Synthesis and rheological investigation of self‐healable deferoxamine grafted alginate hydrogel

Deferoxamine grafted alginate (SA‐DFA) was successfully synthesized via amidation of sodium alginate with deferoxamine mesylate as determined by H‐NMR and elemental analysis. SA‐DFA with different graft yield was obtained by adjusting the ratio of sodium alginate and deferoxamine mesylate. It was found that aqueous solution of SA‐DFA could form hydrogel spontaneously due to hydrogen bonding interactions, which also endowed the SA‐DFA hydrogel with self‐healing capability. The healing efficiency of SA‐DFA hydrogels ranged from 53.64 to 90.16%. In addition, surface morphologies of SA‐DFA hydrogels before/after self‐healing process were demonstrated by SEM images. We anticipated that such self‐healable alginate hydrogel would be applied in the field of wound healing. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 856–865     

Moisture‐mediated intrinsic self‐healing of modified polyurethane urea polymers

Functional materials having the ability to self‐heal cracks or scratches after damage are of great interest for a huge scope of applications. Herein, we report a self‐healing polyurethane urea‐based material with implemented 1‐(2‐aminoethyl) imidazolidone (UDETA) as a chain terminating molecule and for hydrogen bond network formation. Both, UDETA content and moisture affected the self‐healing process. The reversible change in the materials properties was proven by detailed analyses of hardness and thermomechanical behavior in dependence of the water uptake of the samples. FT‐IR analysis revealed that water is able to act as a plasticizer interrupting hydrogen bonding interactions within the polymer network and thus, influencing glass transition temperature and hardness of the samples. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 537–548.     

Cross‐linking induced thermoresponsive hydrogel with light emitting and self‐healing property

Development of self‐healing hydrogels with thermoresponse is very important for artificial smart materials. In this article, the self‐healing hydrogels with reversible thermoresponses were designed through across‐linking‐induced thermoresponse (CIT) mechanism. The hydrogels were prepared from ketone group containing copolymer bearing tetraphenyl ethylene (TPE) and cross‐linked by naphthalene containing acylhydrazide cross‐linker. The mechanical property, light emission, self‐healing, and thermo‐response of the hydrogels were investigated intensively. With regulation of the copolymer composition, the hydrogels showed thermoresponse with the LCST varied from above to below body temperature. At the same time, the hydrogels showed self‐healing property based on the reversible characteristic of the acylhydrazone bond. The hydrogel also showed temperature‐regulated light emission behavior based on AIE property of the TPE unit. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 869–877     

Facile synthesis of self‐healing gel via magnetocaloric bottom‐ignited frontal polymerization

A series of the self‐healing gels facilely fabricated by VI (N‐vinyl imidazole) and MAH‐β‐CD (β‐cyclodextrin grafted vinyl carboxylic acid groups) via bottom‐ignited frontal polymerization (BIFP) initiated by magnetocaloric effect. Once ignited the bottom phase, the heat upward propagates to generate the “front” in the upper phase. Then, no further energy is added to maintain the reaction and the whole polymerization process experiences within minutes. In this system, the dependence of frontal velocity and temperature, along with morphology, swelling capacity, mechanical property, and self‐healing efficiency, on the preparation parameters is investigated. Interestingly, the gels show good swelling capacity in the organic solvent, comparatively almost no absorption in water. Moreover, the as‐prepared gels exhibit excellent auto‐healing properties without any external stimuli at ambient temperature. The healed sample possesses 97% recovery of its tensile strength after 8 h healing time, which relies largely on the host–guest interaction between VI and MAH‐β‐CD. The results demonstrate that FP can be utilized as an efficient and energy‐saving method to synthesize self‐healing supramolecular gels. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2585–2593     

Synthesis and healing properties of poly(arylether sulfone)–poly(alkylthioether) multiblock copolymers containing disulfide bonds

Thermoplastic elastomers composed of soft and hard segments are important elastic and processable synthetic polymers. The microphase‐separated soft domains show low glass transition temperature and possess sufficient chain mobility at room temperature. In this study, we report the synthesis and healing properties of multiblock copolymers containing disulfide bonds as dynamic covalent bonds. The multiblock copolymers composed of poly(arylether sulfone) and poly(alkylthioether) segments were synthesized by oxidative coupling polymerization of the corresponding thiol‐terminated oligomers. Atomic force microscopy phase images, differential scanning calorimetry, and dynamic mechanical analysis curves indicated the microphase‐separated morphology of the multiblock copolymer. Self‐healing properties of the polymer were evaluated by changes in the elongation at break of the cut/adhered samples. The elongation recovery increased with UV irradiation time, and the multiblock copolymer showed a 93% recovery after UV irradiation for 5 h. The healing efficiency induced by UV irradiation, determined by subtracting the recovery without UV irradiation, was calculated to be 51%. According to the UV spectra and solubility changes after UV irradiation, the main healing factor in this study was the crosslinking reactions caused by thiyl radicals generated from UV irradiation instead of disulfide exchange reactions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3545–3553     

Recent advances in the solution self‐assembly of amphiphilic “rod‐coil” copolymers

Solution self‐assembly of amphiphilic “rod‐coil” copolymers, especially linear block copolymers and graft copolymers (also referred to as polymer brushes), has attracted considerable interest, as replacing one of the blocks of a coil‐coil copolymer with a rigid segment results in distinct self‐assembly features compared with those of the coil‐coil copolymer. The unique interplay between microphase separation of the rod and coil blocks with great geometric disparities can lead to the formation of unusual morphologies that are distinctly different from those known for coil‐coil copolymers. This review presents the recent achievements in the controlled self‐assembly of rod‐coil linear block copolymers and graft copolymers in solution, focusing on copolymer systems containing conjugated polymers, liquid crystalline polymers, polypeptides, and polyisocyanates as the rod segments. The discussions concentrate on the principle of controlling over the morphology of rod‐coil copolymer assemblies, as well as their distinctive optical and optoelectronic properties or biocompatibility and stimuli‐responsiveness, which afford the assemblies great potential as functional materials particularly for optical, optoelectronic and biological applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1459–1477     

Sustainable self‐healing elastomers with thermoreversible network derived from biomass via emulsion polymerization

Motivated by the growing demand for greener and sustainable polymer systems, self‐healing elastomers were prepared by emulsion polymerization of terpene and furfural‐based monomers. Both the method and the monomers were green and sustainable. The synthesized copolymers showed molecular weights between 59,080 and 84,210 Da and glass‐transition temperature (T_g) between ?25 and ?40 °C, implying rubbery properties. A set of one‐dimensional (1D) and two‐dimensional (2D) NMR spectroscopy supported the formation of the copolymer and nuclear spin–spin coupling in the copolymer. Reactivity ratios were determined by conventional linear method. A thermoreversible network was achieved for the first time by reacting the furan‐based polymer with bismaleimide (BM) as a crosslinker, via a Diels?Alder (DA) coupling reaction. The reversible nature of the polymer network was evidenced from infrared and NMR spectroscopy. The thermoreversible character of the DA crosslinked adduct was confirmed by applying retro‐DA reaction (observed in differential scanning calorimeter [DSC] analysis) and mechanical recovery was verified by repeated heating and cooling cycles. The network polymers displayed excellent self‐healing ability, triggered by heating at 130 °C for 4–12 h, when their scratched surface was screened by microscopic visualization. The healing efficiency of the crosslinked DA‐adduct was calculated as 78%, using atomic force microscopy. This work provides a green and efficient approach to prepare new green and functional materials. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 738–751     

A “plug and play” polymer through biocomplementary hydrogen bonding

This article describes a DNA‐like polymer that exhibits the ability to self‐assemble through hydrogen bonding. We synthesized poly[1‐(4‐vinylbenzyl)thymine] (PVBT) and 9‐hexadecyladenine (A‐C16) through an atom transfer radical polymerization (ATRP) and alkylation, respectively. Biocomplementary PVBT/A‐C16 hierarchical supramolecular complexes formed in dilute DMSO solution through nucleobase recognition, that is, hydrogen bonding interactions between the thymine (T) groups of PVBT and the adenine (A) group of A‐C16; evidence for this molecular recognition was also gained from dynamic light scattering studies. ¹H NMR titration studies in CDCl₃ showed that T–A complexes formed rapidly on the NMR time scale with high association constants (up to 534 M^?1). Moreover, FTIR spectroscopic, differential scanning calorimetry, wide‐angle X‐ray diffraction, and small‐angle X‐ray scattering analyses provided further details into the nature of the self‐assembly of these systems. In the bulk state, these complexes self‐assemble into well‐ordered lamellar structures; the changing d‐spacing distance (ranging from 4.98 to 2.32 nm) at different A‐C16 loadings reveals that the molecular structures of the PVBT/A‐C16 complexes are readily tailored. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6416–6424, 2008     

Preparation and phase behavior of side‐chain cholesteric liquid‐crystalline elastomers

A series of new side‐chain cholesteric elastomers derived from cholesteryl 4‐(10‐undecylen‐1‐yloxy)‐4′‐ethoxybenzoate and phenyl 4,4′‐bis(10‐undecylen‐1‐yloxybenzoyloxy‐p‐ethoxybenzoate) was synthesized. The chemical structures of the monomers were confirmed by elemental analyses, Fourier transform infrared, and ¹H NMR and ¹³C NMR spectra. The mesomorphic properties of elastomers were investigated with differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the content of the crosslinking unit on the phase behavior of the elastomers was examined. Monomer M₁ showed a cholesteric phase, and M₂ displayed smectic and nematic phases. The elastomers containing <15 mol % of the crosslinking units revealed reversible mesomorphic phase transition, wide mesophase temperature ranges, and high thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3315–3323, 2005     

Mesomorphism,polymerization, and chirality induction in α‐cyanostilbene‐functionalized diacetylene‐assembled films: Photo‐triggered Z/E isomerization

Engineering of molecular stacking arrangement via environmental stimuli is of particular interest in stimuli‐responsive self‐assembling architectures. A novel dual photo‐functionalized diacetylene ((Z)‐CNBE‐DA) molecule was synthesized, in which photo‐responsive cyanostilbene moieties exhibited interesting Z‐E isomerization upon UV light irradiation and could be utilized to modulate mesomorphism, molecular stacking arrangement and resulting polymerization behavior. Rod‐like (Z)‐CNBE‐DA could self‐assemble into well‐defined lamellar structures and the helical polydiacetylene (PDA) chains could be formed upon irradiation with circularly polarized ultraviolet light (CPUL). However, the bent‐shaped (E)‐CNBE‐DA molecules only self‐assembled into irregular loose packing, inhibiting the formation of ordered helical PDA chains upon CPUL irradiation. In this work, we established the links between chemical structures, molecular packing engineering and photophysical properties, which would be of great fundamental value for the rational design of smart soft materials. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2458–2466     

Electrically driven self‐healing polymers based on reversible guest–host complexation of β‐cyclodextrin and ferrocene

A multifunctional ferrocene‐modified poly(glycidyl methacrylate) (PGMA‐Fc) and a difunctional β‐cyclodextrin derivative (bis‐CD) has been prepared for the construction of an electrically driven removable and self‐healing polymeric materials based on the complexation reaction between ferrocene and β‐CD groups. The chemical structures of PGMA‐Fc and bis‐CD have been characterized with Fourier transform infrared, ¹H nuclear magnetic resonance, and X‐ray photoelectron spectroscopy. The effects of electrical voltages and medium conductivity on the decrosslinking efficiency of the crosslinked PGMA‐Fc/CD polymer have been examined. The PGMA‐Fc/CD network has shown removable feature and properties for application as a reworkable crosslinked material. Moreover, the crosslinked PGMA‐Fc/CD sample has shown electrically driven self‐healing behavior. The self‐healing performance could be enhanced with wetting the sample to increase the electrical conductivity. As a result, the material could serve as a self‐healing agent for commercial painting products. Preparation and application of a novel and efficient self‐healing polymer have been demonstrated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3395–3403     

Macromolecular brushes synthesized by “grafting from” approach based on “click chemistry” and RAFT polymerization

Well‐defined macromolecular brushes with poly(N‐isopropyl acrylamide) (PNIPAM) side chains on random copolymer backbones were synthesized by “grafting from” approach based on click chemistry and reversible addition‐fragmentation chain transfer (RAFT) polymerization. To prepare macromolecular brushes, two linear random copolymers of 2‐(trimethylsilyloxy)ethyl methacrylate (HEMA‐TMS) and methyl methacrylate (MMA) (poly(MMA‐co‐HEMA‐TMS)) were synthesized by atom transfer radical polymerization and were subsequently derivated to azide‐containing polymers. Novel alkyne‐terminated RAFT chain transfer agent (CTA) was grafted to polymer backbones by copper‐catalyzed 1,3‐dipolar cycloaddition (azide‐alkyne click chemistry), and macro‐RAFT CTAs were obtained. PNIPAM side chains were prepared by RAFT polymerization. The macromolecular brushes have well‐defined structures, controlled molecular weights, and molecular weight distributions (M_w/M_n ≦ 1.23). The RAFT polymerization of NIPAM exhibited pseudo‐first‐order kinetics and a linear molecular weight dependence on monomer conversion, and no detectable termination was observed in the polymerization. The macromolecular brushes can self‐assemble into micelles in aqueous solution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 443–453, 2010     

Ring opening metathesis polymerization (ROMP) and thio‐bromo “click” chemistry approach toward the preparation of flame‐retardant polymers

This contribution describes our recent efforts geared toward the use of a general, thio‐bromo “click” reaction as a post‐polymerization method for the preparation of flame‐resistant polymeric materials. α‐bromo ester‐containing polymers could easily be prepared using ROMP and a subsequent, facile thio‐bromo click reaction was used for the installation of a phosphorus‐moiety that was shown to impart flame‐resistant/self‐extinguishing properties to these polymers. The extent of their flame resistance was then ascertained by treating paper (previously coated with polymer) to standard burn tests as well as measuring the limiting oxygen index (LOI). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 645–652     

A roadmap for poly(ethylene oxide)‐block‐poly‐ε‐caprolactone self‐assembly in water: Prediction,synthesis, and characterization

Numerical self‐consistent field (SCF) lattice computations allow a priori determination of the equilibrium morphology and size of supramolecular structures originating from the self‐assembly of neutral block copolymers in selective solvents. The self‐assembly behavior of poly(ethylene oxide)‐block‐poly‐ε‐caprolactone (PEO‐PCL) block copolymers in water was studied as a function of the block composition, resulting in equilibrium structure and size diagrams. Guided by the theoretical SCF predictions, PEO‐PCL block copolymers of various compositions have been synthesized and assembled in water. The size and morphology of the resulting structures have been characterized by small‐angle X‐ray scattering, cryogenic transmission electron microscopy, and multiangle dynamic light scattering. The experimental results are consistent with the SCF computations. These findings show that SCF is applicable to build up roadmaps for amphiphilic polymers in solution, where control over size and shape are required, which is relevant, for instance, when designing spherical micelles for drug delivery systems © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 330–339     

Fine tuning the assembly and gel behaviors of PEGylated polypeptide conjugates by the copolymerization of l‐alanine and γ‐benzyl‐l‐glutamate N‐carboxyanhydrides

Tuning the secondary structure of polypeptide is an effective strategy to modulate the assembly behaviors of polypeptide‐based copolymers. In this study, ring‐opening polymerization of l ‐alanine (Ala) and γ‐benzyl‐l ‐glutamate (BLG) N‐carboxyanhydrides was adopted using mPEG‐NH₂ as the initiator to prepare mPEG‐poly(l ‐alanine‐co‐γ‐benzyl‐l ‐glutamate) (PEAB) copolymers with various Ala to BLG ratios. ¹H NMR spectra and GPC test confirmed their well‐defined chemical structures. FT‐IR spectra indicated that at the powder state, all copolymers adopted both β‐sheet and α‐helical conformations. With the content of PBLG increased, the crystallization temperature and melting points of PEAB copolymers first rose then fell indicated by DSC curves. The self‐assembly of PEAB copolymers in dilute aqueous solution studied by DLS, TEM and circular dichroism spectra showed that PEAB copolymers self‐assembled into nanostructures with diverse morphologies and sizes due to distinct polypeptide conformations. Rheological analysis indicated that the alteration of the polypeptide composition can effectively modulate the modulus of PEAB assemblies in concentrated solutions. In all, copolymerization of two hydrophobic amino acid N‐carboxyanhydrides into the polypeptide block maybe an effective approach for modulating the assembly properties of PEGylated polypeptide. Besides, nanosilver‐encapsulated PEA or PEAB hydrogel showed promising antibacterial effect against Staphylococcus aureus and Bacillus subtillis. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1512–1523     

A facile and controllable synthesis of dual‐crosslinked elastomers based on linear bifunctional polydimethylsiloxane oligomers

Dual‐crosslinked supramolecular elastomers with the hybrid network consisting of hydrogen bonds and covalent bonds combine the reversibility of hydrogen bond and mechanical properties of covalent crosslinking network. In this article, isocyanate mixture is used as curing agent to prepare dual‐crosslinked elastomer based on bifunctional polydimethylsiloxane under mild condition. This method can effectively build up a hybrid network with the designed structure. A series of elastomers with same hydrogen bond density and variable covalent crosslinking degree are obtained. Swelling measurements and ¹H‐NMR spectra confirm the feasibility and controllability of curing method, the increasing of bifunctional isocyanate give rise to higher covalent crosslinking degree, improving the solvent resistance. The studies on viscoelastic property show that the introduction of an irreversible covalent crosslinking network stabilize the hybrid network, restrain the chain movement. The mechanical and self‐healing property studies reveal that the covalent crosslink significantly reinforce the whole network, while the reparable strength seems to mainly depend on the hydrogen bond density. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3760–3768     

Synthesis of self‐healing supramolecular rubbers from fatty acid derivatives,diethylene triamine,and urea

We describe the synthesis of supramolecular self‐healing elastomers from vegetable oil fatty acid derivatives, diethylene triamine, and urea. Our strategy to obtain materials that are self‐healing but do not flow relies on the use of a wide molecular distribution of randomly branched oligomers equipped with self‐complementary and complementary hydrogen bonding groups. We prepared such oligomers with a two steps procedure. In the first step, diethylene triamine was condensed with dimer acids. In the second step, the oligomers obtained were allowed to react with urea. The molecules were characterized by NMR and IR spectroscopies and Monte‐Carlo simulations were used to analyze the molecular size distribution. The sensitivity to small variations of the experimental conditions has been examined and the robustness of the synthetic procedure optimized. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7925–7936, 2008     

PLMA‐b‐POEGMA amphiphilic block copolymers: Synthesis and self‐assembly in aqueous media

The synthesis and self‐assembly properties in aqueous solutions of novel amphiphilic block copolymers composed of one hydrophobic poly (lauryl methacrylate), (PLMA) block and one hydrophilic poly (oligo ethylene glycol methacrylate) (POEGMA) block are reported. The block copolymers were prepared by RAFT polymerization and were molecularly characterized by size exclusion chromatography, NMR and FT‐IR spectroscopy, and DSC. The PLMA‐b‐POEGMA amphiphilic block copolymers self‐assemble in nanosized complex nanostructures resembling compound micelles when inserted in aqueous media, as supported by light scattering and TEM measurements. The encapsulation and release of the model, hydrophobic, nonsteroidal anti‐inflammatory drug indomethacin in the polymeric micelles is also investigated. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 155–163     

Aqueous self‐assembly of pullulan‐b‐poly(2‐ethyl‐2‐oxazoline) double hydrophilic block copolymers

The self‐assembly of a novel double hydrophilic block copolymer in water without the application of external triggers is described, namely pullulan‐b‐poly(2‐ethyl‐2‐oxazoline) (Pull‐b‐PEtOx). The biomacromolecules, Pull (8–38 kg mol^?1), is modified and conjugated to biocompatible PEtOx (22 kg mol^?1) via modular conjugation. Moreover, the molecular weight of the Pull blocks are varied to investigate the effect of molecular weight on the self‐assembly behavior. Spherical particles with sizes between 300 and 500 nm are formed in diluted aqueous solution (0.1–1.0 wt %) as observed via dynamic light scattering and static light scattering. Additionally, cryo scanning electron microscopy and laser scanning confocal microscopy are performed to support the finding from light scattering. The block ratio study shows an optimum ratio of Pull and PEtOx of 0.4/0.6 for self‐assembly in water in the concentration range of 0.1–1.0 wt %. At higher concentrations of 20 wt %, vesicular structures with sizes above 1 µm can be observed via optical microscopy. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3757–3766     

“On–off” switching of dynamically controllable self‐assembly formation of double‐responsive block copolymers with tunable LCSTs

We report here a reversible self‐assembly formation system using block copolymers with thermo‐tunable properties. A series of double‐responsive block copolymers, poly(N‐isopropylacrylamide (NIPAAm))‐block‐poly(NIPAAm‐co‐N‐(isobutoxymethyl)acrylamide (BMAAm)) with two lower critical solution temperatures were synthesized by one‐pot atom transfer radical polymerization via sequential monomer addition. When dissolved in aqueous solution at room temperature, the block copolymers remained unimeric. Upon heating above room temperature, the block copolymers self‐assembled into micellar structures. The micelle formation temperature and the resulting diameter were controlled by varying the BMAAm content. ¹H Nuclear Magnetic Resonance, dynamic light scattering, field‐emission scanning electron microscopy, and fluorescence spectra revealed the presence of a monodisperse nanoassembly, and demonstrated the assembly formation/inversion process was fully reversible. Moreover, a model hydrophobic molecule, pyrene, was successfully loaded into the micelle core by including pyrene in the original polymer solution. Further heating resulted in mesoscopic micelle aggregation and precipitation. This dual micelle and aggregation system will find utility in drug delivery applications as a thermal trigger permits both aqueous loading of hydrophobic drugs and their subsequent release. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010