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Polymeric elastomers play an increasingly important role in the development of stretchable electronics. A highly demanded elastic matrix is preferred to own not only excellent mechanical properties, but also additional features like high toughness and fast self‐healing. Here, a polyurethane (DA‐PU) is synthesized with donor and acceptor groups alternately distributed along the main chain to achieve both intra‐chain and inter‐chain donor‐acceptor self‐assembly, which endow the polyurethane with toughness, self‐healing, and, more interestingly, thermal repair, like human muscle. In detail, DA‐PU exhibits an amazing mechanical performance with elongation at break of 1900% and toughness of 175.9 MJ m−3. Moreover, it shows remarkable anti‐fatigue and anti‐stress relaxation properties as manifested by cyclic tensile and stress relaxation tests, respectively. Even in case of large strain deformation or long‐time stretch, it can almost completely restore to original length by thermal repair at 60 °C in 60 s. The self‐healing speed of DA‐PU is gradually enhanced with the increasing temperature, and can be 1.0–6.15 µm min−1 from 60 to 80 °C. At last, a stretchable and self‐healable capacitive sensor is constructed and evaluated to prove that DA‐PU matrix can ensure the stability of electronics even after critical deformation and cut off.

Arthroscopic reduction and fixation of a bony Bankart lesion can achieve good results in selected cases. The size of the reconstructed glenoid is crucial to the success of the surgery.

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Ionic skin (I-Skin) has the advantage of feasible compatibility with biological systems. Nevertheless, developing a stable and durable ionic skin is challenging. Here, an ionic polyurethane (i-PU) is synthesized, which is capable of self-healing and able to lock the ionic liquids (ILs). In detail, an ionic chain extender containing an ammonium cationic group is synthesized, followed by the polymerization to obtain the target i-PU. Through electrostatic interaction and chain diffusion, the i-PU can be fully self-healed at room temperature within 400 min. Afterward, low contact angle (37°) of the i-PU against IL and the density functional theory (DFT) calculation prove their good compatibility and strong interaction, originating from the electrostatic interaction. The Raman intensity map shows the reversible process of the enrichment and restoration of ionic concentration on the i-PU/IL surface when external pressure is applied or released, proving stable binding of ions by ionic polymer chains. Lastly, the self-healing I-Skin based on the i-PU/IL is fabricated with a wide range of pressures (0-120 kPa), fast response time (32 ms), excellent antifatigue property (2% attenuation after 1000 cycles), and remarkable sensitivity (52.4 kPa -1 ).

The very slow degradation of biodegradable polymers in the marine environment is due to the lack of dedicated degradation enzymes in open seas. As a result, introducing monomers that have a fast hydrolysis process is required to accelerate seawater degradation. Poly(butylene succinate-co-glycolate) (PBSGA) copolyesters with glycolic acid (GA) units ranging from 5 to 40% were synthesized by our newly developed polymerizing method based on oligo(glycolic acid). The results of 1 H-NMR and GPC revealed that short GA segments were evenly distributed between BS segments, obtaining random copolyesters with a weight-average molecular weight over 6.24 * 10 4 g/mol. The copolymerized GA units hinder its crystallization capability and increase hydrophilicity of the PBSGAs, which still displayed mechanical properties comparable or even better than most biodegradable polymers. Fast degradation in seawater and enzymatic environments (Candida antarctica lipase B enzymes) is proved experimentally. The quick decomposition in seawater was originated from accelerated hydrolysis. For instance, the weight loss of PBSGA40 (compositions of GA units) exceeded 22% after 49 days. Possible degradation mechanisms were proposed based on Fukui function analysis and frontier molecular orbital calculation. Additionally, the energy barrier for hydrolysis was calculated by the density functional theory method, indicating that the hydrolysis of the polymer chain became more and more easy with the increase in GA units. At last, the addition of GA units only had a mild effect on the shelf life of the PBSGAs.

Background:The effect of selective and non-selective cyclooxygenase (COX) inhibitors on tendon healing was variable. The purpose of the study was to evaluate the influence of non-selective COX inhibitor, ibuprofen and flurbiprofen axetil and selective COX-2 inhibitor, celecoxib on the tendon healing process in a rabbit model.Methods:Ninety-six New Zealand rabbits were used as rotator cuff repair models. After surgery, they were divided randomly into four groups: Ibuprofen (10 mg·kg−1·d−1), celecoxib (8 mg·kg−1·d−1), flurbiprofen axetil (2 mg·kg−1·d−1), and control group (blank group). All drugs were provided for 7 days. Rabbits in each group were sacrificed at 3, 6, and 12 weeks after tendon repair. Tendon biomechanical load failure tests were performed. The percentage of type I collagen on the bone tendon insertion was calculated by Picric acid Sirius red staining and image analysis. All data were compared among the four groups at the same time point. All data in each group were also compared across the different time points. Qualitative histological evaluation of the bone tendon insertion was also performed among groups.Results:The load to failure increased significantly with time in each group. There were significantly lower failure loads in the celecoxib group than in the control group at 3 weeks (0.533 vs. 0.700, P = 0.002), 6 weeks (0.607 vs. 0.763, P = 0.01), and 12 weeks (0.660 vs. 0.803, P = 0.002), and significantly lower percentage of type I collagen at 3 weeks (11.5% vs. 27.6%, P = 0.001), 6 weeks (40.5% vs. 66.3%, P = 0.005), and 12 weeks (59.5% vs. 86.3%, P = 0.001). Flurbiprofen axetil showed significant differences at 3 weeks (failure load: 0.600 vs. 0.700, P = 0.024; percentage of type I collagen: 15.6% vs. 27.6%, P = 0.001), but no significant differences at 6 and 12 weeks comparing with control group, whereas the ibuprofen groups did not show any significant difference at each time point.Conclusions:Nonsteroidal anti-inflammatory drugs can delay tendon healing in the early stage after rotator cuff repair. Compared with nonselective COX inhibitors, selective COX-2 inhibitors significantly impact tendon healing.

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