Macromolecular Chemistry and Physics最新文献

Lignin, an underutilized aromatic biopolymer from agricultural waste, is promising for functional hydrogels. However, the complex composition, molecular heterogeneity, and low active site accessibility of lignin severely restrict its practical applications. Traditional lignin extraction methods result in over 80% cleavage of β-O-4 bonds and a significant loss of phenolic hydroxyl groups. In this study, four different molecular weight lignins (F1-F4) were obtained from cotton stalks via γ-valerolactone pretreatment. The molecular weights of F1-F4 were 5203, 2926, 1956, and 938g/mol, with total phenolic hydroxyl contents of 0.03, 0.09, 0.27, and 0.54 mmol/g, respectively. Compared with hydrogels of the high-molecular-weight lignin (F1), the low-molecular-weight lignin-based hydrogel (F4) exhibited 3.32-fold enhanced elasticity, 4.23-fold improved conductivity, and 1.52-fold higher antibacterial activity. Notably, the γ-valerolactone pretreatment preserved β-O-4 bonds more effectively, while increasing the pore size by 1.57-fold. These results indicated that the low-molecular-weight lignin with high phenolic hydroxyl content conferred the hydrogel with significantly enhanced elasticity, conductivity, and antibacterial activity, making it highly promising for applications in drug delivery, wound healing, and wearable biosensors. This work demonstrates a green route to valorize agricultural lignin into high-performance hydrogel materials.

The synthesis of crystalline hyper-crosslinked polymer still challenges scientists due to the irreversible, random nature of the Friedel–Crafts reaction. In this work, we report a series of crystalline TPA-CC-x combined by 1, 3, 5, 7-tetraphenyladamantane (TPA) and cyanuric Chloride (CC) based on Friedel–Crafts reaction. The X-ray diffraction (XRD) analysis confirmed the crystal structure of these polymers. The porosity and pore size distribution analysis discovered that the spec, while the TPA-CC-x were almost entirely composed of micropores with the pore diameter approximately located at 1.223 nm. Combining the advantages of abundant adsorption sites, electronegative natures, and porous structures, TPA-CC–1 exhibits ultrahigh adsorption capacities and adsorption rates toward cationic dyes, including malachite green (MG) and Rhodamine B (RhB). Notably, the maximum adsorption capacity of TPA-CC–1 toward RhB is 2089.3 ± 55.3 mg g⁻¹, which exceeded all previously reported porous manuscript organic polymers adsorbents. The contribution represents the first report of crystalline HCPs that not only expand their structural diversity but also exhibit excellent adsorption properties.

In this study, a series of cross-linked poly(glycerol sebacate itaconic) (PGSIA) was prepared using a two-step method, involving pre-PGS oligomers with varying hydroxyl contents and molecular weights. The effects of different pre-PGS oligomers on the structure and properties of the cross-linked PGSIAs were investigated. Upon increasing the pre-PGS molecular weight, the degree of cross-linking degree of the PGSIA increased accordingly. Young's modulus and tensile strength increased dramatically from 1.97 and 1.25 MPa to 24.94 and 7.82 MPa, respectively. Meanwhile, the glass transition temperature (T_g) increased from −15.5°C to −5.3°C. The water contact angle increased from 62.3° to 88.0°, and the degradation mass loss decreased from 12.8% to 4.3%. Upon increasing the hydroxyl content, the degree of cross-linking degree increased, along with the increase in the Young's modulus, which increased from 3.17 to 9.97 MPa, while tensile strength increased from 1.35 to 3.39 MPa. The T_g decreased gradually from −7.5°C to −19.8°C. The water contact angle increased from 47.9° to 80.4°, and the loss of degradation mass loss increased from 6.1% to 23.5%. In this work, poly(glycerol sebacate itaconic) (PGSIA), was prepared by a solvent-free melt process as a green chemistry advantage.

Although many flame retardants have been synthesized for bisphenol A diglycidyl ether (DGEBA), those with high flame retardancy remain scarce. In this study, the flame retardant of 6,6',6''-((pyrimidine-2,4,6-triyltris(azanediyl))tris(thiophen-2-ylmethylene))tris(dibenzo[c,e][1,2]oxaphosphinine 6-oxide) (TTD) containing N, P and S has been successfully synthesized from 2,4,6-triaminopyrimidine, 2-thiophenecarboxaldehyde and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and characterizations of FTIR and ¹H and ³¹P NMR confirm its chemical structure. The flame-retardant epoxy resin (EP/DDM/TTD) is prepared by blending DGEBA, TTD, and 4,4’-diaminodiphenylmethane (DDM). Among all EP/DDM/TTD formulations, EP/DDM/TTD12.5 achieves a V-0 rating and 39.4% LOI, indicating TTD has high flame retardancy. Meanwhile, EP/DDM/TTD12.5 shows 24.0% and 23.2% lower THR and TSP than EP/DDM, respectively. EP/DDM/TTD7.5 has 40.98% and 38.82% higher tensile and flexural strength than EP/DDM, respectively. TTD's flame retardant mechanism is studied via various characterizations. Various characterizations of char residue of EP/DDM and EP/DDM/TTD12.5 indicate that TTD has a flame-retardant effect on DGEBA in the condensed phase. Meanwhile, PY-GC-MS analysis of TTD's pyrolysis behavior reveals that TTD also exerts a flame-retardant effect on DGEBA in the gaseous phase. This work opens up possibilities for the application of DGEBA in fields requiring high flame-retardant performance.

Ferrocene-based burn rate catalysts (BRCs) have attracted much attention for use in solid propellant (SP) because of their excellent microscopic homogeneities in distribution, good compatibility with organic binder and enhancing the ignitability of the SP. Though the Butacene (butyl-ferrocene grafted hydroxyl-terminated polybutadiene), the most popular BRC, is commercially available, the reported synthetic routes of Butacene are tedious, inconsistent, misleading and often not reproducible. This article presents an alternative, readily executable, industrially scalable and reproducible synthetic method for the preparation of Butacene and the resulting samples were characterized by various techniques, including spectroscopic, molecular weight, viscosity and thermal, etc. This work also first time demonstrates that the percentage of iron content in Butacene, which is a crucial factor to be effective as BRC, can be readily altered by varying monomer to initiator ratio. All the physical characteristic measurements showed that the resulting Butacene has the required physical properties to be used as BRC in the propellant formulation. Further, the solid composite propellant prepared using the synthesized Butacene displayed significantly higher burn rate and lower pressure index in comparison to pristine HTPB. A 50% enhancement in the burn rate with low pressure index (0.27) was observed in the case of SP, which was made using only 30% of synthesized Butacene along with 70% pristine HTPB. Further, the synthesized Butacene were cured to prepare polyurethanes (PUs) which showed similar thermal profile, glass transition temperature (T_g) and excellent mechanical properties like pristine HTPB.