Polymer Functional Groups Research Articles

Soft Ionics: Governing Physics and State of Technologies

Soft ionic materials combine charged mobile species and tailored polymer structures in a manner that enables a wide array of functional devices. Traditional metal and silicon electronics are limited to two charge carriers: electrons and holes. Ionic devices hold the promise of using the wide range of chemical and molecular properties of mobile ions and polymer functional groups to enable flexible conductors, chemically specific sensors, bio-compatible interfaces, and deformable digital or analog signal processors. Stand alone ionic devices would need to have five key capabilities: signal transmission, energy conversion/harvesting, sensing, actuation, and signal processing. With the great promise of ionically-conducting materials and ionic devices, there are several fields working independently on pieces of the puzzle. These fields range from waste-water treatment research to soft robotics and bio-interface research. In this review, we first present the underlying physical principles that govern the behavior of soft ionic materials and devices. We then discuss the progress that has been made on each of the potential device components, bringing together findings from a range of research fields, and conclude with discussion of opportunities for future research.

Excess polymer-assisted crystal growth method for high-performance perovskite photodetectors

Defects in grain boundaries and at the surface of perovskite polycrystalline film lead to nonradiative recombination losses and ion migration, which seriously affects the performance and stability of optoelectronic devices. However, the process of passivation by using functional groups in polymers is expected to solve the problem. In this work, a tandem-like perovskite photodetector (PD) is developed, and an improved solution process is proposed to promote perovskite crystal growth and reduce the horizontal grain boundaries by using excess poly(methyl methacrylate) (PMMA) as anti-solvent. In addition, PMMA retained in perovskite grains acts as an interlayer for storing photocarriers, reducing the dark current and enhancing the PD gain. As a result, optimal perovskite PD exhibits a peak specific detectivity of 3.38 × 1012 Jones, a high responsivity of 5.65 A/W, a linear dynamic range of 80 dB, and an external quantum efficiency of 1321% under 532 nm illumination at the small bias of − 1 V. In addition, the PD has a fast response (5.90 μs rise time, 6.75 μs decay time). These results combine to provide a low-cost method for designing high-performance, ultrafast-response perovskite optoelectronic devices with low power consumption.

Characteristics and Biological Activity of Exopolysaccharide Produced by Lysobacter sp. MMG2 Isolated from the Roots of Tagetes patula.

In the present study, exopolysaccharide (EPS) produced by Lysobacter sp. MMG2 (lyEPS) was characterized and purified. The lyEPS-producing strain Lysobacter sp. MMG2 was isolated from the roots of Tagetes patula. When lyEPS was produced in tryptic soy broth with 1% glucose and the lyophilized powder was measured, the yield was found to be 0.67 g/L. The molecular weight (Mw) of lyEPS was 1.01 × 105 Da. Its monosaccharide composition includes 84.24% mannose, 9.73% glucose, 2.55% galactose, 2.77% arabinose, 0.32% xylose, and 0.03% rhamnose. Scanning electron microscopy (SEM) revealed that lyEPS has various round and rough surfaces. Fourier-transform infrared (FTIR) analysis identified its carbohydrate polymer functional groups. Moreover, thermogravimetric analysis of lyEPS revealed two events of mass loss: the first was water loss, which resulted in 3.97% mass loss and the second event occurred at approximately 212 °C. lyEPS could inhibit biofilm-producing pathogenic bacteria without any antimicrobial activity. Furthermore, lyEPS at a concentration of 4 mg/mL could exhibit potent 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging activity (89.25%). These results indicate that lyEPS could be a promising candidate for industrial development if its biological activity is further explored.

Assessment of Physicochemical and In Vivo Biological Properties of Polymeric Nanocapsules Based on Chitosan and Poly(N-vinyl pyrrolidone-alt-itaconic anhydride).

Drug delivery is an important field of nanomedicine, and its aim is to deliver specific active substances to a precise site of action in order to produce a desired pharmacological effect. In the present study nanocapsules were obtained by a process of interfacial condensation between chitosan (dissolved in the aqueous phase) and poly(N-vinyl pyrrolidone-alt-itaconic anhydride), a highly reactive copolymer capable of easily opening the anhydride ring under the action of amine groups of chitosan. The formed amide bonds led to the formation of a hydrogel membrane. The morphology of the obtained nanocapsules, their behavior in aqueous solution of physiological pH, and their ability to encapsulate and release a model drug can be modulated by the parameters of the synthesis process, such as the molar ratio between functional groups of polymers and the ratio of the phases in which the polymers are solubilized. Although a priori both polymers are biocompatible, this paper reports the results of a very detailed in vivo study conducted on experimental animals which have received the obtained nanocapsules by three administration routes—intraperitoneal, subcutaneous, and oral. The organs taken from the animals’ kidney, liver, spleen, and lung and analyzed histologically demonstrated the ability of nanocapsules to stimulate the monocytic macrophage system without producing inflammatory changes. Moreover, their in vivo behavior has been shown to depend not only on the route of administration but also on the interaction with the cells of the organs with which they come into contact. The results clearly argue the biocompatibility of nanocapsules and hence the possibility of their safe use in biomedical applications.

A Polyimide-Based Photocatalyst for Continuous Hydrogen Peroxide Production Using Air and Water under Solar Light

A Polyimide-Based Photocatalyst for Continuous Hydrogen Peroxide Production Using Air and Water under Solar Light

Hierarchically palladium nanoparticles embedded polyethyleneimine–reduced graphene oxide aerogel (RGA–PEI–Pd) porous electrodes for electrochemical detection of bisphenol a and H2O2

• 3-dimensional reduced graphene oxide aerogel (RGA) composite has possessed numerous active sites. • Functional groups of polymer is tethered to the RGA through C–N bonds with graphene. • Amine groups play a crucial role in detection of bisphenolA. • Properties of electrocatalyst was demonstrated for both the environmental and biological samples. Three-dimensional (3D) hierarchically porous nanoelectrodes consisted of palladium nanoparticles embedded in polyethlyenimine (PEI)-reduced graphene oxide aerogel (RGA) was meticulously engineered to detect bisphenol A (BPA) and hydrogen peroxide (H 2 O 2 ). Abundant positive charges of PEI enable the formation of 3D porous structures by tethering to the RGA through C–N bonds with functional groups on the graphene whereas the amine groups in the PEI allow anchoring the Pd NPs which ensure their uniform dispersion across the surface of the aerogel, while preserving its 3D porous structure. In conclusion, it is considered that Pd 0 and Pd 2+ contribute to catalytic performance through redox reaction with each other to Pd 2+ and Pd 4+ states. This unique structure provides highly electrocatalytically active sites to oxidize BPA and reduce H 2 O 2 . Under optimal conditions, an RGA-PEI-Pd modified electrode exhibited low detection limits of 25.5 nM for BPA and 16.2 nM for H 2 O 2 . Various analytical techniques including electrochemical spectroscopy were systematically performed to understand the cause of their unique electrocatalytic properties. Finally, the developed electrochemical electrodes were applied to real environmental and biological samples (i.e., BPA contained water samples from rivers and lakes and MCF-7 cells contained clinical samples) and showed excellent reusability ( e.g. , recovery rate of 96 to 104.3%).

Adsorption of neutral and negatively charged low-molecular-weight carbonyls in reverse osmosis permeates by ion-exchange resins

Reverse osmosis (RO) has been increasing widely used in water and wastewater treatment to provide high-quality water, such as in industrial pure water production and municipal (non)potable water reuse. However, some low-molecular-weight (LMW) compounds, such as LMW carbonyls, penetrate through RO membranes and are present in the RO permeate, resulting in potential risk to human health or industrial production. Ion-exchange (IX) resins are widely used to help eliminate residual LWM organic compounds from RO permeates, but their elimination performance for carbonyls is not well understood. In this study, seven commercially available resins were employed to explore the adsorption performance for the elimination of representative carbonyls in RO permeate. In general, the adsorption performance of selected resins with regular polymer composition, pore structure and functional group was poor for LMW neutral carbonyl compounds, but efficient for carboxylic acids (number of carbon atoms is less than 4). Among target carboxylic acids, the gel-N+(CH3)3 resin exhibited rapid adsorption kinetics, performing better in the removal of LMW carboxylic acids with shorter alkyl chains and more carboxyl groups. In particular, binary carboxylic acids were adsorbed 3–5 times faster on resins compared with their monoacid counterparts. Charge density was the dominant factor affecting the adsorption performance of carbonyl compounds, followed by hydrophobicity, molecular chain length, and the presence of H attached to the carbonyl C. This study implies that neutral carbonyls cannot be efficiently eliminated by IX resin, and green oxidation processes, such as vacuum UV oxidation, are suggested for the conversion of such compounds to readily removable negatively charged carboxylic acids.

Gamma Irradiation of Cellulose Acetate-Polyethylene Glycol 400 Composite Membrane and Its Performance Test for Gas Separation

Gas separation processes through membrane permeation have attracted the attention of researchers recently due to their promising applications. In this study, we modified the cellulose acetate (CA) membrane to improve the membrane performance of CO2/CH4 gas separation. The CA membrane was modified by adding polyethylene glycol (PEG) 400 as the carrier and N, N’-methylenebisacrylamide (MBA) as the cross-linking agent. Gamma-ray from cobalt 60 was used as a reaction initiator with variation in irradiation doses. The membrane characterization tests were conducted using scanning electron micrograph (SEM), Fourier transforms infrared (FTIR), and instron tensile strength tester. The permeability and selectivity of the membranes were tested against the single gases CO2 and CH4. The SEM analysis showed the morphology change in the membrane surface by gamma irradiation and a crosslinking agent. The spectra of FTIR showed a change in peak intensity on several polymer functional groups in the presence of gamma-ray irradiation. The tensile strength test showed that membranes with MBA have a higher mechanical strength than those without MBA. Based on the membrane permeability and selectivity tests, CO2 gas permeability was affected by pressure. The ideal selectivity of CO2/CH4 shows that the irradiated membrane has a higher selectivity than that of the non-irradiated membrane.

Manufacturing and photocrosslinking of a new bio‐based dimethacrylate resulting in hydrophobic crosslinked films

AbstractA new bio‐based dimethacrylate (EMHO) consisting of three isomers, that is (ethane‐1,2‐diyl‐bis(9‐methacryloyloxy‐10‐hydroxy octadecanoate) [EMHO‐i1], ethane‐1,2‐diyl‐9‐hydroxy‐10‐methacryloyloxy‐9′‐methacryloyloxy‐10′‐hydroxy octadecanoate [EMHO‐i2], and ethane‐1,2‐diyl‐bis(9‐hydroxy‐10‐methacryloyloxy octadecanoate [EMHO‐i3]), was made by a three‐step reaction starting from esterification of oleic acid with ethylene glycol followed by epoxidation in a second step, and epoxy ring‐opening reaction with methacrylic acid in a third step. The new dimethacrylate obtained was photocured applying ultra‐violet technology to receive a neat polymer on the one hand and in the presence of a further methacrylate, such as 4‐(4‐methacryloyloxyphenyl)‐butan‐2‐one (MAPO) or methyl 9‐(1H‐imidazol‐1‐yl)‐10‐(methacryloyloxy)‐octadecanoate and methyl 9‐(methacryloyloxy)‐10‐(1H‐imidazol‐1‐yl)‐octadecenoate available as isomer mixture (MIMAO), on the other hand. The photopolymerization kinetic study applying photo‐differential scanning calorimetry technology showed that the addition of MAPO or MIMAO during photocuring resulted in an increase in both polymerization rate and final conversion on monomer in comparison with the homopolymerization of EMHO. As expected, the network density obtained by the study of the elastic modulus of the copolymers was reduced compared to the homopolymer caused by the presence of the methacrylate MAPO or MIMAO comprising only one polymerizable functional group. The crosslinked polymer films contain high gel content. Those films made by using an excess of MAPO showed a glass transition above room temperature caused by the aromatic ring comprising in MAPO. High contact angle values for water indicate the high hydrophobicity of the crosslinked polymer films that is attributed to the long alkyl chains contained in the bio‐based dimethacrylate. The copolymer made from the bio‐based dimethacrylate with MAPO excess may be interesting for application as a water‐repellent coating for surface protection and protection against corrosion.

N,N-Bis(hexyl α-d-acetylmannosyl) Acrylamide

Glycosyl monomers for the assembly of multivalent ligands are typically synthesized using carbohydrates with biological functions and polymerizable functional groups such as acrylamide or styrene introduced into the carbohydrate aglycon, and monomers polymerized using a radical initiator. Herein, we report the acryloylation of 6-aminohexyl α-d-mannoside and its conversion into the glycosyl monomer bearing an acrylamide group. The general acryloylation procedure afforded the desired N-hexyl α-d-acetylmannosyl acrylamide monomer as well as an unexpected compound with a close Rf value. The compounds were separated and analyzed by nuclear magnetic resonance spectroscopy and mass spectrometry, which revealed the unknown compound to be the bivalent N,N-bis(hexyl α-d-acetylmannosyl) acrylamide monomer, which contains two hexyl mannose units and one acrylamide group. To the best of our knowledge, this side reaction has not previously been disclosed, and may be useful for the construction of multivalent sugar ligands.

Role of the Anilinium Ion on the Selective Polymerization of Anilinium 2-Acrylamide-2-methyl-1-propanesulfonate

The development of anilinium 2-acrylamide-2-methyl-1-propanesulfonate (Ani-AMPS) monomer, confirmed by 1H NMR, 13C NMR, and FTIR, is systematically studied. Ani-AMPS contains two polymerizable functional groups, so it was submitted to selective polymerization either by free-radical or oxidative polymerization. Therefore, poly(anilinium 2-acrylamide-2-methyl-1-propanesulfonic) [Poly(Ani-AMPS)] and polyaniline doped with 2-acrylamide-2-methyl-1-propanesulfonic acid [PAni-AMPS] can be obtained. First, the acrylamide polymer, poly(Ani-AMPS), favored the π-stacking of the anilinium group produced by the inter- and intra-molecular interactions and was studied utilizing 1H NMR, 13C NMR, FTIR, and UV-Vis-NIR. Furthermore, poly(Ani-AMPS) fluorescence shows quenching in the presence of Fe2+ and Fe3+ in the emission spectrum at 347 nm. In contrast, the typical behavior of polyaniline is observed in the cyclic voltammetry analysis for PAni-AMPS. The optical properties also show a significant change at pH 4.4. The PAni-AMPS structure was corroborated through FTIR, while the thermal properties and morphology were analyzed utilizing TGA, DSC (except PAni-AMPS), and FESEM.

Fabrication and Characterization of Silk Fibroin-Based Nanofibrous Scaffolds Supplemented with Gelatin for Corneal Tissue Engineering

Tissue engineering is a promising approach to overcome the severe worldwide shortage of healthy donor corneas. In this work, we have developed a silk-gelatin composite scaffold using electrospinning and permeation techniques to achieve the properties comparable to cornea analog. In particular, we present the fabrication and comparative evaluation of the novel gelatin sheets consisting of silk fibroin nanofibers, which are prepared using silk fibroin (SF) (in formic acid) and SF (in aqueous) electrospun scaffolds, for its suitability as corneal stromal analogs. All the fabricated samples were treated with ethanol vapor (T) to physically crosslink the silk nanofibers. Micro/nano-scale features of the fabricated scaffolds were analyzed using scanning electron microscopy micrographs. Fourier transform infrared spectroscopy revealed characteristic peaks of polymeric functional groups and modifications upon ethanol vapor treatment. Transparency of the scaffolds was determined using UV-visible spectra. Among all the fabricated samples, the gelatin-permeated SF (in formic acid; T) scaffold showed the highest level of transparency, i.e., 77.75 ± 2.3%, which is similar to that of the native cornea (∼70%–90% [variable with age group]) with healthy acute vision. Contact angle of the samples was studied to estimate the hydrophilicity of the scaffolds. All the scaffolds except non-treated SF (in aqueous; NT) were found to be significantly stable up to 14 days when incubated in phosphate buffered saline at 37°C. Treated samples showed significantly better stability, both physically and microscopically, in comparison to nontreated samples. Proliferation and viability assays of rabbit corneal fibroblast cells (SIRC) and mouse fibroblast cells (L929 RFP) when cultured on fabricated scaffolds revealed remarkable cellular compatibility with gelatin-permeated SF (in formic acid; T) scaffolds compared to SF (in aqueous; T). Unlike other reports in the existing literature, this work presents the design and development of a nanofibrous silk-gelatin composite that exhibits acceptable transparency, cellular biocompatibility, as well as improved mechanical stability comparable to that of native cornea. Therefore, we anticipate that the fabricated novel scaffold is likely to be a good candidate for corneal tissue construct. Moreover, among the fabricated scaffolds, the outcomes depict gelatin-permeated SF (in formic acid; T) composite scaffold to be a better candidate as a corneal stromal analog that carries properties of both the silk and gelatin, i.e., optimal transparency, better stability, and enhanced cytocompatibility.

On the development of electrochemical sensors coated with polycaprolactone

The main aim of this study was to test the biopolymer polycaprolactone (PCL) as an electrode modifier for the electrochemical detection of dopamine (DA). PCL was chosen following a search for polymers with the appropriate geometry and functional groups for dopamine detection. The chemical structure and the average molecular weight of the synthesized PCL were determined by 1H NMR, while DSC measurements showed a decrease in the crystallinity of a star-shaped polymer compared to a linear polymer. Atomic force microscopy and wettability tests performed on PCL-coated ITO electrodes demonstrated the influence of polymer architecture and functional groups on hydrophilicity and film morphology. Electrochemical studies revealed that electrodes coated with star polymers ending with carboxyl groups show good activity and selectivity, thus demonstrating the effectiveness and applicability of the developed sensors for the electrochemical detection of DA.

Evaluation of microplastics ingested by sea cucumber Stichopus horrens in Pulau Pangkor, Perak, Malaysia.

The widespread presence of microplastics has caused significant concerns on their potential effects on marine ecosystems. Microplastics are classified as plastic products of less than 5 mm in size and are known to be one of the most dangerous aquatic debris to marine species. Sea cucumbers are deposit feeders living in sediment regions and benthic zone that may collect microplastics in low-energy environments. This research aims to evaluate the types of microplastic isolated from the intestine of Stichopus horrens in Malaysia. This species is selected because it is mainly found in this island. Pulau Pangkor is one of the leading tourism destinations on the small islands is facing increasing numbers of tourists and development and it is useful for sustainable study. A total of 20 S. horrens samples collected from Pulau Pangkor, Malaysia were dissected, and their intestines were collected for digestion. Microplastics were extracted using NaOH and filtered using filter paper. Microplastic identification was conducted on the based of the physical characteristics (colour, shape, size) and chemical characterisation was evaluated using FTIR for polymer functional groups. A total of 1446 unit of microplastics were found in S. horrens. Among various types and colours, fibre (90%) and black (59%) were dominant amongst the various particles identified. The majority of microplastics sizes were 0.51 μm and 1-2 μm. Two polymer materials were identified, namely polyethylene and poly(methyl methacrylate). As a conclusion, the findings of the study will serve as primary data for pollution indicators in respective islands. The microplastics could impact the immune system and upset gut's balance of human.

Ion-Exchange Technology for Lactic Acid Recovery in Downstream Processing: Equilibrium and Kinetic Parameters

The downstream processing for the separation and purification of lactic acid is a hot research area in the bio-refinery field due to its continuous growing market in different sectors, such as the food, cosmetic and pharmaceutical sectors. In this work, the use of ion-exchange technology for lactic acid recovery is proposed. For that, four anion exchange resins with different polymer structures and functional groups were tested (A100, MN100, A200E and MP64). The sorption process was optimized by the Box–Behnken factorial design, and the experimental data obtained in the sorption process were analyzed by using the response surface methodology and fitted at different isotherms and kinetics models. Moreover, regenerant type, contact time and solid/liquid ratio were evaluated in the desorption process. Results showed that the best resin for lactic acid removal was A100, at pH = 4, with a resin/lactic acid solution ratio of 0.15 g/mL during a maximum of 1 h, achieving 85% of lactic acid removal. Moreover, equilibrium data sorption of lactic acid onto A100 resin was fitted by a Langmuir isotherm and by a kinetic model of a pseudo-second order. In addition, in the desorption process, it was stablished that a resin/regenerant ratio of 0.15 g/mL during 30 min with 0.1 M of NaOH solution provided the best results (4.45 ± 0.08 mg/g).

Development of effectively costed and performant novel cation exchange ceramic nanocomposite membrane based sulfonated PVA for direct borohydride fuel cells

A direct borohydride fuel cell (DBFC) is a type of low temperature fuel cell, and to commercialize this type of fuel cell, it requires efficient and inexpensive proton exchange membranes. In this study, a binary polymer blend is formulated from inexpensive and ecofriendly polymers such as iota carrageenan (IC) and polyvinyl alcohol (PVA). Zirconiam phosphate (ZrPO4) was synthesized from a simple impregnation — calcination method and later embedded as a doping agent into the polymeric matrix with percentage (1–7.5) wt.%. The novel nanocomposite membranes were evaluated by TGA, DSC, FTIR, XRD and SEM. The oxidative stability and tensile strength of the obtained membranes were enhanced and achieved results better than those of Nafion117 due to an increase in the number of hydrogen bonds formed between the polymer functional groups and oxygen functional groups of ZrPO4with increasing doping concentration. In addition, the borohydride permeability of the membranes decreased with increasing ZrPO4weight percentage, while the ionic conductivity and power density increased to 25.5 mS cm−1 and 66 mW cm−2, respectively, for membrane with 5 wt.% of ZrPO4. The fabricated membrane with the optimum properties (PVA/IC/ZrPO4− 5) can be efficient as a proton exchange membrane towards the development of green and low cost DBFCs.

Systematic Modification of the Glass Transition Temperature of Ion-Pair Comonomer Based Polyelectrolytes and Ionomers by Copolymerization with a Chemically Similar Cationic Monomer.

Ion-pair comonomers (IPCs) where both the anion and cation contain polymerizable functional groups offer a route to prepare polyampholyte, ion-containing polymers. Polymerizing vinyl functional groups by free-radical polymerization produces bridging ion-pairs that act as non-covalent crosslinks between backbone segments. In particular the homopolymerization of the IPC vinyl benzyl tri-n-octylphosphonium styrene sulfonate produces a stiff, glassy polymer with a glass transition temperature (Tg) of 191 °C, while copolymerization with a non-ionic acrylate produces microphase separates ionomers with ion-rich and ion-poor domains. This work investigates the tuning of the Tg of the polyelectrolyte or ion-rich domains of the ionomers by copolymerizing with vinyl benzyl tri-n-octylphosphonium p-toluene sulfonic acid. This chemically similar repeat unit with pendant rather than bridging ion-pairs lowers the Tg compared to the polyelectrolyte or ionomer containing only the IPC segments. Rheological measurements were used to characterize the thermomechanical behavior and Tg of different copolymers. The Tg variation in the polyelectrolyte vs. weight fraction IPC could be fit with either the Gordon–Taylor or Couchman–Karasz equation. Copolymerization of IPC with a chemically similar cationic monomer offers a viable route to systematically vary the Tg of the resulting polymers useful for tailoring the material properties in applications such as elastomers or shape memory polymers.

Sorption of Heavy Metal Ions by Composite Materials Based on Polycarboxylic Acids and Bentonite Clay

The paper shows the study results of sorption capacities of composite gels based on polyacrylic and polymethacrylic acids with bentonite clay as the mineral filler concerning heavy metal ions (Pb+2, Cu+2, Ni+2, Zn+2, Fe+2, Cd+2). The binding of metal ions to gels occurs through the formation of electrostatic bonds between the charged surface of bentonite clay and ionogenic functional groups of polymers in the composition, as well as the coordination bonds between metal ions and unshared pairs of oxygen electrons in the functional groups of polymers. The gel swelling degree decreases in metal solutions with increasing metals concentration and the content of BC in the composite. The sorption and desorption of heavy metal ions from the polymer-clay composites from model solutions and samples of industrial wastewater from the Kazakhstani metallurgical plants were evaluated. The adjustment of the pH, the temperature of the medium and the clay content in the composite leads to increasing the degree of sorption and achieving regeneration of the used composite gels in certain media. The data obtained testify to the prospects of using these composites as effective sorbents of heavy metals from industrial wastewaters expanding the range of composite materials for wastewater treatment.

2D Correlation Spectroscopy (2DCoS) Analysis of Temperature-Dependent FTIR-ATR Spectra in Branched Polyethyleneimine/TEMPO-Oxidized Cellulose Nano-Fiber Xerogels.

Fourier transform infrared spectroscopy in attenuated total reflectance geometry (FTIR-ATR), combined with a 2D correlation analysis, was here employed to investigate temperature-induced spectral changes occurring in a particular type of novel cellulosic-based nano-material prepared using 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) oxidized and ultra-sonicated cellulose nano-fibers (TOUS-CNFs) as three-dimensional scaffolds, and branched polyethyleneimine (bPEI) as cross-linking agent. The aim was to highlight the complex sequential events involving the different functional groups of the polymeric network, as well as to gain insight into the interplay between the amount of bPEI and the resulting sponge-like material, upon increasing temperature. In this framework, synchronous and asynchronous 2D spectra were computed and analyzed in three wavenumber regions (900–1200 cm−1, 1500–1700 cm−1 and 2680–3780 cm−1), where specific vibrational modes of the cellulosic structure fall, and over a T-range between 250 K and 340 K. A step-by-step evolution of the different arrangements of the polymer functional groups was proposed, with particular regard to how the cooperativity degree of inter- and intramolecular hydrogen bonds (HBs) changes upon heating. Information acquired can be useful, in principle, in order to develop a next-generation, T-sensitive novel material to be used for water remediation applications or for drug-delivery nano-vectors.

Insights into the effect of polymer functionalization of multiwalled carbon nanotubes in the design of flexible strain sensor

In the background of designing a polymer nanocomposite based flexible strain sensors, homogenized dispersion of nanofillers remain challenging due to the trade-off between upholding of inherent characteristics of nanofillers and stable dispersion of nanofillers in the polymer matrix. This study provides an approach of balancing the stable dispersion of nanofillers and maintain the inherent characteristics of nanofibers by the method of polymer functionalization. Herein, two oppositely charged polymers polystyrene sulfonate sodium salt (PSS) and poly-diallyl-dimethyl-ammonium chloride (PDDA) are used separately to functionalize the multiwalled carbon nanotubes (CNT) and it dispersed in poly (vinylidene difluoride) (PVDF) polymer matrix to get flexible nanocomposite strain sensor to investigate both electrical conductivity and the gauge factor. PSS functionalized CNT (PSS-CNT) shows better dispersion than the PDDA-CNT in PVDF matrix. Besides, the electrical conductivity of PVDF/PSS-CNT (0.44 ± 0.02 Scm−1) is about 28 times higher than the PVDF/PDDA-CNT, and the gauge factor of PVDF/PSS-CNT (9.8 ± 0.3) is 2-fold higher than the PVDF/PDDA-CNT. The stable dispersion of PSS-CNT is due to the repulsive nature existing between the individual CNTs caused by the attachment of charged polymer functional groups as same as intrinsic functional groups of the pristine CNT. This work signifies the role of synergy between the charged particles in the functional groups and charged nature of the filler influencing the performance of flexible strain sensors. The detailed investigation using various techniques reveals significance of selection of suitable polymers for functionalization by showing its influence in the context of designing the high-performance flexible strain sensor.