RESUMO
In this study, we investigated the effect of morphology on the gas-transport properties of a poly(ether-block-amide) (PEBA) multiblock copolymer. We annealed the copolymer samples and varied the annealing temperature to evaluate the influence of changes in the microstructure on the gas transport properties of PEBA. In addition, we used time-resolved attenuated total reflection Fourier transform infrared spectroscopy to evaluate the diffusion coefficient of CO2 in PEBA based on the Fickian model. The effect of the annealing temperature on the microphase-separated structure of the multiblock copolymer is discussed in detail. Furthermore, the gas diffusivity was significantly affected by the purity of the soft domains. The annealed sample demonstrated a 38% increase in CO2 permeability while maintaining a high CO2/N2 permselectivity of approximately 53. The findings of this study provide valuable insight into the design and optimization of PEBA membranes for gas separation applications.
RESUMO
The interfacial region between nanoparticles and polymer matrix plays a critical role in influencing the mechanical behavior of polymer nanocomposites. In this work, a set of model systems based on poly(methyl methacrylate) (PMMA) matrix containing poly(alkyl glycidyl ether) brushes grafted on 50 nm metal-organic-framework (MOF) nanoparticles were synthesized and investigated. By systematically increasing the polymer brush length and graft density on the MOF nanoparticles, the fracture behavior of PMMA/MOF nanocomposite changes from forming only a few large crazes to generating massive crazing and to undergoing shear banding, which results in significant improvement in fracture toughness. The implication of the present finding for the interfacial design of the nanoparticles for the development of high-performance, multifunctional polymer nanocomposites is discussed.
RESUMO
A novel semicrystalline poly(ether ketone) (PEK)-based proton exchange membrane (semi-SPEK-x) has been developed. Through a one-step sulfonation and hydrolysis, a poly(ether ketimine) precursor transforms into PEK and ion-conducting groups are introduced. With an ion-exchange capacity ranging from 1.49 to 2.00 mequiv g-1, the semi-SPEK-x polymers exhibit a semicrystalline feature in both dry and hydrated states. Owing to the semicrystalline domains inside the polymer, the obtained membrane exhibits low water uptake and low volume swelling ratio. More importantly, the semicrystalline structure lowers methanol permeability and, consequently, improves the overall performances of direct methanol fuel cells.
RESUMO
We have developed basic ionic liquid-based hybrid membranes with ionic liquid modified zeolitic imidazolate frameworks (ZIFs) as fillers, aiming to enhance the electrochemical and physical properties of the membrane.
