Polymer Science, Series B最新文献

Silicone-modified polyurethane has low silicon content and instability of the synthesis process limits its application expansion. In this study, the waterborne organosilicon acrylic polyurethane prepolymer emulsion with high silicon content (WSi_hAPU) were prepared by using hydroxy-terminated polydimethyl siloxane as soft segments. Waterborne organosilicon acrylic polyurethane (WSiAPU) can be controlled by simple mixing the ratio of WSi_hAPU and waterborne acrylic polyurethane (WAPU) in different proportions, and the WSiAPU films were freely regulate their silicon content range at 0–11.6%. Series WSiAPU emulsions had excellent storage stability, which can be diluted mechanically to a concentration of 0.1% and stored for up to 6 months. The structure and properties of the WSiAPU samples, their films by UV cured and the fabric subtract coating WSiAPU composites were characterized by the X-ray Photoelectron spectroscopy (XPS), the water contact angle (WCA) and water absorption rate (WAR), etc. This resulted in an increase in the hydrophobicity of WSi_hAPU and WSiAPU. The WCA and the WAR of the WSiAPU films increased to 108.79° and decreased to 6.44%, and the WAR of the WSiAPU treated fabric substrates Cotton was reduced from 705.12 to 4.12%. This resulted in an increase in the hydrophobicity of WSi_hAPU and WSiAPU.

Liquid hydridopolycarbosilanes (LHPCS) is commonly used to produce ceramic matrix composites by polymer impregnation pyrolysis (PIP) process. Allyl-substituted hydridopolycarbosilanes (AHPCS) with different allyl contents of 10, 15, 20, 25 and 30 mol % (AHPCS-10%, AHPCS-15%, AHPCS-20%, AHPCS-25%, AHPCS-30%) were synthesized by Grignard coupling reaction. tert-Butyl peroxybenzoate (TBPB) + cobalt 2-ethylhexanoate (Co) were used as the redox initiation system for AHPCS curing and was compared with Karstedt catalyst and TBPB initiator. Based on differential scanning calorimetry analyses, the TBPB + Co initiation system significantly decreased the exothermic peak temperature of the free radical polymerization to 80°C. According to thermogravimetric analysis, the residual at 1000°C of cured AHPCS-20% in flowing nitrogen reached to 86.0%. Ceramized AHPCS were obtained by heat treated cured AHPCS at 1500°C for 2 h. Based on the X-ray diffraction patterns and transmission electron microscope photographs of the ceramic products, β-SiC was the main component of the ceramized AHPCS. Ceramized AHPCS-15% was the highest ceramic yield of 88.1% in the ceramized AHPCS. Thermogravimetric analyses revealed high thermal oxidation resistance of the ceramic AHPCS in flowing air up to 1000°C. Therefore, AHPCS under TBPB + Co initiation system with low-temperature curability and high ceramic yield, and its ceramic products have excellent thermal oxidation resistance, showing potential as SiC ceramic precursors for aerospace field.

Electrically conductive composite textile and textile combining electrically conductive and magnetic properties have been obtained on the basis of biocompatible non-toxic materials: commercial non-woven textiles, electrically conductive polypyrrole and magnetite (Fe₃O₄). The composite textile has been formed from two-layer fibers, where the fibers of the original textile are coated with a polypyrrole shell, and the textile combining electrically conductive and magnetic properties have had a three-layer structure, where magnetite particles are deposited on top of the polypyrrole shell. The composite textiles have retained the structure of the original fabric with free interfiber space: the specific surface area of the materials and their mechanical properties have been similar in value. The composition of materials, their electrically conductive, magnetic, and redox properties have been investigated. The interaction of the composite textile and the textile combining electrically conductive and magnetic properties with electromagnetic radiation in the frequency range of 4–8 GHz have been investigated in comparison with a commercial radio-absorbing material based on carbonyl iron.

β-ocimene (3,7-dimethyl-1,3,6-octatriene), a dimer of isoprene, which can be found in various essential oils such as ocimium plant genus, holds the potential to serve as a source material for creating elastomers entirely derived from bio-based sources. Due to its structural similarity to myrcene (C₁₀H₁₆), this conjugated diene, offers the possibility of undergoing polymerization using the same method employed for myrcene. This involves the utilization of neodymium trisborohydride as a pre-catalyst activated by boron derivatives in the presence of triisobutyl aluminum. This innovative approach has led to the successful production of 1,4-cis polyocimene, a significant achievement in the field of polymer chemistry. Detailed analysis through the application of ¹³C NMR and DEPT 135 spectroscopy has shed light on the microstructure of the resulting polyocimene. It has been revealed that the polymer exhibits a predominant microstructure of 1,4‑cis (comprising up to 83.38% of the structure) along with the presence of 1,2-trans isomer (constituting 16.62%). The findings also highlight that the molecular weight distributions of the polymer are relatively broader (PDI > 2). This catalytic system enables the production of polymers that can be used as promising starting materials for bio-based thermoplastic elastomers.

Mesoporous silica nanoparticles (MSNs) were synthesized by alkaline catalysis, hydrolysis condensation reactions, and template removal of tetraethoxysilane (TEOS). MSNs were used as fillers and carriers to immobilize polymer components and form three-dimensional grids within the material, thus imparting the absorbent resin with the required mechanical strength. Carboxymethyl chitosan (CTS) was used as the substrate for synthesizing composite water absorbent resin. A composite superabsorbent resin was prepared by grafting copolymerization with acrylamide (AM) and acrylic acid (AA) and it was referred to as MSNs@CTS-g-P(AA-co-AM). The liquid absorption and adsorption performances of heavy metal ions were examined in different environments. The results showed that the water absorption rate of MSNs@CTS-g-P(AA-co-AM) reached 740 g/g at water absorption equilibrium. Compared with known organic/inorganic composite water absorbing resins, the composite resin involving MSNs had good water retention performance, which was evident from the water retention rate reaching a maximum of 91.8% when the resin was dried at 80°C for 6 h. This was attributed to the composite resin forming a stable three-dimensional network structure due to the MSNs, strong salt resistance, and better adsorption performance.

In this paper, amino terminated polydimethylsiloxane (APT-PDMS) was synthesized by ring opening reaction of octamethylcyclotetrasiloxane (D4). Then, the slippery liquid infused porous surfaces (SLIPS) of polyimide were prepared from APT-PDMS, 1,2,4,5-cyclohexane tetracarboxylic dianhydride (HPMDA) and 2,2'-bis[4-(4-aminophenoxyphenyl)] propane (BAPP) by two-step method. The composition and structures of products were characterized by Fourier transform infrared spectroscopy (FTIR), the thermal stability of the substrate was studied by thermogravimetric analyzer, the surface morphology and properties of the substrate was observed by scanning electron microscope and Contact angle test. The results show that Slide angle (SA) and stability were the best when the polymer concentration was 30 mg/mL, and the slip angle after oil filling was 3°. Compared with the superhydrophobic surface, the SLIPS own excellent anti-icing and anti-freezing performance, thermal stability, and antibacterial adhesion performance.

With the use of quantum-chemical and kinetic methods, the influence of free amino groups in amine monomers on the rate of their reaction with ethylene carbonate is studied. It was stated that the catalytic effect in diamine appears at the length of the chain of 3–7 atoms. A decrease in activation barriers is associated with the formation of less strained proton transfer and stabilization cycles in transition states. The theoretically found dependence of the rates of aminolysis of ethylenecarbonate on the structure of amines is confirmed experimentally by kinetic measurements.

1,3-Dioxolane polymer (PDXL) was synthesized using Halloysite, a natural clay material, as solid acid catalyst for cationic ring-opening polymerization. This catalyst was activated with 0.5 M sulfuric acid solution to increase its Brønsted-type acidity. Polymerization of DXL was carried out in bulk under magnetic stirring at low temperature, leading to the formation of polydioxolane. The Halloysite and synthesized polymer were characterized by several techniques including X-ray fluorescence (XRF), X-ray diffraction (XRD), Infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). To assess the dispersing power of the synthesized PDXL and its hydration activity, the setting time, consistence and compressive strength of cement paste and mortar containing poly(1,3-dioxolane) was studied, compared to the commercial polyethylene glycol (PEG) used as reference in this study. The results showed the retarding effect of PDXL on the setting times of cement paste, accompanied by a decrease in normal consistency, which allows its use as superplasticizer or dispersant agent. Thus, PDXL improved the compressive strength of cement mortar compared to PEG polymer effect.

This study focused on thermosetting high-ortho phenolic epoxy fibers prepared by blending thermosetting high-ortho phenolic resins (HOT-PRs) with F-704 epoxy resins and using dry spinning, thermal curing, and microwave curing methods. The structure was characterized by infrared spectroscopy, microinfrared spectroscopy, nuclear magnetic resonance spectroscopy, and scanning electron microscopy. The heat resistance of different fibers was studied by thermogravimetric analysis, and the mechanical properties of the fibers were determined using a fiber tensile strength tester. Results showed that the HOT-PRs successfully used the phenolic hydroxyl groups and the hydroxyl groups in the methylol groups to promote the ring-opening reaction of the epoxy groups to form ether bonds. The breaking strength of the thermally cured fibers was 206 MPa, and the elongation at break was 14.5%. The microwave-cured fibers had good heat resistance with an initial weight loss temperature of 315°C and a char yield of 59.7% at 800°C.

Glycidyl azide polymer (GAP) with tetra hydroxyl functional groups often known as tetra functional GAP or t-GAP is a potential energetic polymeric binder for high-energy composite solid rocket propellant and plastic bonded high explosive formulations. t-GAP is synthesized via azidation of the tetrafunctional precursor of poly-epichlorohydrine (t-PECH) by sodium azide in DMSO. In this article, synthesis of t-GAP is studied using IR-spectroscopy, and an attempt is made to monitor the reaction progress through characteristic IR absorption bands corresponding to C–N₃ in t-GAP and C–Cl in t-PECH vibrations aiming to optimize reaction parameters.