Synthesis of Betaine Copolymer for Surface Modification of Cotton Fabric by Enhancing Temperature-Sensitive and Anti-Protein Specific Absorption Performance

The growth and reproduction of microorganisms on fabrics could not only affect the wearability of textiles but also cause harm to human health, and it is an important problem that should be solved to reduce the adsorption and growth of microorganisms on the surface of the fabric. A series of ω-vinyl betaine copolymers were synthesized by catalytic chain transfer polymerization (CCTP) and were modified by mercapto-vinyl click chemistry to synthesize silane-modified betaine copolymers, which were used to treat the cotton fabric. The hydrophilic–hydrophobic transition performance and anti-protein specific adhesion performance of cotton fabric with the betaine copolymer were systematically investigated. The copolymer was confirmed to be successfully finished on the cotton fabric via ¹H–NMR and FTIR. The cotton fabric, which was treated by the betaine copolymer, presented temperature response performance in the range of 30–55 °C and had excellent anti-protein adsorption performance. The treated fabric had the best temperature-sensitive and anti-protein specific absorption performance among all the specimens when the mass fraction of G06B in DMAPS was 6 wt.%.     

Enzymatic Catalysis in Favor of Blocky Structure and Higher Crystallinity of Poly(Butylene Succinate)-Co-(Dilinoleic Succinate) (PBS-DLS) Copolymers of Variable Segmental Composition

To systematically investigate the synthesis of poly(butylene succinate)-co-(dilinoleic succinate) (PBS-DLS) copolymers and to enrich the library of polyesters synthesized via a sustainable route, we conducted a two-step polycondensation using fully biobased monomers such as diethyl succinate (DS), 1,4-butanediol (1,4-BD) and dilinoleic diol (DLD) in diphenyl ether, using Candida Antarctica lipase B (CAL-B) as biocatalyst. A series of PBS-DLS copolyesters with a 90-10, 70-30 and 50-50 wt% of hard (PBS) to soft (DLS) segments ratio were compared to their counterparts, which were synthesized using heterogenous titanium dioxide/silicon dioxide (TiO₂/SiO₂) catalyst. Chemical structure and molecular characteristics of resulting copolymers were assessed using nuclear magnetic spectroscopy (¹H- and ¹³C-NMR) and gel permeation chromatography (GPC), whereas thermal and thermomechanical properties as well as crystallization behavior were investigated by differential scanning microscopy (DSC), dynamic mechanical thermal analysis (DMTA), digital holographic microscopy (DHM) and X-ray diffraction (XRD). The obtained results showed that, depending on the type of catalyst, we can control parameters related to blockiness and crystallinity of copolymers. Materials synthesized using CAL-B catalysts possess more blocky segmental distribution and higher crystallinity in contrast to materials synthesized using heterogenous catalysts, as revealed by DSC, XRD and DHM measurements.     

Synthesis and Characterization of Flexible Meta-Aramid Modified with 4,4′-Methylenedianiline

Meta-aramids (poly(m-phenylene isophthalamide), PMIA) have excellent flame, heat resistance, and electrical insulation. However, the rigid molecular backbone of PMIA and the strong hydrogen bonding force between its molecular chains make it poorly flexible, soluble, and processed. In this study, a series of modified PMIA containing methylene groups on the main chain (APMIA-n, where n is the molar fraction of 4,4′-methylenedianiline (MDA) in m-phenylenediamine, and n = 0, 5, 10, 15, 20) is synthesized by introducing different ratios of MDA into PMIA by copolymerization. APMIA-n films are prepared by the solution casting method. The results show some improvement in the solubility of APMIA-n in polar organic solvents such as N,N-dimethylformamide and dimethyl sulfoxide. With the increase of the molar fraction of MDA, the tensile modulus of obtained APMIA-n films decrease from 4.62 to 2.98 GPa, indicating that the flexibility of the films is evidently increased. APMIA-n films are self-extinguishing which suggests that the addition of MDA during copolymerization has a slight influence on the flame resistance of the synthesized PMIA. Moreover, APMIA-n films containing MDA components exhibit good optical transparency, which may expand the application of PMIA in more fields such as packaging and screen display.     

Crystallizability of Free and Tethered Chains in Nanometer-Sized Droplets

Confining polymers to nanometric sizes often interferes with the characteristic length scales of structure formation and thus significantly alters crystallization or nucleation behavior at the nanoscale. To investigate such effects in nanometric samples, past studies relied either on heavily constraining environments like block copolymer mesophases or on deposited droplets that exhibit significant variation in size, thus requiring extensive analysis to assign size classes. This studypresents a novel method to create nanometer-sized polymer droplets of narrow volume distribution and to study their dynamic and thermodynamic behavior using the change in orientational polarization. A combination of gold-nanoparticle deposition with a grafting-to reaction and a nanostructured electrode setup enabled the measurement of poly-ε-caprolactone (PCL) droplets consisting of ten chains on average for a relatively small molecular weight. Distinct crystallization and melting signatures in spin-cast droplets demonstrate the sensitivity of this approach. In contrast, the grafted aggregates exhibit no signs of crystallization, which is attributed to considerable constraints in this configuration, like limited chain motion or too wide chain spacing. Nevertheless, the presented setup is capable of studying ensembles of individualized (macro-) molecules.     

One-Step Polymerizations Enable Facile Construction and Structural Optimization of Graft Copolymer Electrolytes

The development of poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) is limited by the semi-crystalline nature of PEO and the extremely strong EO-Li⁺ interactions. To promote the rapid migration of Li⁺, a one-step method combining radical polymerization and ring-opening polymerization catalyzed simultaneously by lithium carboxylate is proposed to construct multi-component graft copolymer electrolytes (GCPEs) in this study. Tailored macroinitiator with catalytic and initiated sites (PAALi(OH-Br)) realizes one-step polymerizations of vinyl monomers and cyclic monomers, and provides GCPEs with poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) side chains. The grafted structure of GCPE greatly facilitates the intra-chain hopping of Li⁺, resulting in excellent ionic conductivity. The introduction of PCL further improves the t_Li+ of GCPE. The three-component graft copolymer electrolyte constructed by polystyrene (PS), PEO, and PCL exhibits high tensile stress (1.62 MPa), a high ionic conductivity (2.4 × 10⁻⁵ S cm⁻¹, 30 °C), and a high t_Li+ of 0.47 and high electrochemical stability.     

Middle Meningeal Artery Embolization with Liquid Embolic Agents for Chronic Subdural Hematoma: A Systematic Review and Meta-analysis

PurposeTo assess the efficacy and safety of middle meningeal artery (MMA) embolization with liquid embolic agents and the outcomes of patients following this procedure.Materials and MethodsA review of the literature was conducted to identify studies investigating the efficacy and safety of MMA embolization with liquid embolic agents in patients with chronic subdural hematoma (cSDH) in PubMed, Scopus, Embase, and Web of Science. The keywords “liquid embolic agent,” “middle meningeal artery,” “cSDH,” and “embolization” as well as their synonyms were used to build up the search strategy. The R statistical software and random-effects model were used for analysis. Heterogeneity was reported as I², and publication bias was calculated using the Egger test.ResultsOf 628 articles retrieved, 14 studies were eligible to be included in this study. Data of 276 patients were analyzed. n-Butyl cyanoacrylate and ethylene vinyl alcohol copolymer were the most commonly used embolic agents. This study revealed a pooled mortality rate of 0% (95% confidence interval [CI], 0.00%–100%), recurrence and failure rate of 3% (95% CI, 1%–10%), reoperation/reintervention rate of 4% (95% CI, 2%–12%), rate of size decrease of 94% (95% CI, 79%–98%), technical success rate of 100% (95% CI, 76%–100%), and adverse event rate of 1% (95% CI, 0.00%–4%).ConclusionsWith low mortality, recurrence, reoperation, and adverse event rates and a remarkable decrease in the size of hematomas, MMA embolization with liquid embolic agents may be considered a safe and effective treatment option in patients in whom surgical intervention has previously failed and as an alternative to conventional treatments.     

Unveiling the Role of Compositional Drifts on the Tack of Pressure-Sensitive-Adhesives

Pressure-sensitive-adhesives (PSAs) are pervasive in electronic, automobile, packaging, and biomedical applications due to their ability to stick to numerous surfaces without undergoing chemical reactions. These materials are typically synthesized by the free radical copolymerization of alkyl acrylates and acrylic acid, leading to an ensemble of polymer chains with varying composition and molecular weight. Here, reversible addition−fragmentation chain-transfer (RAFT) copolymerizations in a semi-batch reactor are used to tailor the molecular architecture and bulk mechanical properties of acrylic copolymers. In the absence of cross-links, the localization of acrylic acid toward the chain ends leads to microphase separation, creep resistance, and enhanced tack. However, in the presence of Al(acac)₃ crosslinker, the creep resistance remains unchanged and mostly the large-strain mechanical properties are affected. This behavior is attributed to microphase separation, but also to a change in the energy required to break physical associations, and untangle and elongate associative polymers to large deformations.     

聚乳酸-羟基乙酸共聚物复合支架在骨缺损修复再生中的作用与应用北大核心

背景:聚乳酸-羟基乙酸共聚物由于具有良好的生物相容性、可塑性、完全降解性等优点成为人工骨源的理想材料,但其缺乏亲水性、不具有成骨诱导能力、降解产物酸化微环境等缺点不利于骨缺损修复,因此对其进行修饰改性就显得十分必要。目的:阐述聚乳酸-羟基乙酸共聚物复合支架的相关研究进展。方法:应用计算机检索中国知网、PubMed数据库2000年1月至2020年11月收录的文献,检索中文关键词为“聚乳酸-羟基乙酸共聚物、PLGA、骨缺损、复合支架、羟基磷灰石、磷酸三钙、改性、表面改性、共混修饰”,英文关键词为“Polylactic acid-hydroxyacetic acid copolymer,PLGA,bone defect,composite scaffold,hydroxyapatite,tricalcium phosphate,modification,surface modification,blending modification”,排除相关程度低、过于陈旧或重复的文献。结果与结论:聚乳酸-羟基乙酸共聚物支架的修饰方法众多,主要以共混修饰和表面修饰为主。共混修饰是通过在支架制造时掺入其他物质,如羟基磷灰石、磷酸三钙、氢氧化镁等无机物,可以提高支架的力学性能、亲水性,改变细胞行为,促进造骨。表面修饰是在支架表面包被一层活性物质,调节细胞-支架材料之间的相互作用。虽然通过各种改进方法支架的性能得到明显改善,但应用于临床仍面临许多困难。