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A facile method was found to incorporate a mussel-inspired adhesive moiety into synthetic polymers, and mussel mimetic polyurethanes were developed as adhesive hydrogels. In these polymers, a urethane backbone was substituted for the polyamide chain of mussel adhesive proteins, and dopamine was appended to mimic the adhesive moiety of adhesive proteins. A series of mussel mimetic polyurethanes were created through a step-growth polymerization based on hexamethylene diisocyanate as a hard segment, PEG having different molecular weights as a soft segment, and lysine-dopamine as a chain extender. Upon a treatment with Fe(3+), the aqueous mussel mimetic polyurethane solutions can be triggered by pH adjustment to form adhesive hydrogels instantaneously; these materials can be used as injectable adhesive hydrogels. Upon a treatment with NaIO4, the mussel mimetic polyurethane solutions can be cured in a controllable period of time. The successful combination of the unique mussel-inspired adhesive moiety with a tunable polyurethane structure can result in a new kind of mussel-inspired adhesive polymers.

ABSTRACT Inspired by mussel adhesive proteins, catechol functional groups play an important role in the ability of the mussel to adhere to organic and inorganic surfaces. A novel functional polyurethane (PU) based on hydrolysable tannins that contain a number of catechol groups was successfully synthesized and characterized. These catechol groups were used as a reducer for Ag (I) to form Ag (0), and to prepare polyurethane/silver nanoparticles composites. These kinds of polyurethane containing Ag nanoparticles showed obvious inhibition of bacterial growth because of the conjunct actions of the well-known antibacterial property of silver and the antifouling property of PEG. It is possible for these materials to be applied widely into antibacterial adhesive coatings for surface modification due to their low cost and the material-independent adhesive property of catechol groups in tannins. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41349. [ABSTRACT FROM AUTHOR]

Primary mono-amine (furfuryl amine) is functionalized as a chain extender to obtain linear polyurethane bearing pendant furan groups (L-PU-Furan), unlike the previous research (furanic diols as chain extender). Furfuryl amine can functionalize as a chain extender due to the reactivity between the resultant urea group and NCO group at higher temperatures. Pendant cross-linked polyurethane containing a DA bond (C-PU-DA) is obtained from the cross-linking of L-PU-Furan and a bismaleimide (BMI) via a Diels–Alder reaction. L-PU-Furan and C-PU-DA are characterized by 1H NMR, FTIR, DSC and TGA. The results of 1H NMR and gel–solution–gel experiments demonstrate that the C-PU-DA exhibits excellent thermal reversibility. C-PU-DA exhibits good healable properties as evidenced by the evolution of a crack versus temperature observed under polarizing optical microscopy. C-PU-DA exhibits good mechanical properties and healing efficiency, determined by breaking (tensile) strength measurements. [ABSTRACT FROM AUTHOR]

A novel adhering polyurethane (PU), based on hydrolysable tannins that contain a number of active sites, was successfully synthesized and characterized. The active sites were catechol groups in the hydrolysable tannins, which were used as a substitute for dopamine. This efficient, universal, and low cost coating based on hydrolysable tannins was cured by adding FeCl3, and was evaluated by nuclear magnetic resonance (1H-NMR), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and UV-Visible spectrophotometry (UV/Vis). The polyurethane coating containing tannins showed improved coating adhesion and an accelerated curing rate on the substrate, both of which were similar those of dopamine based PU coatings. The TGA and UV/Vis results indicated that the characteristics of the tannin-containing polyurethane were deeply related to the concentration of the tannins. [ABSTRACT FROM AUTHOR]

Abstract: Biodegradable polyurethanes were prepared from 11,11′-dithiodiundecanol employed as soft segment incorporating hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) serving as hard segment. The disulfide bonds in dithiodiundecanol could be cleaved into thiols in the presence of glutathione (GSH) through disulfide-thiol exchange reaction, which fulfilled the polyurethanes with responsive biodegradability. In vitro degradation test in PBS buffer at 37 °C, the molecular weight of polyurethanes substantially decreased and the surface morphology was significantly eroded after 8 days. The degradation reaction constants were calculated and kinetic equations were established. [Copyright &y& Elsevier]

Abstract: Two kinds of novel reduction-sensitive rapid degradable poly(urethane-urea)s were synthesized and characterized based on a cystine derivative chain extender which provided active sites for reductive degradation. In vitro degradation study was carried out under physiological conditions mediated by glutathione and dithiothreitol respectively, and was assessed by 1H NMR, GPC and SEM. The results indicated that the disulfide bonds in poly(urethane-urea)s were effectively cleaved while the structures of urethane groups and soft segments remained almost unaffected. Still, the rate and degree of reductive degradation could be controlled by the structures of the polymers. The influence of the poly(urethane-urea)s on human umbilical vein endothelial cells was investigated by WST-1 assay. The results indicated that the polymers sustained much higher cell viability than the controls. It is possible that the poly(urethane-urea)s can be potentially applied for temporary biomaterials such as wound closure devices, cell scaffolds and sophisticated drug delivery systems. [Copyright &y& Elsevier]