Effect on the thermal resistance and thermal decomposition properties of thermally cross-linkable polyimide films obtained from a reactive acetylene

Customized Copolymer composite coatings for carbon capture Environments: Corrosion inhibition and CO2 barrier Synergy

Global warming is attributed to excessive emissions of greenhouse gases, which are being addressed through the deployment of carbon capture technologies aimed at mitigating climate change. However, this approach faces significant challenges, as high concentrations of CO2 pose a huge risk of corrosion, compromising integrity. The active inhibitor polyfluoroaniline grown on the surface of graphene (Gr-PFAN) is encapsulated in epoxy novolac (EN) coating. And highly reactive nitrogen-containing poly(p-phenylenediamine-fluoroaniline) (Gr-PPFAN) was synthesized by changing the polymerization monomer. For the first time, primary amine nitrogen-containing active sites are discussed in CO2 shielding material. The gas transmission rate (GTR) test showed that the GTR of the composite film containing Gr-PPFAN was 3.7 times higher than that of Gr-PFAN. And the presence of highly reactive amines in the polymer mass transfer behavior was calculated by molecular simulation. Therefore, the PPFAN coating is a serious failure in H2O-CO2 environment. The introduction of the low content of active sites in Gr-PFAN into the epoxy resin matrix resulted in significant enhancement of the H2O, H2O-CO2 and H+ corrosion resistance. The small amount of active amine not only enhances the phase interface between the resin and the flake filler, but also facilitates the formation of a protective layer on the metal surface. Experimental results demonstrated that Gr-PFAN/EN exhibited the highest |Z|0.01 Hz value (3.5 × 1011 O × cm2) after 90 days of immersion in 3.5 wt% NaCl solution and 1.5 × 1011 O × cm2 for 30 days in the carbon capture environment. Furthermore, it makes Gr-PFAN/EN a promising candidate for practical applications in CO2 capture projects. The findings provide a scientific basis for the development of efficient anti-corrosion coatings suitable for carbon capture technologies.

Solvothermal Preparation of Microporous Polyureas for Au(III) Adsorption

The enrichment and recovery of gold from wastewater are an alternative method to obtain this noble metal, which benefits reducing hazardous emissions from the conventional ore mining process and reserving natural gold for sustainable development. Inspired by our previous work (Lei et al., Macromol. Rapid Comm. 2022, 2200712), four families of microporous polyureas (mPPUs) with a large surface area (690 m2 g-1) and abundant heteroatom sites have been prepared via the factor-optimized solvothermal protocol. The resultant sample NPU-A starting from 1,5-naphthalene diisocyanate (NDI) and tri(4-aminophenyl) amine (TAPA) exhibits the maximum Au(III) adsorption capacity of 1300 mg g-1 and high selectivity even when the Au(III) concentration is as low as 0.1 mg L-1. This study not only demonstrates the robustness of the high-throughput synthetic strategy but also promotes the investigation of the structure-activity correlation between the mPPU chemical structure and Au(III) adsorption performance.

Interpenetration Networked Polyimide-Epoxy Copolymer under Kinetic and Thermodynamic Control for Anticorrosion Coating

Epoxy (EP) was copolymerized with polyamic acid (PAA, precursor of polyimide (PI)) with termanil monomers of (1) 4,4'-Oxydianiline (ODA) and (2) pyromellitic dianhydride (PMDA) individually to form (PI-O-EP) and (PI-P-EP) copolymers. The FTIR spectrum of PI-O-EP copolymerization intermediates shows that some amide-EP linkages were formed at low temperature and were broken at higher temperature; in additoin, the released amide was available for subsequent imidization to form PI. The curing and imidization of the amide groups on PAA were determined by reaction temperature (kinetic vs. thermodynamic control). In PI-P-EP, the released amide group was very short-lived (fast imidization) and was not observed on FTIR spectra. Formation and breakage of the amide-EP linkages is the key step for EP homopolymerization and formation of the interpenetration network. PI contributed in improving thermal durability and mechanical strength without compromising EP's adhesion strength. Microphase separations were minimal at PI content less than 10 wt%. The copolymerization reaction in this study followed the "kinetic vs. thermodynamic control" principle. The copolymer has high potential for application in the field of higher-temperature anticorrosion.

Improved Melt Processabilities of Thermosetting Polyimide Matrix Resins for High Temperature Carbon Fiber Composite Applications

With the goal of improving processability of imide oligomers and achieving of high temperature carbon fiber composite, a series of Thermosetting Matrix Resin solutions (TMR) were prepared by polycondensation of aromatic diamine (3,4'-oxybisbenzenamine, 3,4-ODA) and diester of biphenylene diacid (BPDE) using monoester of 4-phenylethynylphthalic acid (PEPE) as end-capping agent in ethyl alcohol as solvent to afford phenylethynyl-endcapped poly(amic ester) resins with calculated molecular weight (Calc'd Mw) of 1500-10,000. Meanwhile, a series of reactive diluent solutions (RDm) with Calc'd Mw of 600-2100 were also prepared derived from aromatic diamine (4,4'-oxybisbenzenamine, 4,4-ODA), diester of asymmetrical biphenylene diacid (α-BPDE) and monoester of 4-phenylethynylphthalic acid (PEPE) in ethyl alcohol. Then, the TMR solution was mixed with the RDm solution at different weight ratios to afford a series of A-staged thermosetting blend resin (TMR/RDm) solutions for carbon fiber composites. Experimental results demonstrated that the thermosetting blend resins exhibited improved melt processability and excellent thermal stability. After being thermally treated at 200 °C/1 h, the B-staged TMR/RDm showed very low melt viscosities and wider processing window. The minimum melt viscosities of ≤50 Pa·s was measured at ≤368 °C and the temperature scale at melt viscosities of ≤100 Pa·s were detected at 310-390 °C, respectively. The thermally cured neat resins at 380 °C/2 h showed a great combination of mechanical and thermal properties, including tensile strength of 84.0 MPa, elongation at breakage of 4.1%, and glass transition temperature (Tg) of 423 °C, successively. The carbon fiber reinforced polyimide composite processed by autoclave technique exhibited excellent mechanical properties both at room temperature and 370 °C. This study paved the way for the development of high-temperature resistant carbon fiber resin composites for use in complicated aeronautical structures.