Guorong Gao,Liufang Wang,Yang Cong,Zhenwu Wang,Yang Zhou,Rong Wang,Jing Chen,Jun Fu
Hydrogel actuators that deform in response to external stimuli have promising applications in diverse fields. It is desirable to develop robust hydrogels with multiple and synergistic stimuli responsiveness. This work reports on robust poly(NIPAM-co-DMAPMA)/clay hydrogel bilayers that undergo reversible and repeatable curling/uncurling in response to pH and/or temperature changes. The bilayers are fabricated by sequential synthesis of thermoresponsive N-isopropylacrylamide (NIPAM) and N-[3-(dimethylamino)propyl] methacrylamide (DMAPMA) monomers, which produces robust interface bonding between the layers. Different NIPAM/DMAPMA ratios were used between two gel layers to manipulate the asymmetric responsiveness, thus leading to curling/uncurling of bilayers upon exposure to stimuli. The hydrogel bilayers are fabricated into soft manipulators to grasp and release target objects by pH and temperature changes, and as artificial muscle to lift and move a hanging weight by synergistic pH and temperature stimuli. This work provides a new type of asymmetric responsive hydrogel bilayer with potential applications in biomimetic actuators.
Gas flotation is one of the important technologies for oily wastewater treatment and the surface-active polymer is an important kind of developing flotation agents. In this article, the flotation performance, polymerization kinetics, and copolymerization behavior of surface-active copolymer of N -[3-(dimethylamino) propyl] methacrylamide (DMAPMA) and dodecyl dimethyl propenyl ammonium chloride (C 12 DM) and copolymer of DMAPMA and decyl dimethyl vinylbenzyl ammonium chloride(C 10 MVBA) were investigated. The flotation experiment showed that both copolymers had an oil removal of 97% at the concentration of 30 mg/L. The result of polymerization kinetics showed that the polymerization initiation rate was influenced by the monomer concentration and the polymerization termination was dominated by bimolecular termination and accompanied by unimolecular termination. The activation energy of DMAPMA-C 12 DM copolymerization (89.64 kJ/mol) was smaller than that of DMAPMA-C 10 MVBA (91.65 kJ/mol) copolymerization. The reactivity ratios of DMAPMA and C 12 DM were 0.46 and 15.52, respectively, as well as the reactivity ratios of DMAPMA and C 10 MVBA were 1.19 and 35.77, respectively. These results are meaningful for the oily wastewater flotation and the copolymerization mechanism of DMAPMA-based copolymer.
Deepwater cementing technology holds non-negligible significance in ensuring the safe exploitation of deepwater oil and gas resources, and maintaining stability of hydrate formations is crucial for deepwater cementing. Traditional solutions primarily focus on reducing the cement’s hydration heat evolution but fail to effectively address the issue of hydrate dissociation. Therefore, our previous work outlined the design and optimization of a novel hydrate dissociation inhibitor, PVCap/dmapma, and its physical synthesis and evaluation are explored in this study. The method of molecular simulation and experimental study was utilized to establish an evaluation method of hydrate dissociation inhibitor under cementing environment, to investigate the hydrate decomposition inhibitory, and to determine the relatively optimal synthesis conditions and process. PVCap/dmapma exhibits excellent ability to delay the hydrate dissociation, and no adverse effects on cement thickening and mechanical properties compared to Lecithin. Our findings provide a certain theoretical foundation for the development of hydrate dissociation inhibitors for cementing and hold significant implications for ensuring the safe exploitation of deepwater oil and gas resources.
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