Recent Advances in Environmentally Friendly Dual-crosslinking Polymer Networks.

Environmentally friendly crosslinked polymer networks feature degradable covalent or non-covalent bonds, with many of them manifesting dynamic characteristics. These attributes enable convenient degradation, facile reprocessibility, and self-healing capabilities. However, the inherent instability of these crosslinking bonds often compromises the mechanical properties of polymer networks, limiting their practical applications. In this context, environmentally friendly dual-crosslinking polymer networks (denoted EF-DCPNs) have emerged as promising alternatives to address this challenge. These materials effectively balance the need for high mechanical properties with the ability to degrade, recycle, and/or self-heal. Despite their promising potential, investigations into EF-DCPNs remain in their nascent stages, and several gaps and limitations persist. This Review provides a comprehensive overview of the synthesis, properties, and applications of recent progress in EF-DCPNs. Firstly, synthetic routes to a rich variety of EF-DCPNs possessing two distinct types of dynamic bonds (i.e., imine, disulfide, ester, hydrogen bond, coordination bond, and other bonds) are introduced. Subsequently, complex structure- and dynamic nature-dependent mechanical, thermal, and electrical properties of EF-DCPNs are discussed, followed by their exemplary applications in electronics and biotechnology. Finally, future research directions in this rapidly evolving field are outlined.

The Profile of Early Sedation Depth and Clinical Outcomes of Mechanically Ventilated Patients in Korea.

BACKGROUND: Current international guidelines recommend against deep sedation as it is associated with worse outcomes in the intensive care unit (ICU). However, in Korea the prevalence of deep sedation and its impact on patients in the ICU are not well known. METHODS: From April 2020 to July 2021, a multicenter, prospective, longitudinal, noninterventional cohort study was performed in 20 Korean ICUs. Sedation depth extent was divided into light and deep using a mean Richmond Agitation-Sedation Scale value within the first 48 hours. Propensity score matching was used to balance covariables; the outcomes were compared between the two groups. RESULTS: Overall, 631 patients (418 [66.2%] and 213 [33.8%] in the deep and light sedation groups, respectively) were included. Mortality rates were 14.1% and 8.4% in the deep and light sedation groups (P = 0.039), respectively. Kaplan-Meier estimates showed that time to extubation (P < 0.001), ICU length of stay (P = 0.005), and death (P = 0.041) differed between the groups. After adjusting for confounders, early deep sedation was only associated with delayed time to extubation (hazard ratio [HR], 0.66; 95% confidence interval [CI], 0.55-0.80; P < 0.001). In the matched cohort, deep sedation remained significantly associated with delayed time to extubation (HR, 0.68; 95% CI, 0.56-0.83; P < 0.001) but was not associated with ICU length of stay (HR, 0.94; 95% CI, 0.79-1.13; P = 0.500) and in-hospital mortality (HR, 1.19; 95% CI, 0.65-2.17; P = 0.582). CONCLUSION: In many Korean ICUs, early deep sedation was highly prevalent in mechanically ventilated patients and was associated with delayed extubation, but not prolonged ICU stay or in-hospital death.

Exploring Anomalous Charge Storage in Anode Materials for Next-Generation Li Rechargeable Batteries.

To advance current Li rechargeable batteries further, tremendous emphasis has been made on the development of anode materials with higher capacities than the widely commercialized graphite. Some of these anode materials exhibit capacities above the theoretical value predicted based on conventional mechanisms of Li storage, namely insertion, alloying, and conversion. In addition, in contrast to conventional observations of loss upon cycling, the capacity has been found to increase during repeated cycling in a significant number of cases. As the internal environment in the battery is very complicated and continuously changing, these abnormal charge storage behaviors are caused by diverse reactions. In this review, we will introduce our current understanding of reported reactions accounting for the extra capacity. It includes formation/decomposition of electrolyte-derived surface layer, the possibility of additional charge storage at sharp interfaces between electronic and ionic sinks, redox reactions of Li-containing species, unconventional activity of structural defects, and metallic-cluster like Li storage. We will also discuss how the changes in the anode can induce capacity increase upon cycling. With this knowledge, new insights into possible strategies to effectively and sustainably utilize these abnormal charge storage mechanisms to produce vertical leaps in performance of anode materials will be laid out.

Polymorphic Effects on Electrochemical Performance of Conversion-Based MnO2 Anode Materials for Next-Generation Li Batteries.

In this study, four different MnO2 polymorphs are synthesized with a controlled morphology of hollow porous structures to systematically investigate the influences of polymorphs in conversion-based material. As the structure of these materials transforms into nanosized metal and maintains an extremely low-crystalline phase during cell operation, the effects of polymorphs are overlooked as compared to the case of insertion-based materials. Thus, differences in the ion storage behaviors among various MnO2 polymorphs are not well identified. Herein, the structural changes, charge storage reaction, and electrochemical performance of the different MnO2 polymorphs are investigated in detail. The experimental results demonstrate that the charge storage reactions, as part of which spinel-phased MnO2 formation is observed after lithiation and delithiation instead of recovery of the original phases, are similar for all the samples. However, the electrochemical performance varies depending on the initial crystal structure. Among the four polymorphs, the spinel-type λ-MnO2 delivers the highest reversible capacity of ≈1270 mAh g-1 . The structural similarity between the cycled and pristine states of λ-MnO2 induces faster kinetics, resulting in the better electrochemical performance. These findings suggest that polymorphs are another important factor to consider when designing high-performance materials for next-generation rechargeable batteries.

Additional Lithium Storage on Dynamic Electrode Surface by Charge Redistribution in Inactive Ru Metal.

Beyond a traditional view that metal nanoparticles formed upon electrochemical reaction are inactive against lithium, recently their electrochemical participations are manifested and elucidated as catalytic and interfacial effects. Here, ruthenium metal composed of ≈5 nm nanoparticles is prepared and the pure ruthenium as a lithium-ion battery anode for complete understanding on anomalous lithium storage reaction mechanism is designed. In particular, the pure metal electrode is intended for eliminating the electrochemical reaction-derived Li2 O phase accompanied by catalytic Li2 O decomposition and the interfacial lithium storage at Ru/Li2 O phase boundary, and thereby focusing on the ruthenium itself in exploring its electrochemical reactivity. Intriguingly, unusual lithium storage not involving redox reactions with electron transfer but leading to lattice expansion is identified in the ruthenium electrode. Size-dependent charge redistribution at surface enables additional lithium adsorption to occur on the inactive but more environmentally sensitive nanoparticles, providing innovative insight into dynamic electrode environments in rechargeable lithium chemistry.

The dark side of mobile work during non-work hours: moderated mediation model of presenteeism through conservation of resources lens.

Owing to the development of Information and Communication Technology (ICT) and the inevitability of telecommuting in the COVID-19 environment, the boundary between working and non-working hours has become blurred. mWork, that is, ICT-based off-hour work, which has increased through the pandemic, affects employees' work attitudes, such as presenteeism. Hence, we designed a study to investigate the antecedents and mechanisms of employee presenteeism from the perspective of the conservation of resources theory. We supported our hypothesis using a sample of 325 Korean office workers obtained through three rounds of time-delay surveys. The results show that presenteeism is higher among employees with high mWork. In addition, employees' mWork increases sleep deprivation and presenteeism, and the exchange ideology of employees reinforces the positive effect of sleep deprivation on presenteeism. Additionally, the higher the level of exchange ideology, the stronger the mediating effect of mWork on presenteeism through sleep deprivation. This study verified the conservation of resources theory by identifying the mechanism by which mWork affects an employee's life, which in turn affects their work, and provides practical implications for managing productivity loss due to presenteeism.

The Impact of COVID-19 Infection on Trauma Patients in South Korea.

BACKGROUND: The COVID-19 pandemic has significantly affected societies worldwide, including the medical healthcare system and trauma care. This study explores the impact of COVID-19 infection on trauma patients in South Korea, a country with effective pandemic management. METHODS: A retrospective cohort study of 4206 trauma patients from June 2020 to May 2022 was conducted. Patients were categorized into COVID-19-positive and COVID-19-negative groups. Various clinical parameters, complications, and mortality rates were analyzed. RESULTS: COVID-19-positive patients exhibited higher rates of complications, such as pressure sores (8.8% vs. 2.3%, p < 0.001), surgical site infections (2.4% vs. 0.8%, p = 0.044), and pneumonia (8.8% vs. 4.1%, p = 0.007). There was no significant difference in mortality between COVID-19-positive and -negative groups (4% vs. 5.6%, p = 0.439). Factors influencing mortality included COVID-19 status, age, Glasgow Coma Scale, Injury Severity Score, and transfusion status. CONCLUSION: COVID-19 positivity may have adverse clinical effects on trauma patients, but the impact varies based on public health factors. Additional studies in different contexts are crucial to elucidate these complexities.

Characteristics and Effectiveness of Mobile- and Web-Based Tele-Emergency Consultation System between Rural and Urban Hospitals in South Korea: A National-Wide Observation Study.

(1) Background: The government of South Korea has established a nationwide web- and mobile-based emergency teleconsultation network by designating urban and rural hospitals. The purpose of this study is to analyze the characteristics and effectiveness of the tele-emergency system in South Korea. (2) Methods: Tele-emergency consultation cases from May 2015 to December 2018 were analyzed in the present study. The definition of a tele-emergency in the present study is an emergency consultation between doctors in rural and urban hospitals via a web- and mobile-based remote emergency consultation system (RECS). Consultations through an RECS are grouped into three categories: medical procedure or treatment guidance, image interpretation, and transportation requests. The present study analyzed the characteristics of the tele-emergency system and the reduction in unnecessary transportation (RUT). (3) Results: A total of 2604 cases were analyzed in the present study from 2985 tele-emergency consultation cases. A total of 381 cases were excluded for missing data. Consultations for image interpretation were the most common in trauma cases (71.3%), while transfer requests were the most common in non-trauma cases (50.3%). Trauma patients were more frequently admitted to rural hospitals or discharged and followed up with at rural hospitals (20.3% vs. 40.5%) after consultations. In terms of disease severity, non-severe cases were statistically higher in trauma cases (80.6% vs. 59.4%; p < 0.001). The RUT was statistically highly associated with trauma cases (60.8% vs. 42.8%; p < 0.001). In an analysis that categorized cases by region, a statistically higher proportion of transportation was used in island regions (69.9% vs. 49.5%; p < 0.003). More RUT was associated with non-island regions (30.1% vs. 50.5%; p = 0.001). (4) Conclusions: The tele-emergency system had a great role in reducing unnecessary patient transportation in non-severe trauma cases and non-island rural area emergency cases. Further research is needed for a cost/benefit analysis and clinical outcomes.

Creativity in the South Korean Workplace: Procedural Justice, Abusive Supervision, and Competence.

Innovation is now a feature of daily life. In a rapidly changing market environment and amid fierce competition, organizations pursue survival and growth through innovation, and the key driver of innovation is the creativity of employees. Because the value of creativity has been emphasized, many organizations are looking for effective ways to encourage employees to be creative at work. From a resource perspective, creativity at work can be viewed as a high-intensity job demand, and organizations should encourage it by providing and managing employee resources. This study is an attempt to empirically investigate how competence and abusive supervision affect the relationship between procedural justice and creativity from the conservation of resources perspective. Findings from two-wave time-lagged survey data from 377 South Korean employees indicate that procedural justice increases creativity through the mediation of competence. Furthermore, abusive supervision has a negative moderating effect on the relationship between procedural justice and competence. The findings show that competence moderates the relationship between procedural justice and creativity and that the lower the level of abusive supervision, the greater the effect of procedural justice on competence and creativity.

Unveiling the Genesis and Effectiveness of Negative Fading in Nanostructured Iron Oxide Anode Materials for Lithium-Ion Batteries.

Iron oxide anode materials for rechargeable lithium-ion batteries have garnered extensive attention because of their inexpensiveness, safety, and high theoretical capacity. Nanostructured iron oxide anodes often undergo negative fading, that is, unconventional capacity increase, which results in a capacity increasing upon cycling. However, the detailed mechanism of negative fading still remains unclear, and there is no consensus on the provenance. Herein, we comprehensively investigate the negative fading of iron oxide anodes with a highly ordered mesoporous structure by utilizing advanced synchrotron-based analysis. Electrochemical and structural analyses identified that the negative fading originates from an optimization of the electrolyte-derived surface layer, and the thus formed layer significantly contributes to the structural stability of the nanostructured electrode materials, as well as their cycle stability. This work provides an insight into understanding the origin of negative fading and its influence on nanostructured anode materials.

Understanding the effect of nonmetallic impurities in regenerated cathode materials for lithium-ion battery recycling by tracking down impurity elements.

The regeneration of cathode materials would be the highest value-added direction in lithium-ion battery (LIB) recycling research. Li[NixMnyCoz]O2 (NMC) is regenerated from actual industrial scale LIB leachate and purified leachate to investigate the precipitation behavior of impurities, which include potentially toxic elements, such as F, Cl, and S. Regenerated precursors from the actual leachate, purified precursors, and a control sample are synthesized using the hydroxide co-precipitation method. Additionally, simulated precursors from simulated leachate are prepared in order to separate the effects of nonmetallic elements from the effects of metallic elements. The structure and electrochemical properties of the regenerated precursors and the corresponding cathode materials are examined. We first detect the presence of a significant amount of nonmetal elements, such as F as well as well-known metal elements, which include Al, Cu, and Fe, in the regenerated NMC. The concept of yield of precipitation (YOP) is introduced to assess the precipitation behavior of each element during the co-precipitation of the precursors. According to the concentration and YOP in the leachate and the precursors, six metal and three nonmetal elements are categorized. This categorization of impurity elements will certainly provide the LIB recycling industry with a valuable quality control guide.

Toward more useful pressure-controlled discography: in vitro evaluation of injection speed, sensor location, and tube length.

OBJECTIVE: Pressure-controlled manometric discography is used by clinicians to evaluate discogenic pain. However, some would improve diagnostic accuracy. The goal of this study was to investigate potential confounding factors that might affect discographic results. Pressure differences depending on different speed of injection, lengths of connecting tubing and locations of sensors were evaluated using an in vitro model system. METHODS: Two sets of automated discography devices were arranged to record post-syringeal pressure pressures (PSPs) and intradiscal pressures (IDPs) in an "air chamber disk model" representing intradiscal pressure. PSPs and IDPs were measured simultaneously while varying injection speeds, and using intrasyringeal and extrasyringeal pressure sensors and contrast medium-filled tubing of different lengths. All pressure/volume curves were collected and viewed dynamically, and stored for further analysis. RESULTS: At injection speed of 0.1 cc/second, the mean pressure difference (mean ΔP) between PSP and IDP was 38.1 psi. As injection speed was reduced, mean ΔP was proportionally decreased. Mean ΔP was 5.3 psi at injection speed of 0.01 cc/second and 0.7 psi at 0.005 cc/second. Mean ΔP values were significantly higher when pressures were recorded using intrasyringeal sensor: at injection speed of 0.1 cc/second, PSP and IDP values were 82.9 and 30.1 psi, respectively, compared with 50.6 and 12.5 psi measured by extrasyringeal sensor. Mean ΔP due to increased length of tubing was not significant. CONCLUSION: Discography can be better performed with low speed injection (≤0.01 cc/second), using an extrasyringeal sensor. Difference of length of connecting tubings did not cause significant pressure differences. These data suggest that automated discography is a helpful adjunct to improve diagnostic accuracy, due to extrasyringeal location of pressure sensor and greater control of injection speed.

Innovative Behavior in the Workplace: An Empirical Study of Moderated Mediation Model of Self-Efficacy, Perceived Organizational Support, and Leader-Member Exchange.

Recently, most organizations, from for-profit organizations to nonprofit organizations, are facing a rapidly changing environment and increased uncertainty. Organizational performance now depends on quickly responding and overcoming change through employees' innovative behavior. As the importance of innovative behavior has been highlighted, many organizations are looking for effective ways to encourage employees to adopt innovative behavior. From the resource perspective, innovative behavior can be regarded as high-intensity job demand, and organizations should support innovative behavior by providing and managing employees' resources. Based on the conservation of resource perspective, this study attempted to empirically explore how self-efficacy and perceived organizational support affect the relationship between leader-member exchange (LMX) and innovative behavior. Using two-wave, time-lagged survey data from 337 employees in South Korea, we found that leader-member exchange enhances innovative behavior via the mediation of self-efficacy. Additionally, perceived organizational support positively moderates the relationship between leader-member exchange and self-efficacy. Our findings demonstrate that self-efficacy is a mediating mechanism in the relationship between leader-member exchange and innovative behavior. Furthermore, this study suggests that the higher the level of perceived organizational support, the greater the effect of leader-member exchange on innovative behavior affected by self-efficacy.

Recent Advances in Synthesis, Properties, and Applications of Metal Halide Perovskite Nanocrystals/Polymer Nanocomposites.

Metal halide perovskite nanocrystals (PNCs) have recently garnered tremendous research interest due to their unique optoelectronic properties and promising applications in photovoltaics and optoelectronics. Metal halide PNCs can be combined with polymers to create nanocomposites that carry an array of advantageous characteristics. The polymer matrix can bestow stability, stretchability, and solution-processability while the PNCs maintain their size-, shape- and composition-dependent optoelectronic properties. As such, these nanocomposites possess great promise for next-generation displays, lighting, sensing, biomedical technologies, and energy conversion. The recent advances in metal halide PNC/polymer nanocomposites are summarized here. First, a variety of synthetic strategies for crafting PNC/polymer nanocomposites are discussed. Second, their array of intriguing properties is examined. Third, the broad range of applications of PNC/polymer nanocomposites is highlighted, including light-emitting diodes (LEDs), lasers, and scintillators. Finally, an outlook on future research directions and challenges in this rapidly evolving field are presented.

The C-type lectin CD209b is expressed on microglia and it mediates the uptake of capsular polysaccharides of Streptococcus pneumoniae.

Although Streptococcus pneumoniae is the major cause of meningitis, how it causes disease is poorly understood. The C-type lectin SIGN-R1 mediates the recently described SIGN-R1 complement activation pathway, which operates against capsular polysaccharides (CPSs) of S. pneumoniae in splenic marginal macrophages. Here, we demonstrate that SIGN-R1, as well as the rat SIGN-R1 homologue CD209b are expressed in most regions of mouse or rat brain, respectively. Moreover, both C-type lectins are obviously expressed on microglia, but not on neurons or astrocytes. We also found that rat CD209b mediates the uptake of dextran or CPS14 within the rat splenic marginal zone, similar to SIGN-R1. On microglia, rat CD209b also mediates the uptake of CPS14 of S. pneumoniae. Our findings strongly suggest that both rat CD209b and SIGN-R1 on microglia mediate the SIGN-R1 complement activation pathway against S. pneumoniae, and thereby plays an important role in the pathogenesis of pneumococcal meningitis.

SO2-Resistant Amine-Containing CO2 Adsorbent with a Surface Protection Layer.

Amine-containing solids are promising adsorbents for CO2 capture, but they suffer from irreversible poisoning by the highly acidic SO2 in flue gas. Here, we demonstrate a facile strategy to inhibit SO2 poisoning. We first prepared an amine-containing adsorbent by impregnating polyethyleneimine (PEI) into porous silica. The PEI located at the external surface of the adsorbent was selectively alkylated with epoxide so that amines were fully converted to tertiary amines. As opposed to that onto primary and secondary amines, SO2 adsorption onto tertiary amines is fully reversible. Therefore, during the flue gas adsorption, SO2 is reversibly captured by the tertiary-amine-rich layer and then desulfurized CO2 is adsorbed onto PEI beneath this layer. The resultant adsorbent showed insignificant loss of CO2 adsorption capacity (8.52%) even after 1000 CO2 adsorption-desorption cycles in the presence of 50 ppm SO2, whereas conventional PEI/silica showed severe capacity loss (65.1%) due to irreversible SO2 poisoning.

A novel approach to predicting human ingress motion using an artificial neural network.

Due to the increased availability of digital human models, the need for knowing human movement is important in product design process. If the human motion is derived rapidly as design parameters change, a developer could determine the optimal parameters. For example, the optimal design of the door panel of an automobile can be obtained for a human operator to conduct the easiest ingress and egress motion. However, acquiring motion data from existing methods provides only unrealistic motion or requires a great amount of time. This not only leads to an increased time consumption for a product development, but also causes inefficiency of the overall design process. To solve such problems, this research proposes an algorithm to rapidly and accurately predict full-body human motion using an artificial neural network (ANN) and a motion database, as the design parameters are varied. To achieve this goal, this study refers to the processes behind human motor learning procedures. According to the previous research, human generate new motion based on past motion experience when they encounter new environments. Based on this principle, we constructed a motion capture database. To construct the database, motion capture experiments were performed in various environments using an optical motion capture system. To generate full-body human motion using this data, a generalized regression neural network (GRNN) was used. The proposed algorithm not only guarantees rapid and accurate results but also overcomes the ambiguity of the human motion objective function, which has been pointed out as a limitation of optimization-based research. Statistical criteria were utilized to confirm the similarity between the generated motion and actual human motion. Our research provides the basis for a rapid motion prediction algorithm that can include a variety of environmental variables. This research contributes to an increase in the usability of digital human models, and it can be applied to various research fields.

Dominant role of splenic marginal zone lipid rafts in the classical complement pathway against S. pneumoniae.

Lipid rafts (LRs) play crucial roles in complex physiological processes, modulating innate and acquired immune responses to pathogens. The transmembrane C-type lectins human dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) and its mouse homolog SIGN-R1 are distributed in LRs and expressed on splenic marginal zone (MZ) macrophages. The DC-SIGN-C1q or SIGN-R1-C1q complex could mediate the immunoglobulin (Ig)-independent classical complement pathway against Streptococcus pneumoniae. Precise roles of LRs during this complement pathway are unknown. Here we show that LRs are indispensable for accelerating the DC-SIGN- or SIGN-R1-mediated classical complement pathway against S. pneumoniae, thus facilitating rapid clearance of the pathogen. The trimolecular complex of SIGN-R1-C1q-C4 was exclusively enriched in LRs of splenic MZ macrophages and their localization was essential for activating C3 catabolism and enhancing pneumococcal clearance, which were abolished in SIGN-R1-knockout mice. However, DC-SIGN replacement on splenic MZ macrophage's LRs of SIGN-R1-depleted mice reversed these defects. Disruption of LRs dramatically reduced pneumococcal uptake and decomposition. Additionally, DC- SIGN, C1q, C4, and C3 were obviously distributed in splenic LRs of cadavers. Therefore, LRs on splenic SIGN-R1+ or DC-SIGN+ macrophages could provide spatially confined and optimal bidirectional platforms, not only for usual intracellular events, for example recognition and phagocytosis of pathogens, but also an unusual extracellular event such as the complement system. These findings improve our understanding of the orchestrated roles of the spleen, unraveling a new innate immune system initiated from splenic MZ LRs, and yielding answers to several long-standing problems, including the need to understand the profound role of LRs in innate immunity, the need to identify how such a small portion of splenic SIGN-R1+ macrophages (<0.05% of splenic macrophages) effectively resist S. pneumoniae, and the need to understand how LRs can promote the protective function of DC-SIGN against S. pneumoniae in the human spleen.

Ginsenoside Rg3 inhibits human Kv1.4 channel currents by interacting with the Lys531 residue.

We have demonstrated previously that the 20(S) but not the 20(R) form of ginsenoside Rg(3) inhibited K(+) currents flowing through Kv1.4 (hKv1.4) channels expressed in Xenopus laevis oocytes, pointing to the presence of specific interaction site(s) for Rg(3) in the hKv1.4 channel. In the current study, we sought to identify this site(s). To this end, we first assessed how point mutations of various amino acid residues of the hKv1.4 channel affected inhibition by 20(S)-ginsenoside Rg(3) (Rg(3)). Lys531 residue is known to be a key site for K(+) activation and to be part of the extracellular tetraethylammonium (TEA) binding site; the mutation K531Y abolished the Rg(3) effect and made the Kv1.4 channel sensitive to TEA applied to the extracellular side of the membrane. Mutations of many other residues, including the pH sensitive-site (H507Q), were without any significant effect. We next examined whether K(+) and TEA could alter the effect of Rg(3) and vice versa. We found that 1) raising [K(+)](o) reduced the inhibitory effect of Rg(3) on hKv1.4 channel currents, whereas Rg(3) shifted the K(+) activation curve to the right, and 2) TEA caused a rightward shift of the Rg(3) concentration-response curve of wild-type hKv1.4 channel currents, whereas Rg(3) caused a rightward shift of the TEA concentration-response curve of K531Y mutant channel currents. The docked modeling revealed that Lys531 plays a key role in forming hydrogen bonds between Rg(3) and hKv1.4 channels. These results indicate that Rg(3) inhibits the hKv1.4 channel current by interacting with residue Lys531.

Rational Design of the Polymeric Amines in Solid Adsorbents for Postcombustion Carbon Dioxide Capture.

Substantial efforts have been made to increase the CO2 working capacity of amine adsorbents for an efficient CO2 capture. However, the more important metric for assessing adsorbents is the regeneration heat required for capturing a fixed amount of CO2. In this work, we synthesized polyethyleneimine (PEI)/SiO2 adsorbents functionalized with various epoxides. This provided adsorbents with six different amine structures showing various CO2/H2O adsorption properties. Our studies revealed that the CO2 working capacity was not a decisive factor in determining the regeneration heat required for CO2 capture. This is because the benefit of large CO2 working capacity was canceled out by the difficulty of CO2 desorption. Instead, the suppression of H2O co-adsorption was critical for reducing the regeneration heat because substantial latent heat is required for H2O desorption. Consequently, the PEI/SiO2 functionalized with 1,2-epoxybutane required a much lower regeneration heat (2.66 GJ tCO2-1) than the conventional PEI/SiO2 (4.03 GJ tCO2-1) because of suppressed H2O co-adsorption as well as moderately high CO2 working capacity.