Burn, trauma, and various medical conditions including bacterial infection, diabetes complication, and surgery could lead to an acute cutaneous wound and scar formation. Application of tissue glues instead of sutures could minimize the additional trauma and scar formation. Despite the countless efforts devoted to the development of high-strength tissue glues, little attention has been paid to their influence on the scar formation. Here, we report the development of a new tissue glue with excellent biocompatibility and tunable degradability for scarless wound closure. A series of catechol-containing poly(amidoamine) (CPAA) polymers were synthesized via the one-step Michael addition of dopamine and bisacrylamide. The tertiary amino group in the polymer backbone was used to introduce a zwitterionic sulfobetaine group by one-step ring-opening polymerization. The introduction of the zwitterionic sulfobetaine group could easily tune the hydrophilicity and the degradability of CPAA without influencing the density of the catechol group in the polymer. Lap-shear tests on the porcine skin demonstrated a high adhesion strength of 7 kPa at 1 h, rising to 24 kPa by 12 h. Addition of silica nanoparticles could further enhance the adhesion strength by 50%. In vivo studies further confirmed that the CPAA tissue glue could effectively accelerate the healing process of incisional wounds on the back of Sprague Dawley rats compared with suture and reduce the scar formation.Topics: Drug discovery and Drug delivery systems; Environmental biology; Environmental biology; Nanoparticles; Polyesters; Polymerization kinetics; Polyoxyalkylenes;

Sulfur-containing polymers have renewed widespread attention due to their fascinating properties like high refractive index and semiconducting character. However, examples of direct polymerization involving elemental sulfur are limited. Herein, a new strategy to prepare polythioamide (PTA) by direct polymerization of aliphatic primary diamines in the presence of sulfur is reported. The polymerization of p-xylylenediamine (1) and sulfur at 110 °C in N-methyl-2-pyrrolidinone afforded PTA1 of high Mw and high yield when the feed ratio of [1]:[S] ranged from 1:2 to 1:3. 1H NMR and 13C NMR spectra confirmed that there are three kinds of structural units among the PTA1 chains. Moreover, different diamines including m-xylylenediamine (2), 1,6-hexanediamine (3), ethylenediamine (4), and 1,4-cyclohexanediamine (5) were copolymerized with 1 in the presence of sulfur to obtain PTA copolymers. With an increase in 5 content, the copolymer PTA1/5 with an alternating sequence in the range of 56%–94% was prepared. Solubility and thermal properties of homopolymers and copolymers were studied. Meanwhile, the copolymers PTA1/3 and PTA1/5 possessed a high refractive index as high as 1.7.

Excellent mechanical properties and remarkable self-healing ability are difficult to unify in one hydrogel. We integrated acylhydrazone bonds and Pluronic F127 (PF127) micelle cross-linking, as two kinds of dynamic cross-links, in one system and developed hydrogels with superior stretchability, high toughness, and good self-healing ability. The hydrogel could stretch up to 117 times its initial length and self-heal approximately 85% of its initial strength within 24 h. The toughness of the hydrogel, indexed by the work of extension, W, reached 14.1 MJ m–3. Energy dissipation occurred from the simultaneous decomposition of the PF127 micelles and chain sliding facilitated by the reconfiguration of the acylhydrazone bonds. This unique combination and dynamics led to pronounced hysteresis in the loading–unloading cycles, as well as good recovery and self-healing of the hydrogel. Dynamic cross-linking of the covalent acylhydrazone bonds was comparable to those of physical interactions, such as coordination and ionic bonding.

Design and fabrication of the micro/nanostructures of the network units is a critical issue for porous nanonetwork structured materials. Significant progress has been attained in construction of the network units with zero-dimensional spherical shapes. However, owing to the limitations of synthetic methods, construction of porous building blocks in one dimension featuring high aspect ratios for porous nanonetwork structured polymer (PNSP) remains largely unexplored. Here we present the successful design and preparation of PNSP with a novel type of one-dimensional network unit, i.e., microporous heterogeneous nanowire. Well-defined core-shell polymer nanoobjects prepared from a gelable block copolymer, poly(3-(triethoxysilyl)propyl methacrylate)-block-polystyrene are employed as building blocks, and facilely transformed into PNSP via hypercrosslinking of polystyrene shell. The as-prepared PNSP exhibits unique three-dimensional hierarchical nanonetwork morphologies with large surface area. These findings could provide a new avenue for fabrication of unique well-defined PNSP, and thus generate valuable breakthroughs in many applications.

•Self-healing PDMS elastomers based on acylhydrazone groups were prepared.•A reversible transition was observed around 80 °C.•Role of H-bonds on self-healing properties was elucidated.A PDMS elastomer based on acylhydrazone groups with both acid- and heat-assisted self-healing properties was successfully prepared from tetra-acylhydrazine-terminated PDMS and terephthalaldehyde through solution casting. The good healing performance was obtained with catalytic acetic acid for 24 h at 25 °C or by annealing at 120 °C for 2 h. The elastomer exhibited a reversible transition near 80 °C observed by rheological measurements and variable-temperature FTIR, which corresponded to the dissociation and reconstruction of hydrogen bonds between acylhydrazone groups. Since the non-equimolar sample presented similar behaviors with the equimolar sample, it verifies that the reversible dissociation/reformation of hydrogen bonds dominates the heat-assisted self-healing process. This finding will enable better understanding of the contribution of hydrogen bonding interactions in acylhydrazone self-healing systems, thus promoting the development of self-healing bulk materials based on acylhydrazone groups.Download high-res image (321KB)Download full-size image

Controlled delivery of protein would find diverse therapeutic applications. Formulation of protein nanoparticles by polyelectrolyte complexation between the protein and a natural polymer such as chitosan (CS) is a popular approach. However, the current method of batch-mode mixing faces significant challenges in scaling up while maintaining size control, high uniformity, and high encapsulation efficiency. Here we report a new method, termed flash nanocomplexation (FNC), to fabricate insulin nanoparticles by infusing aqueous solutions of CS, tripolyphosphate (TPP), and insulin under rapid mixing condition (Re > 1600) in a multi-inlet vortex mixer. In comparison with the bulk-mixing method, the optimized FNC process produces CS/TPP/insulin nanoparticles with a smaller size (down to 45 nm) and narrower size distribution, higher encapsulation efficiency (up to 90%), and pH-dependent nanoparticle dissolution and insulin release. The CS/TPP/insulin nanoparticles can be lyophilized and reconstituted without loss of activity, and produced at a throughput of 5.1 g h−1 when a flow rate of 50 mL min−1 is used. Evaluated in a Type I diabetes rat model, the smaller nanoparticles (45 nm and 115 nm) control the blood glucose level through oral administration more effectively than the larger particles (240 nm). This efficient, reproducible and continuous FNC technique is amenable to scale-up in order to address the critical barrier of manufacturing for the translation of protein nanoparticles.

Three kinds of naphthalene-containing diamines with –H, –CH3 or –CH(CH3)2 substituents at the ortho-positions of the aniline ring including 4,4′-(naphthalen-1-ylmethylene)dianiline (BAN-1), 4,4′-(naphthalen-1-ylmethylene)bis(2,6-dimethylaniline) (BAN-2) and 4,4′-(naphthalen-1-ylmethylene)bis(2,6-diisopropylaniline) (BAN-3) were synthesized via a simple one-step electrophilic substitution reaction. These diamines were then reacted with three commercial dianhydrides, via chemical imidization under microwave irradiation, to obtain nine types of polyimide (PI). It was found that the introduction of alkyl side groups can improve the solubility and optical transparency of PIs. Moreover, compared with BAN-2 based PIs containing –CH3 groups, BAN-3 based PIs containing –CH(CH3)2 groups exhibited better solubility and optical transparency (transmittances at 450 nm of over 86%). Meanwhile, due to the presence of the rigid naphthalene side groups, all the PIs possessed high thermal stability with a glass transition temperature (Tg) of over 290 °C and a decomposition temperature at 5% weight loss of over 510 °C under nitrogen. Furthermore, the Tg of PI-2B composed of BAN-2 and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was found to be as high as 387 °C, which is comparable to that of the commercial and conventional PI material (Kapton®, Tg = 390 °C).

This article demonstrates a new post-modification method to synthesize well-defined brominated polymers based on the bromination of hydroxyl-containing polymers. Bromination conditions for poly(2-hydroxylethyl methacrylate) (PHEMA) with diethylaminodifluorosulfinium tetrafluoroborate (XtalFluor-E), including solvents, bromine sources, additives, feeding ratios and reaction times were studied in detail. It was found that all –OH groups of PHEMA were quantitatively transformed to –Br groups and that the product maintained a narrow molecular weight distribution with a combination of XtalFluor-E, tetrabutylammonium bromide (TBAB) and 1,8-diazabicyclo(5.4.0)undec-7-ene( DBU) in dichloromethane for 24 h, at a feed ratio of [OH] : [XtalFluor-E] : [TBAB] : [DBU] = 1 : 5 : 5 : 5. Thus, well-defined poly(2-bromoethyl methacrylate) (PBEMA) and its copolymer poly(BEMA-co-MMA) were readily prepared via post-modification of the corresponding PHEMA and poly(HEMA-co-MMA) copolymer at room temperature followed by a simple precipitation procedure. This methodology was additionally applied to obtain α,ω-dibromo and mono-bromo terminated poly(ethylene glycol)s (PEGs) from the corresponding hydroxyl-capped PEGs. The facile and efficient bromination of hydroxyl-containing polymers has the potential to be a universal methodology for the synthesis of a diverse range of brominated polymers.

•Hexagonally perforated lamellae (HPL) by bulk microphase separation of PtBMA-b-PS diblock copolymer.•Perforated nanosheets by dispersing PL bulk sample in methanol.•Water-dispersed perforated nanosheets by hydrolysis of PtBMA component.•Confirming the PL structure as a transition phase between lamellar and cylindrical phase.•Potential application as unique porous materials and ultrafiltration membrane, etc.Perforated lamellar (PL) microphase structure of block copolymers in the bulk is rarely observed. Herein, formation of the PL structure from simple block copolymer, poly(tert-butyl methacrylate)-block-polystyrene (PtBMA-b-PS) prepared by reversible addition–fragmentation chain transfer (RAFT) mediated radical polymerization, is reported. The PL phase consists of alternating layers of PS and PtBMA microdomains, among which the PS layers contain ordered cylindrical domains of PtBMA. It is confirmed that the PL phase is located between the cylindrical phase and lamellar phase. In methanol, the microphase-separated sample is readily split into individual core/shell nanosheets with perforated glassy PS core. The PtBMA domains are densely attached both as the shells along PS sheets and as passages with a hexagonal pattern. The passage has a diameter of ca. 12 nm and an average periodic distance of 31 nm.

A general approach to fabricate a series of silica nanoobjects with sheet-like, tubular and hollow spherical shapes was reported. These silica nanoobjects were prepared by using water-dispersed diblock copolymer nanoobjects with glassy polystyrene cores and densely grafted poly(2-(dimethylamino)ethylmethacrylate) (PDMAEMA) shells as templates as well as catalysts. A sol–gel reaction of tetramethoxysilane (TMOS) was subsequently induced by PDMAEMA shells of shaped nanoobjects in water dispersions at near-neutral pH and under ambient conditions, and thus the shaped polymer@silica hybrids with a high silica content (around 70 wt% silica in hybrids) were obtained. Then silica nanoobjects of three different dimensions were further prepared by calcination at 650 °C to remove the organic components. The spherical and cylindrical silicas have a hollow structure. Formation of diblock copolymers, polymer nanoobjects, polymer@silica hybrids, and silica nanoobjects was characterized by 1H NMR spectroscopy, size exclusion chromatography (SEC), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), solid state 29Si CPMAS NMR analysis, N2 adsorption–desorption measurements, and Fourier-transform infrared spectroscopy (FT-IR). This methodology could be a general approach to fabricate various inorganic nanoparticles with different geometric shapes.

A macroscopic organohydrogel hybrid was prepared by fast adhesion between the hydrogel and organogel which often repel each other. The two original gels were prepared by condensation of two poly(ethylene glycol) (PEG) gelators in anisole and water, respectively. Reversible acylhydrazone bonds formed in the condensation act as linking points of the polymer networks in the gels. When the two gels were brought into contact, a robust hybridized gel was obtained in 10 min. An emulsion layer formed at the interface between the two gels and dynamic chemistry of acylhydrazone bonding are key factors in rapid adhesion of the two inherently different gels. We hope this finding will enable the development of intelligent soft objects whose macroscopic water and oil phases contain different functional components.

Polymer-tethered nanoparticles with different geometric shapes are very useful fillers of polymer nanocomposites. Herein, a universal approach for the fabrication of such nanoparticles with precisely controlled shape and composition is reported. By microphase separation of poly(3-(triethoxysilyl)propyl methacrylate)-block-polystyrene (PTEPM-b-PS) in the presence of oligomers, o-TEPM (oT) and/or o-S (oS), followed by cross-linking and dispersion in PS solvent, precisely tailored PS-grafted nanoparticles were prepared. These particles include those with varied shapes but identical PS shells, particles with varied core sizes but the same PS shell, and particles with fixed shapes but varied PS shells. These particles are ideal model nanofillers to study the dynamics and reinforced mechanism of polymer nanocomposites.

Novel biobased polyimides (PIs) with good optical transparency and comprehensive properties were synthesized from isomannide-derived diamine and dianhydride monomers. Three kinds of diamines including 2,5-diamino-2,5-dideoxy-1,4:3,6-dianhydroiditol (M1), 1,4:3,6-dianhydro-2,5-di-O-(4-aminophenyl)-D-mannitol (M2), and 1,4:3,6-dianhydro-2,5-di-O-(2-trifluoromethyl-4-aminophenyl)-D-mannitol (M3), as well as 1,4:3,6-dianhydro-2,5-di-O-(3,4-dicarboxyphenyl)-D-mannitol dianhydride (M4), were prepared based on isomannide. These diamines M1–M3 were reacted with M4 and a commercial dianhydride, 4,4′-oxydiphthalic anhydride (ODPA), via a two-step polymerization method, respectively, to yield a series of biobased PI films, PI-1 to PI-6. The resultant PIs had a high content of biomass up to 48 wt%, and they can be readily soluble in various non-proton polar solvents at room temperature. Most of the biobased PIs showed good optical transparency (transmittances at 450 nm over than 80%), along with a cut-off wavelength of 343–364 nm. Furthermore, due to the existence of rigid alicyclic isomannide among the polymeric backbone, biobased PIs maintained fairly high thermal stability with a glass transition temperature of 227–264 °C, and temperature at 5% weight loss over 400 °C in nitrogen. Meanwhile, these PIs exhibited outstanding mechanical properties with tensile strengths greater than 90 MPa and elongation at break higher than 6.0%. It was also found that the biobased PI series with alicyclic M1 possessed higher thermal stability than PIs with semi-aromatic diamines M2 and M3. Thereof, the introduction of biomass building blocks into PIs can offer a great opportunity to develop new sustainable materials with high performance for microelectronic and optoelectronic applications.

A general approach to fabricate a series of silica nanoobjects with sheet-like, tubular and hollow spherical shapes was reported. These silica nanoobjects were prepared by using water-dispersed diblock copolymer nanoobjects with glassy polystyrene cores and densely grafted poly(2-(dimethylamino)ethylmethacrylate) (PDMAEMA) shells as templates as well as catalysts. A sol–gel reaction of tetramethoxysilane (TMOS) was subsequently induced by PDMAEMA shells of shaped nanoobjects in water dispersions at near-neutral pH and under ambient conditions, and thus the shaped polymer@silica hybrids with a high silica content (around 70 wt% silica in hybrids) were obtained. Then silica nanoobjects of three different dimensions were further prepared by calcination at 650 °C to remove the organic components. The spherical and cylindrical silicas have a hollow structure. Formation of diblock copolymers, polymer nanoobjects, polymer@silica hybrids, and silica nanoobjects was characterized by 1H NMR spectroscopy, size exclusion chromatography (SEC), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), solid state 29Si CPMAS NMR analysis, N2 adsorption–desorption measurements, and Fourier-transform infrared spectroscopy (FT-IR). This methodology could be a general approach to fabricate various inorganic nanoparticles with different geometric shapes.