Optimal molecular design of poly (ionic liquids) for CO2 capture from the atmosphere

Polymeric ionic liquids (PILs) are promising CO2 adsorption materials for that they combine the unique properties of ionic liquids with the flexibility and properties of macromolecular architectures. Previous studies have demonstrated that a carbonated-functionalized quaternary ammonium based PIL could adsorb CO2 from atmosphere when dry and release CO2 when wet, which constituted a moisture swing cycle, which provides an economical approach for air capture. Moreover, the performance of the PIL (such as CO2 affinity, reaction kinetics, swing size and hydrophobicity), could be improved owing to its fine tunability. To find out its optimal structure, molecular simulation was conducted to investigate the effects of phenyl, distance between cations, substituents and anions, on the properties of this PIL. In this work, quantum chemistry calculations were performed at the B3LYP/6-311++G** level of theory to obtain the geometrical parameters after interaction between cation-anion, ion-CO2, and ion-H2O. The reaction kinetics of CO2 adsorption for PILs with different structures are analyzed based on the calculated results. At last, the influence of backbone on hydrophobicity was discussed. The molecular structure investigated in this work is relatively large, and ONIOM method was adopted to save the computational cost, which is shown in Fig. 1. The results indicate that phenyl plays an important role in CO2 adsorption reaction. The large π bond of phenyl could attract lots of positive charges from quaternary ammonium, which would decrease the interactions between anions and cations. Besides, the phenyl could increase the mobility of the cations by elongating their arms, which would lead to the decrease of activation energy of proton transfer process. The distance between cations shows a great influence on CO2 adsorption reaction (see Fig. 2), and can be tuned by change its degree of crosslinking and monomer of its backbone. A distance of 8.5 Å could be the best choice for the relatively low activation energy and relatively high free energy change. The substituent on the phenyl could affect the charge distribution as well as the interactions between anions and cations. More importantly, we can tune the hydrophobicity for application in different environments by choosing different substituents. Those groups, which could form H-bonds with hydrated water, could enhance the hydrophilia greatly. The anions that could form strong H-bonds with hydrated water and whose products after adsorption show different H-bond distribution, have the potential of moisture swing. The swing size was determined by the degree of difference of water affinity between reactant and product. Carbonate anion has been proved the best choice for its large swing size and strong affinity of CO2. In a word, the optimal structure of this PIL should be carbonated-functionalized, have phenyl in its arms and keep the distance between cations around 8.5 Å

Preparation and characterization of PA6/titania conductive fibres

The surface activity of TiO2 has been modified by using sodium hexametaphosphate to improve its dispersibility in matrix. The modified TiO2 nanoparticles have been mixed with polyamide 6(PA6) into granulation, and then white conductive fibres are prepared using different weight ratios by melt spinning. The as-spun fibres are characterized by using high insulation resistance meter, scanning electron microscopy, X-ray diffraction and differential scanning calorimeter. The results show that the treated conductive TiO2 material is well dispersed in the PA6 matrix with good compatibility and that the electrical conductivity of as-spun fibres is excellent. Considering the mechanism of its electrical conductivity,it is concluded that the conductive mechanism is tunnel when the TiO2 content is less than 5%, the mechanism is composition of both tunnel and ohmic when TiO2 content is between 10% and 15%, and it is ohmic conductive mechanism if the TiO2 content is more than 15%

Are Fair Weather Fans Affected by Weather? Rainfall, Habit Formation and Live Game Attendance

We analyze habit formation in sports attendance utilizing rainfall as an unexpected, transitory shock to attendance costs. Using attendance data from Major League Baseball (MLB) and NOAA weather data, we analyze the impact of variation in game day weather conditions on current and future MLB attendance. The empirical strategy permits identification of both the formation and persistence of habit from exogenous weather shocks. Past adverse weather shocks increase future attendance by about 200 fans per game. Our study contributes to the literature developing empirical evidence of habit formation in the field and provides policy implications for optimal ticket pricing strategies

Detangling the Interrelationships Between Self-Regulation and Ill-Structured Problem Solving in Problem-Based Learning

One of the goals for problem-based learning (PBL) is to promote self-regulation. Although self-regulation has been studied extensively, its interrelationships with ill-structured problem solving have been unclear. In order to clarify the interrelationships, this article proposes a conceptual framework illustrating the iterative processes among problem-solving stages (i.e., problem representation and solution generation) and self-regulation phases (i.e., planning, execution, and reflection). The dynamics of the interrelationships are further illustrated with three ill-structured problem-solving examples in different domains (i.e., information problem solving, historical inquiry, and science inquiry). The proposed framework contributes to research and practice by providing a new lens to examine self-regulation in ill-structured problem solving and offering guidelines to design effective tools and strategies to scaffold and assess PBL