•Biodegradable hydrogels with both good mechanical properties and high water content were obtained.•A simple and scalable strategy for the preparation of a biodegradable PU prepolymer was described.•The prepolymer forms a poly(urethane-urea) hydrogel in few minutes when mixed with water.•The maximum water retaining capacity of the hydrogel can be up to 38 times of PU prepolymer (in mass).The synthesis of biodegradable hydrogels with both good mechanical properties and high water content is still a great challenge. In this study, a simple and scalable strategy for the preparation of a biodegradable polyurethane prepolymer composed of isocyanate terminated linear polyethylene glycol (L-PEG) and isocyanate terminated three-armed poly(l-lactic acid) (T-PLLA) is described. When mixed with water, the prepolymer forms a poly(urethane-urea) hydrogel in few minutes. The effect of the molecular weight and the feeding ratio of L-PEG and T-PLLA on the mechanical property of the poly(urethane-urea) hydrogel is discussed. The resulting hydrogel shows good mechanical properties with high tensile strength (up to 108 KPa) and recorded elongation rate (4500%), while maintaining high water content (up to 91% mass ratio). Meanwhile, the maximum water retaining capacity of the hydrogel can be up to 38 times of PU prepolymer (in mass), which is equal to 97.4% water content. Its degradation property is analyzed by the loss of tensile strength and cross section morphology through SEM with time. Such a low cost and biodegradable poly(urethane-urea) hydrogel, which combines fast hydrogel formation, high water content and good mechanical properties, might be used as potential candidates for applications in agrological field, such as sand fixing in desertification control.

A mussel-inspired adhesive based on a polyvinylpyrrolidone (PVP) backbone shows a much higher bonding strength under underwater/seawater conditions than under dry conditions. We reasoned that besides catechol moieties, the structure and properties of the backbone also play an important role in the realization of strong underwater bonding.

Mussel-inspired catechol-containing polymers have drawn great attention due to their outstanding adhesive properties. Catechol-containing polyethylene glycol (cPEG) is a well-studied catechol-containing polymer used for tissue repair. Nevertheless, catechols can only be attached to the chain ends of polyethylene glycols thus the bonding strength of the resulting polymers is limited. Aiming at solving the problem, a series of clickable polyoxetane copolymers with grafted catechol moieties were synthesized in an efficient manner. Upon addition of FeCl3 as the cross-linker, strong bonding strength of the adhesive was achieved. Polymer containing 15.5 molar percent of catechol showed the strongest bonding strength up to 5.59 MPa on sanded stainless steel. It was found that the triazole groups also contributed to the overall adhesive performance. This polyoxetane-based adhesive also displayed strong bonding ability to a variety of other substrates including porcine skin.

A mussel-inspired adhesive based on a polyvinylpyrrolidone (PVP) backbone shows a much higher bonding strength under underwater/seawater conditions than under dry conditions. We reasoned that besides catechol moieties, the structure and properties of the backbone also play an important role in the realization of strong underwater bonding.