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The thermodynamic incompatibility between the soft and hard segments of thermoplastic polyurethane (TPU) results in a microphase-separated behavior and excellent mechanical properties. However, the effect of the chain extender on the degree of microphase separation (DMS) and the resultant mechanical properties of TPU have not been well studied because of the complex interactions between the soft and hard segments. Herein, hydroxyl-terminated polybutadiene-based TPUs(HTPB-TPUs) without hydrogen bonding between the soft and hard segments are synthesized using hydroxyl-terminated polybutadiene, toluene diisocyanate, and four different chain extenders, and the effect of the chain extender structure on DMS is analyzed experimentally using a combination of analytical techniques. Furthermore, the solubility parameters of the soft and hard segments, glass transition temperatures, and hydrogen-bond density of the HTPB-TPUs, are computed using all-atom molecular dynamics simulations. The results clearly reveal that the chain extender significantly affects the DMS and thus the mechanical properties of HTPB-TPUs. This study paves the way for studying the relationship between the structure and properties of TPU., (© 2024 Wiley‐VCH GmbH.)

A systematic theoretical study was conducted on the triel bonds (TrBs) within the TrX 3 ···Be(CO) 3 complexes (Tr = B, Al, Ga, In, Tl; X = H, F, Cl, Br, I). The interaction energies of these systems range between 4 and 38 kcal/mol. The TrB weakens as X becomes more electronegative in the B and Al systems, while the opposite pattern of stronger bonds is observed in the In and Tl analogues. The dominant component of the TrB is polarization energy, which arises from charge transfer from Be(CO) 3 to TrX 3 . The source of the density is a confluence of CO π-bonding orbitals at the Be center that resembles a Be lone pair, and which makes the molecular electrostatic potential above the Be somewhat negative. This π-lump is paired with the highly positive π-hole above the Tr, and a large amount of charge is transferred to the empty p z orbital of Tr. These factors, when considered in conjunction with large AIM measures, confer on this TrB a certain degree of covalency.

A systematic theoretical study was conducted on the triel bonds (TrB) within the BH 3 ∙∙∙M(MDA) 2 and C 5 H 4 BX∙∙∙M(MDA) 2 (M = Ni, Pd, Pt, X = H, CN, F, CH 3 , NH 2 , MDA = enolated malondialdehyde) complexes, with BH 3 and C 5 H 4 BX acting as the electron acceptors and the square-coordinated M(MDA) 2 acting as the electron donor. The interaction energies of these systems range between -4.71 and -33.18 kcal/mol. The larger the transition metal center M, the greater the enhancement of the TrB, with σ-hole TrBs found to be stronger than π-hole TrBs. In the σ-hole TrB complex, an electron-withdrawing substituent on the C opposite to the B atom enhances the TrB, while an electron-donating substituent has little effect on the strength of TrB in the Pd and Pt complexes but enhances the TrB in the Ni-containing complexes. The van der Waals interaction plays an important role in stabilizing these binary systems, and its contribution diminishes with increasing M size. The orbital effect within these systems is largely due to charge transfer from the d z 2 orbital of M into the empty p z orbital of B.

The tetrel bond between PhXF 2 Y(TF 3 ) (T = C and Si; X = Cl, Br, and I; Y = F and Cl) and the electron donor MCN (M = Li and Na) was investigated at the M06-2X/aug-cc-pVDZ level of theory. As the electronegativity of the halogen atom X increases, the strength of the tetrel bond also increases, but as the electronegativity of the halogen atom Y increases, the strength of the tetrel bond decreases. The magnitude of the interaction energy in most -CF 3 complexes was found to be less than 10 kcal/mol, but to exceed 11 kcal/mol for PhClF 2 Cl(CF 3 )⋯NCNa. The tetrel bond is greatly enhanced when the -SiF 3 group interacts with LiCN or NaCN, with the largest interaction energy approaching 100 kcal/mol and displaying a covalent Si⋯N interaction. Along with this enhancement, the Si⋯N distance was found to be less than the X-Si bond length, the -SiF 3 group to be closer to the N atom, and in most -SiF 3 systems, the X-Si-F angle to be less than 90°; the -SiF 3 group therefore undergoes inversion and complete transfer in some systems.

The tetrel bond (TB) between 1,2-benzisothiazol-3-one-2-TF 3 -1,1-dioxide (T = C, Si) and the O atom of pyridine-1-oxide (PO) and its derivatives (PO-X, X = H, NO 2 , CN, F, CH 3 , OH, OCH 3 , NH 2 , and Li) is examined by quantum chemical means. The Si∙∙∙O TB is quite strong, with interaction energies approaching a maximum of nearly 70 kcal/mol, while the C∙∙∙O TB is an order of magnitude weaker, with interaction energies between 2.0 and 2.6 kcal/mol. An electron-withdrawing substituent on the Lewis base weakens this TB, while an electron-donating group has the opposite effect. The SiF 3 group transfers roughly halfway between the N of the acid and the O of the base without the aid of cooperative effects from a third entity.

The novel triel bonds of BX 3 (X=H, F, Cl, Br, and I) and C 5 H 5 B as electron acceptors and AuR 2 (R=Cl and CH 3 ) as an electron donor were explored. The triel bond is a primary driving force for most complexes, while the contribution from a halogen-chlorine interaction in BX 3 -AuCl 2 (X=Cl, Br, and I) and an iodine-Au interaction in BI 3 -Au(CH 3 ) 3 is also very important. Interestingly, the positively charged Au atom of AuCl 2 can attractively bind with the holes of BX 3 and C 5 H 5 B. The interaction energy lies in the range of 1 and 80 kcal/mol, in the order X=F5 H 5 B is stronger than the triel bond of BX 3 . In the formation of B-Au triel bond, electrostatic energy is not dominant, while polarization energy including orbital interaction has the largest contribution for the strongly bonded complexes and dispersion energy for the weak triel bond., (© 2022 Wiley-VCH GmbH.)

Vibration and noise-reduction materials are indispensable in various fields. Polyurethane (PU)-based damping materials can dissipate the external mechanical and acoustic energy through molecular chain movements to mitigate the adverse effects of vibrations and noise. In this study, PU-based damping composites were obtained by compositing PU rubber prepared using 3-methyltetrahydrofuran/tetrahydrofuran copolyether glycol, 4,4'-diphenylmethane diisocyanate, and trimethylolpropane monoallyl ether as raw materials with hindered phenol, viz., and 3,9-bis{2-[3-(3- tert -butyl-4-hydroxy-5-methylphenyl)proponyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane (AO-80). Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and tensile tests were conducted to evaluate the properties of the resulting composites. The glass transition temperature of the composite increased from -40 to -23 °C, and the tan δ Max of the PU rubber increased by 81%, from 0.86 to 1.56 when 30 phr of AO-80 was added. This study provides a new platform for the design and preparation of damping materials for industrial applications and daily life.

Polylactic acid (PLA) has received increased attention in the development of shape-memory polymers and biomedical materials owing to its excellent physical properties and good biocompatibility and biodegradability. However, the inherent brittleness and high shape-recovery temperature of this material limit its application in the human body. Herein, we fabricated a PLA-based thermoplastic polyurethane (PLA-TPU) prepared from modified PLA-diol, dicyclohexylmethane-4,4'-diisocyanate, and 1,4-butanediol to solve the limitations of pure PLA. The glass transition temperature ( T g ) of the designed TPU can be tailored from 6 to 40.5 °C by adjusting the content of hard segments or molecular weight of soft segments. The shape of the designed TPU can be fixed at room temperature and recovered at temperatures above 37 °C. Moreover, the prepared PLA-TPUs exhibited recyclability, three-dimensional printing capability, non-cytotoxicity, blood compatibility, and biodegradability. The shape of PLA-TPU/nano-Fe 3 O 4 composites can be recovered by exposure to near-infrared light. These results collectively indicate that PLA-TPUs and their composites may have potential applications as intelligent flexible medical scaffolds for surgical and medical implantation equipment.

Objectives: This study aims to propose a novel and effective throat swab collection method for coronavirus disease 2019 (COVID-19)., Methods: The subjects were randomly divided into two groups. The subjects were asked to open their mouth to make "ah" sound (traditional method) or simulate yawn (improved method) for throat swab collection. The usage of tongue depressor, collection time, adverse reactions and subjective discomfort (VAS score) were compared. The collection time, comprehensive indicators of adverse reactions and VAS score were also compared among three collectors., Results: The tongue depressor was less used in the improved group (χ 2 = 40.186, P < 0.01). The average collection time of the traditional group was 5.44 ± 2.97 and that of the improved group was 4.00 ± 2.31 (P < 0.01). The subjects in the improved group had fewer and milder adverse reactions. The VAS score of subjects in the improved group was lower than that in the traditional group (P < 0.01). Among different collectors, the collection time, comprehensive indicators of adverse reactions and VAS were the same as the overall trend., Conclusion: Simulating yawn is a safer and faster throat swab collection method., (Copyright © 2021 Elsevier Inc. All rights reserved.)

One of the goals of bone tissue engineering is to mimic native ECM in architecture and function, creating scaffolds with excellent biocompatibility, osteoinductive ability and mechanical properties. The aim of this study was to fabricate nanofibrous matrices by electrospinning a blend of poly (L-lactic-co-glycolic acid) (PLGA), hydroxyapatite (HA), and grapheme oxide (GO) as a favourable platform for bone tissue engineering. The morphology, biocompatibility, mechanical properties, and biological activity of all nanofibrous matrices were compared. The data indicate that the hydrophilicity and protein adsorption rate of the fabricated matrices were significantly increased by blending with a small amount of HA and GO. Furthermore, GO significantly boosted the tensile strength of the nanofibrous matrices, and the PLGA/GO/HA nanofibrous matrices can serve as mechanically stable scaffolds for cell growth. For further test in vitro, MC3T3-E1 cells were cultured on the PLGA/HA/GO nanofbrous matrices to observe various cellular activities and cell mineralization. The results indicated that the PLGA/GO/HA nanofibrous matrices significantly enhanced adhesion, and proliferation in MCET3-E1 cells and functionally promoted alkaline phosphatase (ALP) activity, the osteogenesis-related gene expression and mineral deposition. Therefore, the PLGA/HA/GO composite nanofibres are excellent and versatile scaffolds for applications in bone tissue regeneration.

Background: With radiotherapy (RT) alone, the five-year overall survival (OS) rate for advanced nasopharyngeal carcinoma (NPC) can only reach 40%, the ratio of distant metastasis (DM) is 36-40%. This meta-analysis was performed to compare the clinical efficacy of concurrent chemoradiotherapy (CCRT) with RT alone in the treatment of locoregionally advanced NPC., Methods: The related literature were retrieved and reviewed by two independent investigators from the followed electronic databases: Review manager 5.3 software (Cochrane Collaboration, London, United Kingdom) was applied for statistical analysis., Results: A total of 16 trials with 2576 patients were recruited according to the criterion. The odds ratios of 3 and 5 years OS was 0.53 (95% confidence interval [95% CI]: 0.44-0.64) and 0.58 (95% CI: 0.48-0.71), which confirmed the significant improvement of CCRT compared with RT alone (P < 0.001). CCRT also reduced the risk of locoregional control failure and DM in locoregionally advanced NPC patients., Conclusions: The results suggested that CCRT was more beneficial when compared with RT alone in locoregionally advanced NPC patients. Further study is needed to perform to confirm this effect.