Polymeric Amine Research Articles

Comparative Ecotoxicity Assessment of highly bioactive Isomeric monoterpenes carvacrol and thymol on aquatic and edaphic indicators and communities

The growing demand for sustainable natural products to replace harmful synthetic ones requires comprehensive ecotoxicity assessments to ensure their eco-friendly nature. This study explored for the first time the changes in microbial community growth and metabolic profiles from river and natural soil samples exposed to the two structural isomers, thymol (THY) and carvacrol (CARV), utilizing Biolog EcoPlate™ assays and 16S rRNA gene sequencing for taxonomic analysis. In addition, we addressed existing ecotoxicity data gaps for these two compounds by using aquatic (Daphnia magna and Vibrio fischeri) and soil (Eisenia fetida and Allium cepa) indicators. Results show acute toxicity of both CARV and THY on all indicators. V. fischeri (LC50=0.59 mg/L) >D. magna (4.75 mg/L) >A. cepa (6.47 mg/L) for CARV, and V. fischeri (LC50=1.71 mg/L) >A. cepa (4.05 mg/L) >D. magna (8.13 mg/L) for THY. E. fetida showed LC50 = 7.68 mg/Kg for THY and 1.04 for CARV. River and soil microbial communities showed resilience, likely because they contain taxa capable of biodegrading these products. No significant growth inhibition effects were observed up to 100 mg/L, though substrate utilization decreased at higher concentrations, particularly for polymers and amines in soil microorganisms and polymers in aquatic communities. Soil microorganisms were more affected than aquatic ones, with CARV being more toxic than THY (EC50120h = THY 94.13 and CARV 29.79 mg/L in soil microorganisms). These findings suggest that an increase in the consumption of these products and their subsequent ecotoxicity effects from environmental discharge should still be monitored before being ruled out. However, long-term effects are unlikely due to microbial degradation of these natural products, potentially reducing risks to other target species and opening the way for their use as substitutes for commercial antibiotics.

Constructing Sulfur‐Heterocyclic Aromatic Amine Polymer with Multiple‐Redox Active Sites for Long‐Lifespan and All‐Organic Aqueous Magnesium Ion Batteries

AbstractOrganic polymer materials have attracted much attention in rechargeable aqueous magnesium ion batteries (AMIBs) due to their sustainability and structural designability. However, the ionic storage capability is hindered by their insufficient redox‐active sites, dissolvability in aqueous electrolytes, and short‐range conjugated structures, resulting in low energy density and poor cycling stability. Herein, a sulfur‐heterocyclic aromatic polyimide‐based organic polymer (PTDBS) is constructed with multiple redox‐active sites and long‐range conjugate, which is employed as active material for AMIB anode, achieving an outstanding Mg2+ storage capability. Benefitting from the introduced thioether bonds, PTDBS possesses an enhanced electronic conductivity and additional redox‐active sites for reversible Mg2+ coordination, thus ensuring high redox activity and superior electron affinity. As a result, the PTDBS electrode delivers ultrafast and stable Mg2+ storage in an MgCl2 aqueous electrolyte with a superior rate capacity of 98.6 mA h g−1 at 10.0 A g−1, and remarkable cycling stability over 7500 cycles with a capacity retention rate of 90.0%. Notably, the all‐organic aqueous full cell, realized by coupling the PTDBS anode and the polyindole cathode, achieves a high energy density and long lifespan. This work lays the foundation for the development of highly stable all‐organic electrode materials for large‐scale aqueous energy storage.

Synthesis and properties of oligopropylamines with photosensitive o-nitrobenzyl ester core

The o-nitrobenzyl ester group is known for more than 50 years as a convenient protecting group and fragment for the design of photosensitive systems, including drug delivery agents. Polymeric amines with these groups are promising systems for medical applications, but the lack of basic knowledge about the possible degradation of these compounds under physiological conditions restrains the development of real preparations. We synthesized five new polyamines with the insertion of the o-nitrobenzyl ester group into the chain, including an oligomeric mixture with a weight average number of amine groups equal to 21. The ester group in the polyamine chain was found to be sensitive to hydrolysis at neutral and alkaline pH values. The presence of an amine group near the ester group facilitates hydrolysis through coordination with a hydroxyl ion or water molecule. The catalytic action of the amine moieties is prevented by protonation of the amine at low pH values or by interaction with polymeric acid. The study of photodegradation of new polyamines by HPLC-MS showed the formation of a number of products, most of which were not considered in previous works with o-nitrobenzyl ester derivatives. The o-nitrobenzyl ester group is used in the design of gene delivery systems and other biomedical preparations as a fragment that can be degraded by light. Our results indicate that photodegradation of o-nitrobenzyl esters can produce a number of compounds whose structure and safety for living organisms must be evaluated before use. On the other hand, the discovered hydrolyzability of o-nitrobenzyl esters catalyzed by a neighboring amine group may find application in the development of drug delivery systems. We have shown that the lifetime of o-nitrobenzyl ester containing polyamines is sufficient for gene delivery. Self-degradation of the delivery agent after penetration into a living cell is a desirable case for the release of the delivered agent.

Synthesis and characterization of amine-functionalized graphene as a nitric oxide-generating coating for vascular stents.

Drug-eluting stents are commonly utilized for the treatment of coronary artery disease, where they maintain vessel patency and prevent restenosis. However, problems with prolonged vascular healing, late thrombosis, and neoatherosclerosis persist; these could potentially be addressed via the local generation of nitric oxide (NO) from endogenous substrates. Herein, we develop amine-functionalized graphene as a NO-generating coating on polylactic acid (PLA)-based bioresorbable stent materials. A novel catalyst was synthesized consisting of polyethyleneimine and polyethylene glycol bonded to graphene oxide (PEI-PEG@GO), with physicochemical characterization using x-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. In the presence of 10 μM S-nitrosoglutathione (GSNO) or S-nitroso-N-acetylpenicillamine (SNAP), PEI-PEG@GO catalyzed the generation of 62% and 91% of the available NO, respectively. Furthermore, PEI-PEG@GO enhanced and prolonged real-time NO generation from GSNO and SNAP under physiological conditions. The uniform coating of PEI-PEG@GO onto stent material is demonstrated via an optimized simple dip-coating method. The coated PLA maintains good biodegradability under accelerated degradation testing, while the PEI-PEG@GO coating remains largely intact. Finally, the stability of the coating was demonstrated at room temperature over 60 days. In conclusion, the innovative conjugation of polymeric amines with graphene can catalyze the generation of NO from S-nitrosothiols at physiologically relevant concentrations. This approach paves the way for the development of controlled NO-generating coatings on bioresorbable stents in order to improve outcomes in coronary artery disease.

Efficient recovery and recycling/upcycling of precious metals using hydrazide-functionalized star-shaped polymers

There is a growing demand for adsorption technologies for recovering and recycling precious metals (PMs) in various industries. Unfortunately, amine-functionalized polymers widely used as metal adsorbents are ineffective at recovering PMs owing to their unsatisfactory PM adsorption performance. Herein, a star-shaped, hydrazide-functionalized polymer (S-PAcH) is proposed as a readily recoverable standalone adsorbent with high PM adsorption performance. The compact chain structure of S-PAcH containing numerous hydrazide groups with strong reducibility promotes PM adsorption by enhancing PM reduction while forming large, collectable precipitates. Compared with previously reported PM adsorbents, commercial amine polymers, and reducing agents, S-PAcH exhibited significantly higher adsorption capacity, selectivity, and kinetics toward three PMs (gold, palladium, and platinum) with model, simulated, and real-world feed solutions. The superior PM recovery performance of S-PAcH was attributed to its strong reduction capability combined with its chemisorption mechanism. Moreover, PM-adsorbed S-PAcH could be refined into high-purity PMs via calcination, directly utilized (upcycled) as catalysts for dye reduction, or regenerated for reuse, demonstrating its high practical feasibility. Our proposed PM adsorbents would have a tremendous impact on various industrial sectors from the perspectives of environmental protection and sustainable development.

Poly[Bis(4‐Phenyl)(2,4,6‐Trimethylphenyl)Amine] in Perovskite Solar Cells: Advances via Molecular Engineering

To improve the performance of perovskite solar cells (PSCs), studying the materials that constitute each layer of the device is important. Among the commonly used materials in the hole‐transport layer (HTL), poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA) stands out as one of the most employed. This hole‐transport material (HTM) offers many advantages, including thin‐film fabricating feasibility, ease of synthesis, and sufficient energy levels. Further, PSCs employing PTAA as the HTL exhibit a high‐power conversion efficiency. However, it has some drawbacks, including low crystallinity and poor device stability. To overcome these limitations, extensive studies focusing on improving its properties by molecular engineering have been conducted. In this review, the strategies for engineering the molecular structures of triaryl amine polymers are introduced. The strategies are classified into three groups: backbone engineering, side‐chain substitution, and a combination of both. Furthermore, future directions for achieving HTMs with various properties for high‐performance PSCs are suggested.

Water-Soluble Quantum Dots for Inkjet Printing Color Conversion Films with Simultaneous High Efficiency and Stability.

Water-soluble quantum dots (QDs) are necessary to prepare patterned pixels or films for high-resolution displays with less environmental burden but are very limited by the trade-off between photoluminescence and stability of QDs. In this work, we proposed synthesizing water-soluble QDs with simultaneous excellent luminescence properties and high stability by coating the amphiphilic poly(maleic anhydride-alt-1-octadecene)-ethanol amine (PMAO-EA) polymer on the surface of silane-treated QDs. These coated QDs show a photoluminescence quantum yield (PLQY) as high as 94%, and they have good photoluminescence stability against light irradiation and thermal attacks, owing to the suppression of the nonradiative recombination by the polymer layer and the isolation of oxygen and water by the silica layer. The water-soluble QDs, mixed with ethylene glycol, enable inkjet printing of QD color conversion films (QD-CCFs) with an average diameter of 68 μm for each pixel and a high PLQY of 91%. The QD-CCFs are demonstrated to fabricate red-emitting mini-LEDs by combining with blue mini-LED chips, which have an external quantum efficiency as high as 25.86% and a luminance of 2.44 × 107 cd/m2. We believe that the proposed strategy is applicable to other water-soluble QDs and paves an avenue for inkjet printing environmentally friendly QD-CCFs for mini/micro-LED displays.

Quinone-amine polymers prepared by simple precipitation polymerization and used as cathodes for aqueous zinc-ion batteries and electrochromic materials

Quinone amine polymers with multiple active sites exhibit excellent performance in aqueous zinc ion batteries and as electrochromic materials.

Vapor-phase postsynthetic amination of hypercrosslinked polymers for efficient iodine capture

Hypercrosslinked polymers (HCPs) with large surface areas, high intrinsic porosities and low production costs may be available platforms for iodine capture. However, the lack of iodine-philicity binding sites limits their adsorption capacity. Here we use vapor-phase postsynthetic amination strategy to introduce electron-donating amino groups into the prefabricated HCPs for enhancing their iodine capture performance. Through simple vapor-phase exposure, the halogen-containing HCPs can be grafted by amines through nucleophilic substitution toward chloro groups. Combining with the abundant amino groups and high porosities, the amino-functionalized porous polymers show substantially increased iodine adsorption capacity, about 221% as that of original one, accompanied by excellent recyclability. Mechanism investigations reveal the key roles of the electron-donor amino groups and π-conjugated benzene rings along with structure characteristics of porous polymer frameworks in iodine capture. Moreover, this vapor-phase amination strategy shows good generality and can be extended to various amines, e.g., ethylenediamine, 1,3-diaminopropane and diethylenetriamine. Our work proves that this simple vapor-phase postsynthetic functionalization strategy may be applied in other porous polymers with wide application prospects in adsorption, separation and storage.

Synthesis, Performance, Mechanism: A Hyperbranched Phase Reverse Nano-Demulsifier for Condensate Emulsion

Organic amine and nanosilica were combined to create a nano-demulsifier, which was employed in the oil–water separation process of a condensate emulsion. The nano-demulsifier has the structure of hyperbranched polymers and the skeleton structure of hyperbranched nanomaterials, and displays the demulsification impact of organic amine polymers as well as the synergistic effect of nanomaterials. This nano-demulsifier has the potential to drastically reduce the quantity of condensate demulsifiers utilized in the gathering station. The dehydration rate of the condensate lotion in the gas gathering station can reach more than 95% only at a concentration of 1.0 wt.%. Its application can significantly increase the separation efficiency of the condensate emulsion as well as the quality of condensate oil. It has a positive impact on cost reduction and efficiency in gas well production. The mechanism of action of the demulsifier was also studied, and the results show that the demulsifier is a phase reverse demulsifier.

Developing High-Capacity Solid "Molecular Basket" Sorbents for Selective CO2 Capture and Separation.

ConspectusSince carbon-based energy continues to dominate (over 80%) the global primary energy supply, carbon dioxide capture, utilization, and sequestration (CCUS) is deemed to be a promising and viable option to mitigate greenhouse gas emissions and climate change, for which CO2 capture is critical to the overall success of CCUS. Although liquid amine scrubbing is a mature technology for carbon capture, it is energy-intensive and costly due to energy consumption in solvent heating and water evaporation apart from the energy needed to break amine-CO2 bonding. To address this challenge, Song's group developed a new design approach for adsorptive CO2 capture and separation, namely, "molecular basket" sorbents (MBS), without the need for dealing with solvent heating and water evaporation. The solid MBS consisting of polymeric amines (such as PEI) immobilized into nanoporous materials (such as SBA-15) possesses a high capacity for CO2 capture with high selectivity, fast kinetics, and good regenerability. Consequently, MBS can greatly reduce energy consumption and carbon capture cost. Conventional adsorbents such as zeolites, activated carbon, alumina, and silica have low adsorption capacities, and their use of CO2 adsorption requires prior removal of moisture and cooling of flue gas (∼35 °C). On the contrast, the CO2 sorption capacity of MBS can even be promoted by the presence of moisture/steam and reaches the best performance closer to flue gas temperature (∼75 °C). This Account presents an overview of our research progress in the material development and fundamental understanding of MBS for CO2 capture and the separation of CO2 from various gas streams. It begins with an illustration of the MBS concept, followed by efforts to improve the performance and pilot-scale demonstration of MBS for CO2 capture. With the systematic characterization of MBS by various ex situ and in situ techniques, a better understanding is developed for the CO2 sorption process mechanistically. Furthermore, this Account demonstrates how the fundamental understanding of the CO2 sorption mechanism promotes the further development of more robust and advanced sorbent materials with improved CO2 sorption capacity, kinetics of sorption and desorption, and cyclic stability. Finally, an outlook is provided for the future design and development of novel sorbent materials and the CO2 sorption process for various gas streams including flue gas, biogas, air, and hydrogen streams.

Polymeric carbon quantum dots as efficient chlorophyll sensor-analysis based on experimental and computational investigation

This report introduces a microfiber chlorophyll sensor based on polymeric amine functionalized carbon quantum dots (NCQD) using the surface plasmon resonance technique. The silver (Ag) thin film, followed by NCQD-polyvinyl alcohol composite film, was deposited on the tapered optical fiber. The characterization of surface morphologies of NCQD-PVA film using a field emission scanning electron microscope shows that the contact area with the analyte was well covered with Ag and NCQD-PVA. The experimental results show that the fiber optic SPR sensor can detect chlorophyll in the 0.01–2.0 ppm range with a high sensitivity response and a detection limit of 1.90 nm ppm−1 and 0.78 ppm, respectively. This study observed no significant interference among the other ionic species (Fe3+, NH4+, NO3–, NO2–, and PO4-) due to the electrostatic and π-π interactions between NCQD and chlorophyll. Results from density functional theory calculation also confirm that the interaction of the NCQD with chlorophyll existed, and the strongest interaction occurs between nitrogen at pyridine sites of the carbon core and the oxygen group of chlorophyll. The proposed NCQD/PVA optical fiber sensor exhibits good sensing performance and correlates well with the standard method (R2 = 0.9501), suggesting a suitable technology candidate for real-time environmental monitoring applications.

Chromaticity sensor for discriminatory identification of aliphatic and aromatic primary amines based on conformational changes of polyacetylene

The design and construction of suitable sensors that can selectively recognize chemically similar substances such as aliphatic and aromatic amines remain challenging. In this work, we reported a poly(phenylacetylene) bearing two aldehyde pendants as the color indicator for discriminative identification of amines. Reversible Schiff-base reaction of the aldehyde group with the amine resulted in a conformational transition of the polyacetylene backbone from cis-cisoid to cis-transoid, which further achieved a colorimetric change. Thirteen aliphatic amines and aromatic amines had been studied. Compared with aromatic amines, aliphatic amines generally caused the polyene backbone to display perceivable colorimetric change. Steric and electronic effect played a significant role in the colorimetric response. In addition, external environment, including amine content, polymer concentration, and temperature, had influence on the sensitivity of this colorimetric indicator system. The amines-induced colorimetric variation was further demonstrated by the CIELAB color space. Moreover, the colorimetric sensor exhibited excellent reversibility and recyclability.

Design of Amine-Containing Nanoporous Materials for Postcombustion CO2 Capture from Engineering Perspectives.

ConspectusCarbon dioxide (CO2) capture and storage (CCS) is a means to enable the continued use of fossil fuels in the short term. In particular, postcombustion CO2 capture has attracted considerable attention because it can be retrofitted into existing power plants and industrial plants. Among various CO2 capture technologies, the absorption of CO2 using aqueous amines has been industrially employed for decades. However, such amine scrubbing technologies have inherent limitations of environmental and health concerns due to volatile amine loss, corrosion, and high energy demands for regeneration. To overcome these limitations, CO2 adsorption using solid adsorbents has emerged as a promising alternative due to its noncorrosiveness and low energy demand. Various amine-containing adsorbents have been synthesized and investigated for postcombustion CO2 capture. These materials are prepared by physically impregnating low-vapor-pressure amine polymers or by chemically grafting amines onto nanoporous materials. A wide variety of amine guests and nanoporous hosts (e.g., SiO2, Al2O3, zeolites, MOFs, and polymers) have been combined to develop advanced CO2 adsorbents.The design of CO2 adsorbents is a multifaceted puzzle that must ultimately consider integration with large-scale CO2 capture processes. Various engineering aspects need to be carefully considered. Unfortunately, a significant proportion of previous studies has primarily focused on the use of novel materials for improving the CO2 adsorption capacity. In this Account, we describe key challenges and solutions to develop energy-efficient and stable amine-containing adsorbents for postcombustion CO2 capture via temperature swing adsorption (TSA). We found that a high CO2 working capacity, often overemphasized in the literature, does not necessarily guarantee a low energy demand for CO2 capture. Suppressing coadsorption of H2O during the CO2 adsorption in humid flue gas is also a significant factor. Amine-containing adsorbents can be degraded through various pathways, including hydrothermal degradation of nanoporous hosts and chemical degradation of amine guests via urea formation and oxidation. To inhibit such degradation pathways, it is extremely important to properly design the nanoporous structures of the hosts and the molecular structures of the amine guests. By combining macroporous silica hosts, poly(ethylenimine) (PEI) functionalized with various alkyl epoxides, and phosphate-based oxidative stabilizers, we could synthesize adsorbents exhibiting low energy demands for CO2 capture and unprecedentedly high thermochemical stability under TSA conditions. The macroporous silica host synthesized by assembling fumed silica particles via spray-drying exhibited high hydrothermal stability and enabled uniform distribution of bulky amine polymers within its pores. The functionalization of PEI with alkyl epoxides converted its primary amines into hindered secondary amines, leading to a significant reduction in energy demand for TSA cycles and a remarkable improvement in long-term stabilities. The oxidative stability of amines could be drastically improved by adding phosphate metal-binding reagents, which can poison ppm-level metal impurities that catalyze amine oxidation. The present discussions will provide important insights into designing practical adsorbents for CO2 capture from engineering perspectives.

Water-Soluble Squaramide-Functionalised Copolymers for Anion Recognition.

A series of ethylene glycol-based squaramide-containing copolymers were synthesised via a post-polymerisation functionalisation strategy. Conversion of polymeric amines to squaramides was found to proceed in good yields, representing a versatile method of incorporating squaramides into polymers for anion recognition. Analysis of the polymers by UV-Vis and fluorescence spectroscopy revealed that anion binding takes place similarly to that of small-molecule squaramides. The presence of a fluorescent sensing group on polymer-bound squaramides allowed for a fluorescent sensing mechanism for anions that followed a similar trend in selectivity in aqueous DMSO solution, with selectivity observed for H2 PO4 - , AcO- and SO4 2- over other common anions tested. The anion response and selectivity towards anions was similar to that of analogous small-molecule squaramides, however polymeric squaramides exhibited a greater resistance to deprotonation by more basic anions, which was attributed to the closer proximity of individual squaramides on a macromolecule. The squaramide containing polymers exhibited good water solubility, overcoming a common problem for anion sensors which are typically not sufficiently soluble in water to function in many required applications. Despite no anion binding being observed in water, this represents a simple and effective method of creating fully water-soluble anion receptors which may be adapted to give improved binding affinity and selectivity depending on the anion binding moiety. This article is protected by copyright. All rights reserved.

Design of Nanostraws in Amine-Functionalized MCM-41 for Improved Adsorption Capacity in Carbon Capture.

Polymeric amine encapsulation in high surface area MCM-41 particles for CO2 capture is well established but has the drawback of leaching out the water-soluble polymer upon exposure to aqueous environments. Alternatively, chemical (covalent) grafting amine functional groups from an alkoxysilane such as 3-aminopropyltriethoxysilane (APTES) on MCM-41 offer better stability against this drawback. However, the diffusional restriction exhibited by the narrow uniform MCM-41 pores (2-4 nm) may impede amine functionalization of the available silanol groups within the inner mesoporous core. This leads to incomplete amine functionalization and could reduce the CO2 adsorption capacity in such materials. Our concept to improve access to the MCM-41 interior is based on the incorporation of nanostraws with larger inner diameter (15-30 nm) to create a hierarchical porosity and enhance the molecular transport of APTES. Halloysite nanotubes (HNT) are used as tubular straws that are integrated into the MCM-41 matrix using an aerosol-assisted synthesis method. Characterization results show that the intrinsic structure of MCM-41 remains unaltered after the incorporation of the nanostraws and amine functionalization. At an optimal APTES loading of 0.5 g (X = 2.0), the amine-functionalized composite of MCM-41 with straws (APTES/M40H) has a 20% higher adsorption capacity than the amine-modified MCM-41 (APTES/MCM-41) adsorbent. Furthermore, the CO2 adsorption capacity APTES/M40H doubles that of APTES/MCM-41 when normalized based on the composition of MCM-41 in the composite particle with straws. The facile integration of nanostraws in MCM-41 leading to hierarchical porosities could be effective toward the mitigation of diffusional restriction in porous materials with potential for other catalytic and adsorption technologies.

Insights into the proton-enhanced mechanism of hexavalent chromium removal by amine polymers in strong acid wastewater: Reduction of hexavalent chromium and sequestration of trivalent chromium

Adsorption is a green technology of treating heavy metal-contaminated strong acid wastewaters for the recycling of heavy metal and reuse of strong acid. Herein, three amine polymers (APs) with different alkalinities and electron donating abilities were prepared to investigate the adsorption-reduction processes of Cr(VI). It was found that the removal of Cr(VI) was controlled by the concentration of –NRH+ on the surface of APs at pH > 2, which relies on the alkalinity of APs. However, the high concentration of NRH+ significantly facilitated the adsorption of Cr(VI) on the surface of APs and accelerated the mass transfer between Cr(VI) and APs at strong acid environment (pH ≤ 2). More importantly, the reduction of Cr(VI) was enhanced at pH ≤ 2, due to the high reduction potential of Cr(VI) (E ≥ 0.437). The ratio of reduction to adsorption (α) of Cr(VI) was above 0.70, and the proportion of Cr(III) bonding on Ph-AP excessed 67.6 %. Finally, a proton-enhanced mechanism of Cr(VI) removal was verified by analyzing FTIR and XPS spectra as well as constructing DFT model. This study provides a theoretical basis for the removal of Cr(VI) in the strong acid wastewater.

Quantifying amines in polymers by XPS

Quantifying amines in polymers by XPS

Surface modification of polyester films with polyfunctional amines: Effect on bacterial biofilm formation

The development of materials with antifouling properties is crucial in many areas, including medicine and food packaging. In this study, 2D-matrices made of polylactic acid (PLA), polyhydroxybutyrate (PHB), or polyhydroxybutyrate-co-valerate (PHB-HV) were surface functionalized through aminolysis with three polyfunctional amines, 1,6-hexamethylenediamine (HDA), tetraethylenepentamine (TEPA), and polyallylamine hydrochloride (PAH). The aminolysis procedure was thoroughly studied to ensure a high amount of amine groups while preserving the structural properties of the films. Interestingly, PHB and PHB-HV were found to be more sensitive to aminolysis than PLA, and the highest amino group density was achieved in surfaces etched with PAH. A decrease in the contact angle from ca. 85° to ca. 70° was revealed for polymers functionalized with HDA and TEPA and a drastic reduction in Staphylococcus epidermidis adhesion was observed for PHB-HV functionalized with the polymeric amine PAH. Polymer antimicrobial activity was found to be related to the degree of surface functionalization. The functionalized, cationic polymer surfaces were supposed to act upon contact with bacteria, without releasing any antimicrobial agent. The developed bioactive surfaces may have potential applications as flexible films for food packaging.

A Flexible and Polymer‐Based Chemiresistive CO2 Gas Sensor at Room Temperature

AbstractCO2 sensing is important in many applications ranging from air‐quality monitoring to food packaging. In this study, an amine‐functionalized copolymer, poly(N‐[3‐(dimethylamino)propyl]‐methacrylamide‐co‐2‐N‐morpholinoethyl methacrylate) (p(D‐co‐M)) is synthesized, offering moderate basicity suitable for a wide CO2 detection range. Taking advantage of this characteristic of p(D‐co‐M), this polymer is used for designing a chemiresistive, low‐cost, flexible, and reversible CO2 sensor. The p(D‐co‐M)‐based sensors show a noticeable decrease in their direct current resistance and alternating current impedance upon exposure to a wide range of CO2 concentration (1–100%) at room temperature with a response and a recovery time of 6 and 14 min, respectively. Additionally, the p(D‐co‐M)‐based sensors demonstrate a favorable selectivity to CO2 in the presence of interfering gases including methanol, ethanol, toluene, and acetone. Surface potential measurements show an increase of +6.34 V upon exposure to humidity and CO2, indicating the protonation of the polymer's amine sites, facilitating the detection of CO2 in the wet environment. This sensor is efficient for detecting CO2 concentration released during fermentation of kimchi as a food model.