized poly(ether sulfone) (PES) antifouling membranes have been fabricated via the sequential conjugation of the zwitterionic random copolymer [poly(1-(1-(1-adamantylcarbonyloxy)methyl)-3-vinylimidazolium bromide-co-1-(3-sulfopropyl)-3-vinylimidazolium-co-vinylamine)] (P(ADVI-co-SBVI-co-VA), abbreviated as PASV copolymer) and linear cyclodextrin polymer (LPCD) on polydopamine-preactivated PES supports. The self-healing behaviors rely on the judiciously designed "button-and-buttonhole" supramolecular network. Specifically, β-cyclodextrins in LPCD and adamantines in PASV act as "buttonholes" and "buttons", respectively. Under physical and chemical damages, the β-cyclodextrin "buttonhole" may sacrificially detach from the adamantine "button" of PASV but then recap another adamantine to restore the protective function. The antifouling and self-healing traits of as-functionalized PES-g-PASV-LPCD membranes were demonstrated by the superior antiprotein behaviors and improved antimicrobial performances on both nonaged and aged samples. In the PRO process, the modified membranes were effective in mitigating organic fouling and exhibited higher power density (79% of the initial value) than the nonmodified ones (47% of the initial value) in municipal wastewater testing. The strategy for engineering inherently healable and antifouling membranes paves a new pathway for the development of sustainable membranes for osmotic power production.

Synthesis of Poly(N-vinylamide)s and Poly(vinylamine)s and Their Block Copolymers by Organotellurium-Mediated Radical Polymerization

Controlled polymerization of acyclic N-vinylamides, that is, N-methyl-N-vinylacetamide (NMVA), N-vinylacetamide (NVA), and N-vinylformamide (NVF), by organotellurium-mediated radical polymerization (TERP) is reported. The corresponding poly(N-vinylamide)s with controlled molecular weight and low dispersity (Ð<1.25) were obtained with high monomer conversion in all cases. This is the first report on the controlled polymerization of NVF. Hydrolysis of the polymers, in particular PNVF, occurred quantitatively under mild reaction conditions, giving structurally controlled poly(vinylamine)s. Block copolymers containing poly(N-vinylamide) and poly(vinylamine) segments were also synthesized in a controlled manner.

Precision design of vinyl amine and vinyl alcohol-based copolymers via cobalt-mediated radical polymerization

Controlling the amount and the distribution of vinyl amine and vinyl alcohol units within a copolymer is attractive to modulate the properties of the parent major industrial homopolymers, i.e. poly(vinyl amine) and poly(vinyl alcohol).