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Difunctional glycidyl azide polymer (GAP) is an energetic binder promising for propellant formulations. The multifunctional fluorine‐containing GAP has been synthesized to enhance its mechanical properties. This work outlined multifunctional GAP partially grafted with 1,2,3‐triazole‐5‐(α‐hydroxyl)‐fluorinated polyether (GAP‐g‐3F) synthesized by thermal and catalyst‐free azide‐alkyne cycloaddition reaction, in which the azide groups were from GAP and electron‐deficient alkynes from β‐propargyl‐α‐hydroxyl poly (tri‐fluoropropane glycidyl ether) (PHP3F). PHP3F was synthesized via the typical cationic ring‐opening polymerization of 2‐((2,2,2‐trifluoroethoxy) methyl) oxirane and propargyl alcohol as the initiator. The chemical structures, molecular weight, and thermal properties were characterized by FTIR, NMR, GPC, DSC, and TGA, respectively. HNMR results showed that 8 % of total azide groups in GAP were grafted. GAP‐g‐3F had a slightly higher glass transition temperature than that of GAP. The results of TGA showed that GAP‐g‐3F had suitable thermal decomposition resistance up to 200 °C. The thermal properties, mechanical properties, cross‐linking network structures, and microstructures of the polyurethane networks cured with hexamethylene diisocyanate trimer as a crosslinking agent were determined and compared by TGA, universal tensile test, swelling measurement, and SEM, respectively. The initial decomposition temperature of GAP‐g‐3F‐based polyurethane networks (GAP‐g‐3F‐PU) was around 220 °C, thus meeting the requirements for propellants. In addition, GAP‐g‐3F‐PU exhibited superior mechanical properties, showing an almost twelvefold increase in tensile strength to 16.9 MPa compared with difunctional GAP‐PU with 1.4 MPa tensile strength. The results of the swelling measurement revealed that the GAP‐g‐3F‐PU sample showed a higher crosslinking density in comparison to the GAP‐PU sample. SEM results indicated that the multifunctional fluorine‐containing GAP could enhance compatibility between the soft and hard segments of polyurethanes, leading to a decrease in their separation degree. This finding showed that the synthesis of a multifunctional GAP partially grafted with fluorinated polyether via a triazole ring may be a promising solution to decrease the separation degree increase of PUs, thereby improving the mechanical properties. [ABSTRACT FROM AUTHOR]

This work reports the kinetics of anionic ring‐opening polymerization of hexaethylcyclotrisiloxane (D3Et) with potassium trimethylsilanolate as initiator and diglyme and N,N‐dimethylformamide (DMF) as promoters. The polymerization rate of D3Et is influenced by the nature of promoters and the reaction temperatures. With the use of DMF as a promoter, the polymerization activation energy is 107.89 kJ/mol, and the polymerization rate constant at 110°C is 0.08466 min−1 with [P]/[I] = 3.0. Gel permeation chromatography and 29Si NMR spectra showed that the intermolecular redistribution occurred during the late stage of polymerization, which facilitated the synthesis of high‐molecular‐weight polydiethylsiloxane (PDES). Differential scanning calorimetry analysis showed that PDES exhibited a glass transition temperature of −142°C and complex crystallization phenomena. Thermogravimetric analysis illustrated that the PDES that was prepared using this method had good thermal stability with onset decomposition temperatures of 483 and 452°C under nitrogen and air conditions, respectively. This work presents innovative approaches for achieving a more energy‐efficient synthesis of PDES to meet the demands of industrial‐scale production. [ABSTRACT FROM AUTHOR]

• Synthesis of biobased polyamide 4 by anionic polymerization of 2-pyrrolidone. • Preparation of nanofibers by electrospinning and their characterization. • Test of degradation of nanofibers in water environment for a long period. • Nanofiber layers are hydrolytically stable. Based on renewable raw materials, polyamide 4 has excellent mechanical properties, high hydrophilicity, and cotton-like water sorption. The problem is its low thermal stability near its melting point, which does not allow melt processing. With the development of the technology of electrostatic spinning of polymers from solutions, the attention of researchers has returned to polyamide 4. In this work, nanofiber layers of polyamide 4 with molar masses of 18,000 and 280,000 g/mol and diameters of 350 ± 60 and 270 ± 10 nm, respectively, were prepared by electrostatic spinning from a mixed solution of formic acid and dichloromethane. Subsequently, the layers were subjected to degradation in phosphate buffer at 37 and 60 °C. The electrostatic spinning process was shown to result in a decrease in the molar mass of the samples. During degradation in buffer at pH 7.4, the molar mass does not change significantly, but there is a change in the structure of the nanofibrous layers by bonding of the fibers, especially for low molecular weight PA4. In contrast to other studies, polyamide 4 is hydrolytically stable even in the form of nanofiber layers. [ABSTRACT FROM AUTHOR]

Low dielectric photoinduced patterned materials have attracted extensive attention owing to their potential applications in integrated circuits and semiconductor devices. In this work, we synthesized a low dielectric polymer that can be used for photolithography. The monomer, 1-(4-vinylphenyl)-2-(4-benzocyclobutenyl)ethene (DVB-S-BCB), was synthesized from divinylbenzene (DVB) and 4-bromobenzocyclobutene (4-BrBCB) using the Heck reaction. Subsequently, P-DVB based on DVB-S-BCB was prepared by anionic polymerization. As the structure comprised thermally curable benzocyclobutene (BCB) groups and photocurable vinyl groups (UV/Thermal dual curing structure), P-DVB has been used for high-performance negative photosensitive resin with 2,6-bis(4-azidobenzylidene) cyclohexanone (BAC) as a photoinitiator. Photolithography was carried out using a 365-nm UV light source to obtain various patterns, and the research results indicate that photosensitive resins exhibit stable patterning processes at different curing stages. Besides, the cured P-DVB exhibited high thermal stability (T 5% above 420 °C in N 2), low dielectric constant (2.55 at 10 MHz), low dielectric loss (1.56 × 10−3 at 10 MHz), and excellent mechanical performance. These properties make P-DVB a potential photoresist that can be widely used as interconnected dielectrics. P-DVB containing vinyl groups and benzocyclobutene groups was synthesized by anionic polymerization. This resin exhibits low D k and high-resolution photo-imageable dielectric performance. Therefore, it is expected to be used for integrated circuits and semiconductor devices. [Display omitted] • Rapid synthesis of photosensitive resins with photo-thermal curing structures on a large scale, and at low cost. • Have high-resolution photo-imageable and process flexibility (spin coating or dry film, patterning, developing). • UV/Thermal double cured structure gives excellent mechanical properties, low dielectric properties and low CTE. • Widely used in high-density, low-power packages such as WLP, RDL, TSV, etc., promoting integration and miniaturization. [ABSTRACT FROM AUTHOR]