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Iron-containing poly(ionic liquid) membranes were prepared by Cu(0)-mediated reversible deactivation radical polymerization, which was achieved to catalyze a heterogeneous Fenton reaction and realize self-cleaning of the membrane surface.

A claw-type Schiff base, tris[N-(2-pyridylmethyl)-2-iminoethyl]amine (Py3Tren), is used as an active ligand for photoinduced atom transfer radical polymerization (Photo-ATRP). CuBr2/Py3Tren was employed as a catalyst for Photo-ATRP of methyl methacrylate (MMA) under the irradiation of ultraviolet or visible light. Well-defined poly(MMA) could be synthesized with high chain-end functionality confirmed by in situ chain extension. Temporal control of Photo-ATRP was successfully demonstrated by switching the light on and off. The polymerization mechanism was finally discussed through UV/vis spectroscopy and electrospray ionization mass spectrometry (ESI-MS) experiments.

Mechanically robust polyurethanes and polyureas with excellent healing and recycling capacities have an extended service life, and can reduce raw material consumption and environmental pollution. In this work, healable, recyclable and mechanically super-strong poly(urea-urethane)s (PUUs) are conveniently fabricated via cross-linking isocyanate-terminated poly(tetramethylene ether glycol) (PTMEG) with nitrogen-coordinated boroxines (NCBs). The tripodal NCBs generate three-dimensionally cross-linked PUUs (denoted as NCB-PUUs) with a high cross-linking density. Meanwhile, hydrogen bonds and phase-separated PTMEG segments can serve as physical cross-linkers to further strengthen NCB-PUUs. As a result, the NCB-PUUs exhibit a tensile strength of ∼47 MPa and a toughness of ∼190 MJ m−3. Because of the high reversibility of NCBs and hydrogen bonds, the NCB-PUUs are capable of efficiently healing and recycling at room temperature with the assistance of ethanol or a water/ethanol mixture to restore their original mechanical strength. NCB-PUUs can be conveniently deposited on solid surfaces by dip-coating and spraying methods to serve as protecting coatings. The NCB-PUU coatings have firm adhesion on solid surfaces and can be doped with organic dyes to display diverse colors. More importantly, the NCB-PUU coatings can heal deep and wide cuts and scratches for multiple times in a given region.

Degradable polymers that play an increasingly important role in the development of sustainable society are highly expected to exhibit not only high mechanical strength, but also superior toughness. Herein, degradable polyurethane thermosets with high mechanical strength and toughness are synthesized by cross-linking isocyanate-terminated prepolymers with boric acids. The incorporation of triple boron–urethane bonds derived from the coupling between hydroxyl groups in boric acids and isocyanate groups in the prepolymers into polyurethanes brings about a significant enhancement in the mechanical properties of the polyurethanes. Typically, PTMEG-HDI-BA1.5 exhibits optimal mechanical performances with an ultimate strength of ∼53.9 MPa, tensile strain of ∼1865%, and toughness of ∼390 MJ m−3. The toughness of poly(boron–urethanes) is even better than that of spider dragline silk (∼180 MJ m−3). The labile nature of the boron–urethanes enables the polyurethane thermosets to be rapidly degraded under mild acid conditions. The PTMEG-HDI-BA1.5 samples can be entirely decomposed in 0.1 M HCl/THF solution in 3 h at room temperature. Meanwhile, the degraded polyurethane thermosets can be further recycled into linear PU oligomers. Based on the above results, a new approach to fabricate degradable polymeric materials with simultaneously high mechanical strength and toughness is provided in this study.

It is a long-term pursuit, and also, a challenge to significantly improve the mechanical strength of thermoplastic polymers using readily dispersed polymers as nanofillers. In this study, we demons...

Nondegradable PEGylated protein drugs are known to cause accumulation in the tissue and accelerated blood clearance effect, which inspire people to develop alternative polymers such as polyesters for bioconjugation. However, the hydrophobicity and slow degradation rate of polyesters remain as challenges for typical therapeutic applications. Here, we report the facile synthesis of biodegradable protein–poly(e-caprolactone) conjugates via enzymatic ring opening polymerization (eROP). Candida antarctica lipase B (CALB)–poly(N-hydroxyethyl acrylamide) conjugates with pendent hydroxyl groups were utilized as initiators and catalysts simultaneously for the eROP of e-caprolactone to form amphiphilic graft copolymers. The enzymatic degradation of ester-containing polymers in the conjugates could be significantly accelerated by lipase, leading to total degradation in several days.

Protein-loaded hydrogels were synthesized via biocatalytic atom transfer radical polymerization (ATRP) for the first time. Laccase from Trametes versicolor acted as the ATRPase for the enzymatic polymerizations and was in situ loaded into the porous network of poly(ethylene glycol)-based hydrogels. The use of additional ligands such as tris(2-(dimethylamino)ethyl)amine could significantly increase the polymerization conversion, allowing the polymerizations to occur at ambient or even lower temperature. The rheology and water uptake ratio of hydrogels could be tuned by using different cross-linkers. Immobilized enzymes in the hydrogels have shown decreased yet considerable activity compared with pristine laccase. The hydrogels could be facilely recovered and reused up to six times with no significant decrease in enzyme activity. Such hydrogels were successfully used for the oxidative polymerization of hydroquinone and may find potential applications in protein delivery and water treatment.

The use of a tripodal heptadentate Schiff base, tris[N-(2-pyridylmethyl)-2-iminoethyl]amine (Py3Tren), as an active ligand for atom transfer radical polymerization (ATRP) is reported. The coordination between Py3Tren and CuBr2 in solution is investigated by electrospray ionization mass spectrometry, which reveals the generation of a tripod claw-shaped complex by using equimolar quantities of CuBr2 and Py3Tren. Electrochemical studies of CuBr2/Py3Tren complexes demonstrate more negative redox potentials and higher activities compared with those of bidentate CuBr2/N-ethyl-2-pyridylmethanimine (PyEthyl) complexes. Subsequently, CuBr/Py3Tren is employed as a catalyst for the normal ATRP of methyl methacrylate (MMA). Well-defined poly(MMA) with controlled molecular weight and narrow polydispersity could be synthesized with high conversions and fast rates even at ambient temperature (30 °C). Activators regenerated by electron transfer (ARGET) ATRP and supplemental activators and reducing agents (SARA) ATRP of acrylate monomers using Py3Tren as the ligand are also performed to reduce the amounts of metal catalysts for polymerizations.

A facile synthetic route is reported toward sugar-containing pyridinium-based poly(ionic liquid)s (PILs). Reversible deactivation radical polymerization of 4-vinyl pyridine could generate a well-defined poly(4-vinyl pyridine) in a self-generating biphasic system. Subsequent quaternization and anion exchange reaction could yield a library of functional PILs with pendent sugar units and varied anions.

Polymerization-induced self-assembly (PISA) has evolved as a facile pathway for the in situ formation of polymeric nanomaterials with unique morphologies. However, aqueous PISA by atom transfer radical polymerization (ATRP) for the generation of protein-based nanoassemblies is still challenging. In this research, Candida antarctica lipase B (CALB) is modified as the macroinitiator for Cu(0)-mediated reversible deactivation radical polymerization (Cu(0)-RDRP) of both hydrophilic and hydrophobic monomers in water or water/methanol mixtures. Different acrylamides and acrylates are successfully polymerized in the presence of lipase-based macroinitiators under mild reaction conditions and it is found that the lipase-catalyzed hydrolysis of ester bonds from poly(acrylates) is very significant. The PISA of lipase–hydrophobic polymer conjugates could directly generate spherical nanoparticles in aqueous solution without further processing. Activity tests further demonstrate preservation or even a significant increase of the enzymatic activity for the conjugates, indicating the potential application of aqueous PISA in protein delivery and enzyme immobilization.

Supramolecular assemblies with reversible boronate ester linkages are facilely prepared via self-assembly between cyclodextrin-centered glycoclusters and 4,4'-(1,2-diphenylethene-1,2-diyl)bis(1,4-phenylene)diboronic acid (TPEDB). Such sphere-like assemblies have shown a typical aggregation-induced emission (AIE) effect and could act as fluorescent probes for the sensitive detection of phenols in water.

Covalent coupling of hydrophobic polymers to the exterior of hydrophilic proteins would mediate unique macroscopic assembly of bioconjugates to generate amphiphilic superstructures as novel nanoreactors or biocompatible drug delivery systems. The main objective of this study was to develop a novel strategy for the synthesis of protein-polymer giant amphiphiles by the combination of copper-mediated living radical polymerization and azide-alkyne cycloaddition reaction (CuAAC). Azide-functionalized succinimidyl ester was first synthesized for the facile introduction of azide groups to proteins such as albumin from bovine serum (BSA) and laccase from Trametes versicolor. Alkyne-terminal polymers with varied hydrophobicity were synthesized by using commercial copper wire as the activators from a trimethylsilyl protected alkyne-functionalized initiator in DMSO under ambient temperature. The conjugation of alkyne-functionalized polymers to the azide-functionalized laccase could be conducted even without additional copper catalyst, which indicated a successful self-catalyzed CuAAC reaction. The synthesized amphiphiles were found to aggregate into spherical nanoparticles in water and showed strong relevance to the hydrophobicity of coupled polymers. The giant amphiphiles showed decreased enzyme activity yet better stability during storage after chemical modification and self-assembly. These findings will deepen our understanding on protein folding, macroscopic self-assembly, and support potential applications in bionanoreactor, enzyme immobilization, and water purification.

It is challenging to regenerate enzyme carriers when covalently immobilized enzymes suffered from inactivation during continuous operations. Hence, it is urgent to develop a facile strategy to immobilize enzymes reversibly. Herein, the non-covalent interaction between protein and carbohydrate was used to adsorb and desorb enzymes reversibly. Laccase was immobilized onto glycopolymer microspheres via protein-carbohydrate interaction using lectins as the intermediates. The enzyme loading and immobilization yield were up to 49 mg/g and 77.1% with highly expressed activity of 107.9 U/mg. The immobilized laccase exhibited enhanced pH stability and high activity in catalyzing the biodegradation of paracetamol. During ten successive recoveries, the immobilized laccases could be recycled while maintaining relatively high enzyme activity. The glycopolymer microspheres could be efficiently regenerated by elution with an aqueous solution of mannose or acid for further enzyme immobilization. This glycopolymer microspheres has excellent potential to act as reusable carriers for the non-covalent immobilization of different enzymes.

Excess boron in water could result in a critical hazard to plants and humans. Traditional treatment approaches cannot efficiently remove boron from water, especially during seawater desalination using reverse osmosis technology. Achieving satisfactory adsorption capacity and rate for boron remains an unmet goal for decades. Herein, we report cellulose-derived polyols as high-performance adsorbents that can rapidly remove boron and organic pollutants from water. Cellulose-derived polyols were synthesized from saccharides and cellulose via controlled radical polymerization and click reaction. Remarkably, CA@NMDG can adsorb boron with an astonishing capacity of ~34 mg g-1 in 10 min, which surpasses all those cellulose-based materials reported thus far, meanwhile, much faster than those of commercial adsorption resin. Moreover, cellulose-derived polyols also showed high removal efficiencies (70–98% in several minutes) toward certain organic pollutants, including Congo red and Reactive Blue 19. The water-insoluble characteristic of cellulose-derived polyols is advantageous to be separated from the treated sewage after adsorption for reuse. This work provides a novel insight into the fabrication of safe, fast, and high-capacity cellulose adsorbents for water purification.

Novel self-cleaning catalytic membranes are prepared for water treatment via an integration of heterogeneous Fenton and membrane process. Polysulfone (PSF) based functional copolymers with pendant ferrocene groups are facilely synthesized via a combination of controlled radical polymerization and ester coupling reaction. Different catalytic membranes with tuned surface hydrophilicity are then prepared through non-solvent phase inversion method based on functional ferrocene- and hydroxyl-containing PSF. These membranes have demonstrated high activity in catalyzing Fenton-type reactions, which also lead to outstanding antifouling performance for the membrane. Finally, the catalytic membranes are successfully used for treatment of waste water containing different dyes. The proposed strategy in this work may provide worthy guidance to catalytic membranes, which is promising for water purification through simultaneous Fenton reaction and membrane separation.

It remains a challenge to fabricate sacrificial films that are stable in most of solvents and can be readily decomposed on demand. Here we report the fabrication of a near-infrared (NIR) light decomposable sacrificial film by layer-by-layer (LbL) assembly of UV-light-decomposable poly((4-(2-bromoethoxy)-5-methoxy-2-nitrobenzyl acrylate) triethylammonium bromide) (PNBA-TEA), poly(sodium 4-styrene-sulfonate) (PSS), branched polyethyleimine (bPEI), and lanthanide-doped upconversion nanoparticles (UCNPs). The [(PNBA-TEA/PSS)*2/(bPEI/UCNPs)*3]*2 films are stable in deposition solutions of various materials and decompose upon NIR light irradiation. In the [(PNBA-TEA/PSS)*2/(bPEI/UCNPs)*3]*2 films, UCNPs can convert NIR light into UV light, which can decompose PNBA-TEA. After immersing the NIR light-irradiated [(PNBA-TEA/PSS)*2/(bPEI/UCNPs)*3]*2 films in 0.1 M aqueous NaHCO3 solution, the disintegration of the entire films occurs because of the repulsive force between the negatively charged photoproduct of PNBA-TEA and PSS. LbL-assembled (PAH/PAA)*50 films deposited on top of the NIR-light-decomposable [(PNBA-TEA/PSS)*2/(bPEI/UCNPs)*3]*2 films can be conveniently released to produce large-area and defect-free (PAH/PAA)*50 free-standing films after NIR light irradiation and subsequent immersion in 0.1 M aqueous NaHCO3 solution. Because of the satisfactory stability and on-demand decomposable property, the [(PNBA-TEA/PSS)*2/(bPEI/UCNPs)*3]*2 films are promising as sacrificial layers for the fabrication of various free-standing films.

The fabrication of mechanically robust polymeric materials capable of self-healing and recycling remains challenging because the mobility of polymer chains in such polymers is very limited. In this work, mechanically robust supramolecular thermosets capable of healing physical damages and recycling under mild conditions are fabricated by trimerization of bi-( ortho-aminomethyl-phenylboronic acid)- and tri-( ortho-aminomethyl-phenylboronic acid)-terminated poly(propylene glycol) oligomers (denoted as Bi-PBA-PPG and Tri-PBA-PPG, respectively). The resultant supramolecular thermosets are cross-linked by dynamic covalent bonds of nitrogen-coordinated boroxines. The mechanical properties of the supramolecular thermosets can be systematically tailored by varying the ratios between Tri-PBA-PPG and Bi-PBA-PPG, which changes the cross-linking density of nitrogen-coordinated boroxines and the topology of the supramolecular thermosets. The mechanically strongest supramolecular thermosets with a molar ratio of Tri-PBA-PPG to Bi-PBA-PPG being 1:2 have a glass transition temperature of ∼36 °C, a tensile strength of ∼31.96 MPa, and a Young's modulus of ∼298.5 MPa. The high reversibility of nitrogen-coordinated boroxines and the flexibility of poly(propylene glycol) chains enable the supramolecular thermosets with the strongest mechanical strength to be highly efficiently healed at 55 °C and recycled under a pressure of 4 MPa at 60 °C to regain their original mechanical strength and integrity.