Carbonate Linkages Research Articles

Mitigation effect of a biodegradable surfactant N,N,N-trimethyl-2-(((hexadecyloxy)carbonyl)oxy)ethan-1-aminiumiodide for mild steel corrosion in 5% HCl: Experimental and theoretical insights

A cleavable cationic surfactant having carbonate linkage, N,N,N-trimethyl-2-(((hexadecyloxy)carbonyl)oxy)ethan-1-aminiumiodide referred to as THC was synthesised and characterized employing elemental analysis, FT-IR (Fourier Transform Infrared Spectroscopy), 1H NMR (Nuclear Magnetic Resonance) and 13C NMR. The extent of corrosion inhibition of THC was for the first time studied experimentally and theoretically on mild steel (MS) substrate in 5 % HCl solution at temperatures 303, 313, 323, 333, 343, 353 K. Experimental investigations include gravimetric analysis, potentiodynamic polarization (PDP) and electrochemical impedance analysis (EIS). THC provided maximum inhibition efficiency of 93.2 % at concentration of 1×10−4 M at 303 K which was further raised to 98.1 % at 353 K. PDP studies reveal that given surfactant is mixed type inhibitor. Surface studies such as contact angle measurement, AFM (Atomic Force Microscopy), SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray Analysis), and XPS (X-ray Photoelectron Spectroscopy) were employed to justify the adsorption of inhibitor molecules on MS surface. Furthermore, biodegradability test on THC was done to support the environment friendly nature of the surfactant.

Fast, Regioselective Aminolysis of Tetrasubstituted Cyclic Carbonates and Application to Recyclable Thermoplastics and Thermosets.

Herein, the long-standing challenge of the ring-opening aminolysis of CO2-derived tetrasubstituted cyclic carbonates at room temperature (r.T) is overcome under catalyst-free conditions. Molecular design of the cyclic carbonate by substitution of an alkyl group by a thioether unlocks quantitative conversion at r.T and ensures total regioselectivity toward highly substituted oxazolidone scaffolds. An in-depth rationalization of the high reactivity of these cyclic carbonate structures and of the aminolysis reaction mechanism is provided by a computational study supporting experimental observations. The high efficiency of the reaction is then translated to the deconstruction of high-performance thermoplastics containing tetrasubstituted cyclic carbonate linkages to deliver building blocks that are reused for designing recyclable thermosets bearing dynamic N,S-acetal linkages.

Mononuclear phenoxy-imine Mg(II) compounds as catalysts for the ring-opening copolymerization of epoxides with CO2

The ring-opening copolymerization (ROCOP) of epoxides with CO2 is an efficient gateway for synthesizing sustainable aliphatic polycarbonates. The demand for the use of biocompatible metals for the copolymerization is an appealing research goal. The oxophilic Mg(II) has been employed as a metal center in homodinuclear and heterodinuclear catalyst frameworks. However, there is scarce literature involving mononuclear Mg(II) compounds. This work investigates the catalytic activity of two series of phenoxy-imine containing mononuclear Mg(II) compounds for the copolymerization studies of epoxides with CO2 in conjugation with cocatalyst tetraphenylphosphonium chloride (TPPCl). The two series of Mg(II) compounds differed from each other in the number of ancillary ligands attached to the Mg(II) center. The two epoxides employed for the study include cyclohexene oxide (CHO) and propylene oxide (PO). The catalytic activity of the disubstituted Mg(II) compounds was higher compared to monosubstituted compounds. In addition, the dependence of catalytic activity and percentage of carbonate linkage with the variation in the substituent of the phenolate core and imine side arm were studied. At 40 bar CO2 pressure and 80 °C, the catalyst exhibited carbonate linkage up to 97 % for ROCOP with cyclohexene oxide (CHO) with the percentage of the highest m-centered tetrad reaching up to 94 %. The mechanism for the ROCOP of CHO with CO2 is proposed based on kinetics studies and experimental data, which is further supported by density functional theory-based calculations.

Two‐Dimensional Silver–Isocyanide Frameworks

Metal‐organic frameworks (MOFs) have been widely studied due to their versatile applications and easily tunable structures. However, heteroatom‐metal coordination dominates the MOFs community, and the rational synthesis of carbon–metal coordination‐based MOFs remains a significant challenge. Herein, two‐dimensional (2D) MOFs based on silver–carbon linkages are synthesized through the coordination between silver(I) salt and isocyanide‐based monomers at ambient condition. The as‐synthesized 2D MOFs possess well‐defined crystalline structures and a staggered AB stacking mode. Most interestingly, these 2D MOFs, without π–π stacking between layers, exhibit narrow bandgaps down to 1.42 eV. As electrochemical catalysts for converting CO2 to CO, such 2D MOFs demonstrate Faradaic efficiency over 92%. Surprisingly, the CO2 reduction catalyzed by these MOFs indicates favorable adsorption of CO2 and *COOH on the active carbon sites of the isocyanide groups rather than on silver sites. This is attributed to the critical σ donor role of isocyanides and the corresponding ligand‐to‐metal charge–transfer effect. This work not only paves the way toward a new family of MOFs based on metal–isocyanide coordination but also offers a rare platform for understanding the electrocatalysis processes on strongly polarized carbon species.

Integrated crop management for long-term sustainability of maize-wheat rotation focusing on productivity, energy and carbon footprints

Modern agriculture, driven by diesel-fed machinery, is both energy and carbon-intensive, primarily due to the improper use of inputs. Designing a production module with lower carbon emissions, greater productivity, and enhanced energy use efficiency is crucial for achieving the environmental sustainability. Conservation agriculture based integrated crop management (ICMs) practices have shown promise in improving the productivity, energy-use, and reducing the carbon emissions. In our extensive long-term field study, we explored the crop yields, energy use, and carbon linkages of a maize-wheat rotation under different ICMs practices. Eight ICMs were evaluated over the course of nine consecutive years, which included ICM1&2: conventional (CT) flat-bed maize and wheat, ICM3&4: CT raised bed maize fb wheat without residues, ICM5&6: conservation agriculture (CA)-based double zero tilled (ZT) maize fb ZT wheat with residues and ICM7&8: CA-based triple ZT maize and wheat with residues and green manures. Our results indicated that the system productivity under CA-based ICMs was 16.5–22.9% greater than that under the CT-based ICM1-4. CA based ICM5-8 (125.2–131.5 × 103 MJ ha−1) needed higher energy input than CT-based ICM1-4 (32.7–39 × 103 MJ ha−1), with 76–80% shared by renewable crop residues. Furthermore, the CA-based ICMs recorded significantly higher levels of specific energy, human energy profitability, non-renewable energy use efficiency, and nutrient energy use efficiencies compared to CT-based. Likewise, the CA-based ICMs produced 12.5% more total output energy than the CT-based ICMs. In contrast, the CT based ICMs demonstrated, energy productivity, higher net energy returns and energy profitability. Compared to conventional ICMs, CA-based ICMs produced a 23–36% reduction in spatial carbon emissions and a 31–44 % reduction in yield-scale emissions. Nevertheless, the CA-based practices recorded the higher C- output, C- sustainability and C- efficiency ratio. Greenhouse gas intensity (GHGI) was 33.3–76.2% greater with the ICM1-4 practices than with the ICM5-8 practises. Thus, the present study proposed that adopting the integrated crop management practices based on the conservation agriculture could prove to be productive, as well as carbon and energy-use efficient approach for the maize-wheat rotation. This approach is envisioned to make substantial contributions to both food security and environmental sustainability.

Extreme precipitation reduces the recent photosynthetic carbon isotope signal detected in ecosystem respiration in an old-growth temperate forest.

The successful utilization of stable carbon isotope approaches in investigating forest carbon dynamics has relied on the assumption that the carbon isotope compositions (δ13C) therein have detectable temporal variations. However, interpreting the δ13C signal transfer can be challenging, given the complexities involved in disentangling the effect of a single environmental factor, the isotopic dilution effect from background CO2 and the lack of high-resolution δ13C measurements. In this study, we conducted continuous in situ monitoring of atmospheric CO2 (δ13Ca) across a canopy profile in an old-growth temperate forest in northeast China during the normal year 2020 and the wet year 2021. Both years exhibited similar temperature conditions in terms of both seasonal variations and annual averages. We tracked the natural carbon isotope composition from δ13Ca to photosynthate (δ13Cp) and to ecosystem respiration (δ13CReco). We observed significant differences in δ13Ca between the two years. Contrary to in 2020, in 2021 there was a δ13Ca valley in the middle of the growing season, attributed to surges in soil CO2 efflux induced by precipitation, while in 2020 values peaked during that period. Despite substantial and similar seasonal variations in canopy photosynthetic discrimination (Δ13Ccanopy) in the two years, the variability of δ13Cp in 2021 was significantly lower than in 2020, due to corresponding differences in δ13Ca. Furthermore, unlike in 2020, we found almost no changes in δ13CReco in 2021, which we ascribed to the imprint of the δ13Cp signal on above-ground respiration and, more importantly, to the contribution of stable δ13C signals from soil heterotrophic respired CO2. Our findings suggest that extreme precipitation can impede the detectability of recent photosynthetic δ13C signals in ecosystem respiration in forests, thus complicating the interpretation of above- and below-ground carbon linkage using δ13CReco. This study provides new insights for unravelling precipitation-related variations in forest carbon dynamics using stable isotope techniques.

Amino acid carbon isotope profiles provide insight into lability and origins of particulate organic matter

AbstractIdentifying the phytoplankton origin of particulate organic matter (POM) in the deep ocean is challenging due to the changing phytoplankton composition and varied extent of decomposition by heterotrophic bacteria and zooplankton. Here, we report vertical distributions of amino acid stable carbon isotope values (δ13C) measured in particles in the South China Sea. Carbon‐weighted amino acid δ13C values generally parallel bulk POM δ13C profiles with a positive offset from 2.4‰ in the surface water to 6.0‰ in deep. Accordingly, a lability model is introduced to describe the relative distribution and isotopic linkage of labile and refractory particulate organic carbon. Temporal changes of amino acid δ13C were observed during the microbial decomposition of two phytoplankton strains, the prokaryote cyanobacterium Synechococcus and the eukaryote diatom Thalassiosira weissflogii. Principal component analysis of individual amino acid δ13C values from the decomposing cells separate samples into two components, reflecting the influence of microbial decomposition and taxonomic differences, respectively. These two components were further applied to particles. A major contribution from decomposing phytoplankton to particles below the euphotic zone was observed, with more prokaryote organic matter in the basin and a larger contribution from eukaryotes at stations near the productive northern shelf. Our findings show the applicability of amino acid δ13C values in tracing the lability and phytoplankton origins of POM in samples with varied extents of decomposition in marine environments.

Controlled Carbon Dioxide Terpolymerizations to Deliver Toughened yet Recyclable Thermoplastics.

Using CO2 polycarbonates as engineering thermoplastics has been limited by their mechanical performances, particularly their brittleness. Poly(cyclohexene carbonate) (PCHC) has a high tensile strength (40 MPa) but is very brittle (elongation at break <3%), which limits both its processing and applications. Here, well-defined, high molar mass CO2 terpolymers are prepared from cyclohexene oxide (CHO), cyclopentene oxide (CPO), and CO2 by using a Zn(II)Mg(II) catalyst. In the catalysis, CHO and CPO show reactivity ratios of 1.53 and 0.08 with CO2, respectively; as such, the terpolymers have gradient structures. The poly(cyclohexene carbonate)-grad-poly(cyclopentene carbonate) (PCHC-grad-PCPC) have high molar masses (86 < Mn < 164 kg mol-1, ĐM < 1.22) and good thermal stability (Td > 250 °C). All the polymers are amorphous with a single, high glass transition temperature (96 < Tg < 108 °C). The polymer entanglement molar masses, determined using dynamic mechanical analyses, range from 4 < Me < 23 kg mol-1 depending on the polymer composition (PCHC:PCPC). These polymers show superior mechanical performance to PCHC; specifically the lead material (PCHC0.28-grad-PCPC0.72) shows 25% greater tensile strength and 160% higher tensile toughness. These new plastics are recycled, using cycles of reprocessing by compression molding (150 °C, 1.2 ton m-2, 60 min), four times without any loss in mechanical properties. They are also efficiently chemically recycled to selectively yield the two epoxide monomers, CHO and CPO, as well as carbon dioxide, with high activity (TOF = 270-1653 h-1, 140 °C, 120 min). The isolated recycled monomers are repolymerized to form thermoplastic showing the same material properties. The findings highlight the benefits of the terpolymer strategy to deliver thermoplastics combining the beneficial low entanglement molar mass, high glass transition temperatures, and tensile strengths; PCHC properties are significantly improved by incorporating small quantities (23 mol %) of cyclopentene carbonate linkages. The general strategy of designing terpolymers to include chain segments of low entanglement molar mass may help to toughen other brittle and renewably sourced plastics.

Recent Advances in the Direct N–C(sp2) Nitrone Synthesis from Oxime

Nitrones are pivotal in organic chemistry, especially for the synthesis of natural and biologically active compounds via 1,3‐dipolar cycloadditions and Kinugasa reactions. Although numerous methods have been reported for the synthesis of nitrones with an sp3 carbon connected to a nitrogen atom, the development of nitrones with an sp2 carbon linkage, including N‐vinyl, N‐aryl, and N‐alkoxycarbonyl nitrones, remains relatively underexplored. This review summarizes the current research trends and methodologies for the direct synthesis of nitrones, in which an sp2 carbon is directly bonded to a nitrogen atom, beginning with oximes.

Bioreducible Amphiphilic Hyperbranched Polymer-Drug Conjugate for Intracellular Drug Delivery.

This paper reports synthesis of a bioreducible hyperbranched (HB) polymer by A2+B3 approach from commercially available dithiothreitol (DTT) (A2) and an easily accessible trifunctional monomer (B3) containing three reactive pyridyl-disulfide groups. Highly efficient thiol-activated disulfide exchange reaction leads to the formation of the HB polymer (Mw = 21000; Đ = 2.3) with bioreducible disulfide linkages in the backbone and two different functional groups, namely, hydroxyl and pyridyl-disulfide in the core and periphery, respectively, of the HB-polymer. Postpolymerization functionalization of the hydroxyl-groups with camptothecin (CPT), a topoisomerase inhibitor and known anticancer drug, followed by replacing the terminal pyridyl-disulfide groups with oligo-oxyethylene-thiol resulted in easy access to an amphiphilic HB polydisulfide-CPT conjugate (P1) with a very high drug loading content of ∼40%. P1 aggregated in water (above ∼10 μg/mL) producing drug-loaded nanoparticles (Dh ∼ 135 nm), which showed highly efficient glutathione (GSH)-triggered release of the active CPT. Mass spectrometry analysis of the GSH-treated P1 showed the presence of the active CPT drug as well as a cyclic monothiocarbonate product, which underpins the cascade-degradation mechanism involving GSH-triggered cleavage of the labile disulfide linkage, followed by intramolecular nucleophilic attack by the in situ generated thiol to the neighboring carbonate linkage, resulting in release of the active CPT drug. The P1 nanoparticle showed excellent cellular uptake as tested by confocal fluorescence microscopy in HeLa cells by predominantly endocytosis mechanism, resulting in highly efficient cell killing (IC50 ∼ 0.6 μg/mL) as evident from the results of the MTT assay, as well as the apoptosis assay. Comparative studies with an analogous linear polymer-CPT conjugate showed much superior intracellular drug delivery potency of the hyperbranched polymer.

A mechanochemical approach to recycle thermosets containing carbonate and thiourethane linkages

Over the past decades, various industries shifted from traditional materials such as glass and metals to thermoset polymers due to their excellent chemical resistance, thermal stability, reduced weight, and affordability. However, at the end of their life cycle, these highly crosslinked polymers end up as environmental pollutants due to their non-recyclability. To tackle this issue, researchers are exploring vitrimer-type polymers with recyclable qualities, supporting a circular economy and sustainable management of thermoset wastes. This study investigates a new promising method of recycling two commonly used thermosets in commercial applications, poly allyl diglycol carbonate (PADC) and poly thiourethane (PTU), via a mechanochemical process known as vitrimerization. The process involves the cryogenic ball milling of the thermoset with a zinc-based catalyst and a hydroxyl-providing agent, followed by compression molding, enabling the thermoset conversion into a vitrimer. Rheological tests revealed the remarkable stress-relaxation capabilities of the vitrimerized networks, indicating the conversion of the initial permanent crosslinked structures into dynamic networks through vitrimerization. Dynamic mechanical analysis results show that the vitrimerized samples display a consistent rubbery plateau at high temperature, similar to that of permanently crosslinked networks, suggesting a fix crosslink density during the exchange reaction. Differential scanning calorimetry and thermogravimetric analysis results showed that the thermal properties of the vitrimerized samples closely resemble those of the original samples.

A proof-of-concept study on a fully biobased and degradable polymer network based on vanillin and myrcene

A vanillin monomer featuring a carbonate linkage in its center was synthesized and used to prepare degradable biobased polymer networks.

Forest diversity and aboveground carbon linkage between the national park and community managed tropical forests of Nepal

The relationship of forest diversity and aboveground carbon has been poorly explored in tropical forests under different management regimes. An assessment of the linkage between forest diversity and carbon has become important, particularly to devise effective approaches to forest management and policy formulation. To assess the relation between forest diversity and carbon stock, we correlated the structural attributes (i.e., DBH, height, wood density, and stem density), diversity attributes (i.e., species richness, Shannon Weiner index and Shannon equitability index) and aboveground carbon of tree species ≥ 5cm in DBH from Bardia National Park and adjoining Buffer zone Community Forest. Our results showed that most structural attributes are correlated to aboveground carbon in both forest types. While the diversity attributes (i.e., species richness and Shannon index) and stem density had no relation with aboveground carbon in both forests. Similarly, species evenness had a significant inverse relation with aboveground carbon in both forests. The correlation of DBH and height was stronger with aboveground carbon in community managed forest while the same was moderate in national park. In addition, the carbon stock was found slightly higher in the community managed forest than in national park. This indicates that forest structural diversity enhances the aboveground carbon in tropical forests, and community managed forest promotes the better growth of vegetation. These results provide a better insight into forest management and its effects on forest diversity and aboveground carbon.

Fluorinated Graphene Fillers for High-Performance Solid-State Lithium Batteries

Solid-state batteries (SSBs) are expected to revolutionize the field of energy storage due to their superior safety and high energy density, which result from the use of lithium metal as the negative electrode. However, the development of solid-state electrolytes (SSEs), the key component of SSBs, is quite crucial. SSEs have high thermal stability, high mechanical strength, and a wide electrochemical window but lack enough ionic conductivity; which is one of the most challenging aspects. Incorporating suitable active or inert fillers in the solid polymer electrolyte matrix is one of several methods adopted to improve the ionic conductivity of pure polymer SSEs. Two-dimensional graphene-based fillers are a promising option as they provide a high surface area for creating an abundant interface with the polymer matrix creating a continuous pathway for lithium-ion transport and simultaneously their robust nature improves the mechanical strength of the electrolyte. Pristine graphene is electronically conducting in nature owing to the continuous sp2 carbon linkages, but the electronic conductivity can be suppressed by disrupting the sp2 bonds by heteroatom functionalization on the graphene. This study investigates the heteroatom functionalization of graphene to obtain various graphene-based fillers such as graphene oxide (GO), reduced graphene oxide (rGO), and fluorinated graphene oxide (FGO) and their effectiveness when introduced into a polymer SSE matrix for LiNi0.8Co0.1Mn0.1O2-based SSBs. FGO filler outperforms others in terms of ionic conductivity, thermal stability, enhanced electrochemical potential window, and compatibility of the SSE. The optimized ratio of FGO fillers in SSE demonstrates excellent electrochemical performance, enabling long-term Li plating/stripping with small overpotential and stable cycling of Li/ LiNi0.8Co0.1Mn0.1O2 full cells. This work highlights the notable potential of FGO materials in improving the comprehensive properties of polymer SSEs and promoting the applications of polymer SSEs in high-performance SSBs.

Highly efficient CO2 and propylene oxide co-polymerization using Zn glutarate/Zn-Cr double metal cyanide composite catalyst

A highly active zinc glutarate-double metal cyanide (DMC) composite catalyst (ZnGA/Zn-CrDMC) was designed for the carbon dioxide (CO2) and propylene oxide (PO) copolymerization reaction. The composite catalyst was synthesized in a rheological phase reaction and characterized using Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The synthesized composite catalysed the solvent free reactions of PO and CO2 to afford biodegradable polypropylene carbonate (PPC) copolymer. 1H NMR,13C NMR, FT-IR and ESI-TOF mass spectrometry measurements were employed to confirm the characteristics of the PPC produced. Under optimal reaction conditions (50 bar CO2, 70 °C, 24 h), the ZnGA-Zn3[Cr(CN)6]2 composite displayed higher catalytic activities in the copolymerization reactions than the individual catalysts. The ZnGA:Zn3[Cr(CN)6]2 ratio of 15:1 gave PPC yield of 47.9 g polymer/g cat compared to ZnGA that produced 42.6 g polymer/ g cat in 24 h. In addition, the PPC produced from the composite catalyst displayed higher carbonate linkage content (Fc = 85.4 %) compared to the value of Fc = 33.9 %. obtained using the Zn3[Cr(CN)6]2 catalyst. Similaly, the composite catalsyt produced PPC with molecular weight of 4200 g/mol and narrow polydispersity index of 2.2. The resultant PPC copolymer displayed good thermal stability, exhibiting a high degradation temperatures (TGA-10%) of 229 °C and complete decomposition at 350 °C.

Click to Self‐immolation: A “Click” Functionalization Strategy towards Triggerable Self‐Immolative Homopolymers and Block Copolymers

AbstractSelf‐immolative polymers (SIPs) are a class of degradable macromolecules that undergo stimuli‐triggered head‐to‐tail depolymerization. However, a general approach to readily end‐functionalize SIP precursors for programmed degradation remains elusive, restricting access to complex, functional SIP‐based materials. Here we present a “click to self‐immolation” strategy based on aroyl azide‐capped SIP precursors, enabling the facile construction of diverse SIPs with different trigger units through a Curtius rearrangement and alcohol/thiol‐isocyanate “click” reaction. This strategy is also applied to polymer‐polymer coupling to access fully depolymerizable block copolymer amphiphiles, even combining different SIP backbones. Our results demonstrate that the depolymerization can be actuated efficiently under physiologically‐relevant conditions by the removal of the trigger units and ensuing self‐immolation of the p‐aminobenzyl carbonate linkage, indicating promise for controlled release applications involving nanoparticles and hydrogels.

Click to Self-immolation: A "Click" Functionalization Strategy towards Triggerable Self-Immolative Homopolymers and Block Copolymers.

Self-immolative polymers (SIPs) are a class of degradable macromolecules that undergo stimuli-triggered head-to-tail depolymerization. However, a general approach to readily end-functionalize SIP precursors for programmed degradation remains elusive, restricting access to complex, functional SIP-based materials. Here we present a "click to self-immolation" strategy based on aroyl azide-capped SIP precursors, enabling the facile construction of diverse SIPs with different trigger units through a Curtius rearrangement and alcohol/thiol-isocyanate "click" reaction. This strategy is also applied to polymer-polymer coupling to access fully depolymerizable block copolymer amphiphiles, even combining different SIP backbones. Our results demonstrate that the depolymerization can be actuated efficiently under physiologically-relevant conditions by the removal of the trigger units and ensuing self-immolation of the p-aminobenzyl carbonate linkage, indicating promise for controlled release applications involving nanoparticles and hydrogels.

Dual responsive cellulose-based fluorescent material fabricated in a CO2 switchable solvent for multifunctional applications

Fabrication of multi-responsive fluorescent sensors for real-time and visual monitoring or detection is practical and challenging. Herein, a novel cellulose-based fluorescent functional material with dual-responsive properties arising from two different functional sites was successfully designed and prepared in a CO2 switchable solvent. Cellulose was effectively dissolved in this solvent and easily functionalized by successively grafting poly (lactic acid) and 7-hydroxy-4-trifluoromethyl coumarin (HFC) onto the cellulose backbone, resulting in C-g-PLLA/HFC with good processibility and fluorescence quenching response (turn off) towards Fe3+ due to the coordination of Fe3+ with the carbonate linkage. Acetylation of HFC under microwave-assisted conditions gave rise to C-g-PLLA/HFC-Ac which showed fluorescence enhancement response (turn on) to various organic amines because of the removal of the acetyl group by aminolysis reaction. Therefore, they could be respectively used for selective identification and detection of Fe3+, and real-time, accurate and visual monitoring of aquatic product freshness. Furthermore, an interesting application for irreversible information encryption was demonstrated by combining the dual-responsive property. This study suggests a new strategy for constructing cellulose-based functional material with multiple responsiveness and applications.

Cholesterol based mesogenic Schiff’s base derivatives with carbonate linkage: Synthesis, characterisation and photoluminescence study

ABSTRACT The steroidal derivatives have been found to be extremely good mesogens since their origin. Due to their inherent chirality, they have the potential to induce a wide variety of liquid crystalline phases, including frustrated phases, depending on the structure of the steroidal skeleton and the substituents attached. In this report, thirteen new homologous Schiff’s base derivatives were synthesised by condensing 4-n-alkoxy aniline with 4-formyl phenyl cholesteryl carbonate. All the compounds were characterised using elemental analysis, FT-IR, 1H-NMR and 13C-NMR. In order to study the liquid crystalline behaviour of the synthesised compounds, optical texture studies were carried out using polarising optical microscope in heating and cooling cycles. The derivatives showed a variety of mesophases, including chiral nematic (N*), twist grain boundary-A (TGBA), smectic A (SmA) and chiral smectic C (SmC*) phases. The thermal behaviour was determined using a differential scanning calorimeter and thermogravimetric analysis. All the synthesised compounds are UV-active and show photoluminescence in the blue emission region with good quantum yield.

Degradation of modified polystyrenes having degradable units by near‐infrared light irradiation

AbstractModified polystyrenes having tertiary ether linkages or carbonate linkages were degrade by irradiation of near‐infrared light (NIR) and subsequent heating. The polymer films containing a photoacid generator and commercially available photon upconversion nanoparticle (UCNP) were decomposed to form isobutene and/or carbon dioxide by irradiation of NIR and subsequent heating. The thermal decomposition behaviors of the polymers were investigated and discussed in terms of the chemical structures of degradable units. The thermal stability of the polymers was found to be in the order: tertiary ester &gt; tertiary carbonate. We believe that the degradation of NIR and subsequent heating contributes easy recycling of composite materials.