Absorption Of Polymers Research Articles

물 흡수에 따른 다양한 고분자 재료의 기계적/트라이볼로지적 물성 연구

The physical, chemical and mechanical properties of polymer materials used in water environment for a long time will change due to their water absorption characteristics, which will affect their tribological properties. This work studied the changes of physicochemical, mechanical, and tribological properties for five kinds of polymer materials (polyethylene, polyformaldehyde,polyamide, polytetrafluoroethylene, and poly-ether-etherketone) before and after water absorption. The mechanism of water absorption for polymer materials was revealed by molecular dynamics simulation. The results show that the higher the water absorption of polymer, the larger the swelling volume, the more the surface hardness and compressive strength decrease, and the toughness and friction coefficient of the material increase obviously. The water absorption status of polymer materials is closely related to the polarity of molecular chain. Water molecules are easy to form hydrogen bonds with polymer molecular chains of high polarity, which is the main factor of water absorption.

Metastable Polymer Adsorption Dictates the Dynamical Gradients at Interfaces

Polymer adsorption proceeds through a wide variety of metastable states due to kinetic constraints originating from the pinning of segments on solid interfaces, creating an interfacial adsorption layer composed of flattened trains, loosely adsorbed loops, and tails of chains. In this work, we show that the metastable structures of adsorption layers developed via thermal annealing at a temperature above glass-transition temperature Tg determine the length scale of interfacial mobility gradient dynamics (ξdyn). Specifically, we find that 1) the evolution of ξdyn mimics the trend in the slow kinetics of polymer absorption and 2) ξdyn grows linearly with the thickness of the overall interfacial adsorption layer. The findings reinforce the idea that the interfacial dynamical gradients are relevant to polymer adsorption and also imply that extension of the loosely adsorbed chains into the film interior could facilitate the propagation of suppressed dynamics originating at the interface.

Optical characteristics and bacterial-resistance ability of PVA/ZnO nanocomposites

Poly(vinyl alcohol) (PVA) thin films with different amounts of zinc oxide (ZnO) nanoparticles (NPs) (0.001, 0.002, 0.003, 0.004 and 0.005 ​g) were prepared using the casting method. The structural characteristics of the PVA polymer, ZnONPs and the mixture of polymer and ZnO NPs with a particle size of 80 ​nm have been studied using X-ray diffraction, Scanning Electron Microscopy and Fourier Transform Infrared spectroscopy. The optical characteristics of PVA/ZnO nanocomposites were studied in the wavelength range of 200–700 ​nm. According to experimental research, adding more ZnONPs to nanocomposites improves the PVA polymer's absorbance, absorption coefficient, extinction coefficient, refractive index and real and imaginary dielectric constants. As the amount of ZnONPs increases, the transmittance and energy gap of the PVA polymer decrease. Research on the antibacterial activity of these nanocomposites was conducted using Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella quasipneumoniae subsp. Similipneumoniae as pathogen microorganisms. According to the findings, the antibacterial activity of NPs is greatly influenced by their chemical make-up and form. Moreover, increasing the amount of ZnO in the composites causes an increase in antibacterial activity.

Impact of ZnS/Mn on the Structure, Optical, and Electric Properties of PVC Polymer.

The most efficient way to create novel materials that may be used in a variety of optoelectronic applications is thought to be doped mixed polymers with appropriate fillers. Undoped and doped PVC polymers with ZnS/Mn formed at different temperatures were fabricated using the casting method. The Rietveld method was used to discover the structure and microstructure of Zn0.95Mn0.05S prepared at T = 300, 400, and 500 °C. The distribution and existence of the nanofiller over the PVC matrix were determined via XRD, FTIR, EDS, and SEM techniques. The effect of the preparation temperatures of the ZnS/Mn nanofiller on the absorption, transmittance, reflectance, refractive index, extinction coefficient, dielectric constant, AC conductivity, electrical modulus, and DC conductivity activation energy data of the PVC polymer was studied using the diffused reflectance technique. Doping PVC with ZnS/Mn (prepared at 300 °C) lowered the direct and indirect optical band gaps from 5.4 and 4.52 eV to minimum values of 4.55 and 3.63 eV. The fluorescence intensity of pure PVC is greatly enhanced upon loading with ZnS/Mn. The PVC exhibited two near UV peaks, one violet and one blue color, while, in addition, the doped polymers exhibited green and orange colors. The corresponding CIE diagram for all the samples was also determined.

Mechanistic Insight of Polymer Effects on the Kinetic of Solution-Mediated Phase Transformation of Nitrofurantoin Anhydrate to Monohydrate.

Nitrofurantoin is an effective antibacterial drug for the treatment of lower urinary tract infection. However, the anhydrate form can easily transform to the less soluble hydrate form (monohydrate) during dissolution, resulting in a reduction of dissolution rate and oral bioavailability. Therefore, inhibition of phase transformation is vital to stabilize the quality of drugs. In this work, the potential of polyethylene glycol (PEG 8000), polyvinyl pyrrolidone (PVP K30), poloxamer 188 and hydroxypropyl methylcellulose (HPMC) to inhibit the hydration of nitrofurantoin during dissolution was investigated by experimental and simulation approaches. The rates of phase transformation were decreased in the presence of PEG 8000 and poloxamer 188, and PVP K30 and HPMC completely inhibited the phase transformation of anhydrate. The abundant hydrogen bond donor and acceptor groups of PVP and HPMC may easily establish intermolecular interactions with nitrofurantoin molecules, accounting for stronger inhibition of nucleation. Besides, the molecular dynamic simulation further indicated the formation of more extensive interactions between PVP K30 (or HPMC) and the (111) face of monohydrate, suggesting that the strong absorption of polymers on the surface and thus block the sites for incorporation of new growth. This study provides a mechanistic insight into the inhibition of nitrofurantoin hydration by polymeric additives, which helps design formulations and improve the physical stability of anhydrate.

D-A non-equivalent random strategy to achieve donor polymers for stable organic solar cells with efficiency over 17%

High efficiency organic solar cells with great stability are crucial for future commercialization. Herein, a simple electron-donating monomer 2,6-dibromo-4,8-bis(octyloxy)benzo[1,2-b:4,5-b'] dithiophene (BDT-O) was synthesized as the third component to be introduced into the D-A backbone of PM6 by D-A non-equivalent random copolymerization. A series of wide-bandgap D-A-D-D1-type random terpolymer donors PM6-Ox (x = 5, 10, 30) were obtained, in which BDT-O served as the third component D1, fluorinated bis-2-ethylhexyl thiophene substituted benzodithiophene served as the D component and the typical 1,3-bis(4-(2-ethylhexyl) thiophen-2-yl)-5,7-bis(2-alkyl) benzo[1,2-c:4,5-c']dithiophene-4,8-dione was used as the A component. Morphological and photoelectronic characterizations are investigated to reveal the effects of BDT-O unit on the photovoltaic (PV) performances of polymers. Small content of BDT-O unit introduced into PM6 can effectively tune the absorption, energy levels and molecular arrangement of polymers for better solar light-harvesting and enhanced charge transport. By fabricating organic solar cells (OSCs) with the common acceptor Y6, the PM6-O5:Y6-based device achieved a much higher PCE of 17.65% than that of the reference PM6:Y6-based device. Besides, PM6-O5:Y6-based devices exhibit high thermal- and storage-stability, as well as outstanding photo-stability. This work will provide valuable clues on the molecular design of high-efficiency polymer donors via D-A non-equivalent random copolymerization strategy by incorporating a simple D1 component.

Microstructure refinement and shrinkage mitigation of alkali-activated slag paste by superabsorbent polymer

This paper investigates the effects of superabsorbent polymer (SAP) dosage, particle size, addition method, and absorption status on the properties and microstructure of alkali-activated slag (AAS) pastes. The results show that incorporating SAP can mitigate the autogenous shrinkage and short-term drying shrinkage of the AAS pastes, mainly depending on the SAP dosage and size. The release of activator can promote the geopolymerisation around the SAP particles, which improves the local micro-hardness of the pastes and reduces the amount of capillary pores. This consequently densifies the microstructure around the SAP particles and mitigates the shrinkage of the AAS pastes. The large SAP particles are found to release activator to a farther distance than the small ones, which is more effective in mitigating the autogenous shrinkage. The promoted conversion from mesopores to gel pores in the paste with large SAP is also beneficial to reducing the driving force of autogenous shrinkage. By contrast, the addition method and absorption status of SAP particles have marginal impacts on the autogenous shrinkage as the released activators travel a similar distance within the AAS pastes. Moreover, adding SAP particles increases the number of gel pores and macropores regardless of their size or absorption status, leading to an increased long-term drying shrinkage and a weakened mechanical property of the AAS paste. Overall, the findings of this study can guide the mix design and preparation of AAS materials with SAP.

A new heteroleptic cuprous polymer constructed by a cyanopyridine ligand exhibiting a supramolecular framework structure and luminescence.

Luminescent cuprous complexes are of great importance among coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The title heteroleptic cuprous polymer solvate, catena-poly[[[(9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane)-κ2P,P'](μ-pyridine-3-carbonitrile-κ2N1:N3)copper(I)] hexafluorophosphate dichloromethane trisolvate], {[Cu(C6H4N2)(C39H32OP2)]PF6·3CH2Cl2}n, conventionally abbreviated as {[Cu(3-PyCN)(Xantphos)]PF6·3CH2Cl2}n, where Xantphos and 3-PyCN represent (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane) and pyridine-3-carbonitrile, respectively, has been described. In this polymer solvate, the asymmetric unit consists of three dichloromethane solvent molecules, a hexafluorophosphate anion and a polymeric heteroleptic cuprous complex cation, in which the cuprous centre is in a CuP2N2 tetrahedral coordination and is coordinated by two P atoms from the Xantphos ligand and two N atoms from two 3-PyCN ligands (the pyridyl and cyano N atoms). It is through the connection of the μ2-bridging 3-PyCN ligand that these cuprous centres are linked into a one-dimensional helical chain structure. The chains are further assembled through C-H...π interactions to form a supramolecular metal-organic framework containing solvent-accessible channels. The UV-Vis absorption and photoluminescence properties of this heteroleptic cuprous polymer have been studied on as-synthesized samples. Its luminescence emission should mainly originate from the metal-to-ligand charge transfer excited state.

Comparative Photovoltaics of P3HT:N2200 and P3HT: Small-Gap Fullerene Ethyl-Nipecotate Bulk Heterojunction Structures

This work deals with the study on the optical absorption and photoluminescence spectra of a p-type organic semiconducting polymer, regioregular poly 3-hexylthiophene-2,5-diyl (P3HT) and the absorption spectra of an n-type fullerene-based small-gap fullerene-ethyl nipecotate (Fullerene-EN) and a non-fullerene-based polynaphthalene bithiophene (N2200) semiconducting materials. The band gap of P3HT, N2200, and small-gap fullerene-ethyl nipecotate are 2.42, 1.65, and 1.51 eV, respectively, calculated from experimental results through the Tauc equation. Active layers with blends of P3HT and small-gap fullerene-ethyl nipecotate and P3HT and N2200 have been used to fabricate bulk heterojunction (BHJ) structures. The P3HT:N2200 BHJ structure follows the current density versus voltage characteristics of a photovoltaic device with 0.28% power conversion efficiency, 1.58 mA/cm2 short-circuit current density, and 41% fill factor. However, the P3HT:small-gap fullerene-ethyl nipecotate structure does not show any photovoltaic J–V characteristics.

Electrically switchable capabilities of conductive polymers-based plasmonic nanodisk arrays.

The electrically dynamic regulation of plasmonic nanostructures provides a promising technology for integrated and miniaturized electro-optical devices. In this work, we systematically investigate the electrical regulation of optical properties of plasmonic Au nanodisk (AuND) arrays integrated with different conductive polymers, polypyrrole (PPy), polyaniline (PANI), and poly(3,4-ethylenedioxythiophene) (PEDOT), which show their respective superiority of electrical modulation by applying the appropriate low voltages. For the hybrid structure of polymer-coated AuND arrays, its reflection spectrum and corresponding structural color are dynamically modulated by altering the complex dielectric function of the covering nanometer-thick conductive polymers based on the electrically controlled redox reaction. Due to the distinct refractive index responses of different polymers on the external voltage, polymer-coated AuND arrays exhibit different spectral variations, response time, and cycle stability. As a result, the reflection intensity of PPy-coated AuND arrays is mainly tailored by increasing optical absorption of the PPy polymer over a broad spectral range, which is distinguished from the wavelength shift of the resonance modes of AuND arrays induced by the other two polymers. Additionally, AuND arrays integrated with both PANI and PEDOT polymers exhibit a rapid switching time of less than 50 ms, which is 5 times smaller than the case of the PPy polymer. Most importantly, PPy-coated AuND arrays exhibit excellent cycle stability over 50 cycles compared to the other two polymers integrated devices. This work demonstrates a valuable technique strategy to realize high-performance polymer-coated dynamically tunable nanoscale electro-optical devices, which has especially significance for smart windows or dynamic display applications.

Drug Delivery Systems with a "Tumor-Triggered" Targeting or Intracellular Drug Release Property Based on DePEGylation.

Coating nanosized anticancer drug delivery systems (DDSs) with poly(ethylene glycol) (PEG), the so-called PEGylation, has been proven an effective method to enhance hydrophilicity, aqueous dispersivity, and stability of DDSs. What is more, as PEG has the lowest level of protein absorption of any known polymer, PEGylation can reduce the clearance of DDSs by the mononuclear phagocyte system (MPS) and prolong their blood circulation time in vivo. However, the “stealthy” characteristic of PEG also diminishes the uptake of DDSs by cancer cells, which may reduce drug utilization. Therefore, dynamic protection strategies have been widely researched in the past years. Coating DDSs with PEG through dynamic covalent or noncovalent bonds that are stable in blood and normal tissues, but can be broken in the tumor microenvironment (TME), can achieve a DePEGylation-based “tumor-triggered” targeting or intracellular drug release, which can effectively improve the utilization of drugs and reduce their side effects. In this review, the stimuli and methods of “tumor-triggered” targeting or intracellular drug release, based on DePEGylation, are summarized. Additionally, the targeting and intracellular controlled release behaviors of the DDSs are briefly introduced.

Characteristic and mechanism analysis of sludge polymer by adding carboxymethyl cellulose-g-acrylic acid for sludge utilization.

Herein, a nutrient water retention agent is prepared by fully mixing sludge with carboxymethyl cellulose-g-acrylic acid (CMC-g-AA) gel and nanoscale zero-valent iron (nZVI) using polymer modifying curing technology. Experimental results show that when CMC:AA = 1:12 and CMC-g-AA gel content is 50%, sludge polymer has better water absorption and retention performance and the water retention time is extended for ∼14 days. At the same time, sludge polymer can preserve the characteristics of nutrient-rich elements and organic matter and promote plant growth. The addition of nZVI has a significant impact on reducing the risk of heavy metal toxic leaching in sludge. Moreover, analysis of variance and multiple comparisons shows that sludge polymer's particle size and water absorption times have significant effects on the water absorption and retention properties of sludge polymer. Scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and 13C-nuclear magnetic resonance analyses show that the addition of an appropriate amount of gel could increase the number of hydrophilic groups and hydrophilic mineral components in sludge polymer, increase its overall porosity and improve its water absorption and retention properties.

Effects of different polymer hydrogels on moisture capacity of sandy soil

In arid and semi-arid regions, efficient utilization of available water necessitates the adaptation of appropriate water management practices. One such approach is through soil conditioners like polymer hydrogels. The application of polymer hydrogels aids efficient management of water in agricultural production by increasing water holding capacity and improving water conservation of sandy soils. This has led to practical applications of these materials particularly in arid regions and countries, where water is the limiting factor for plant production. Therefore, the ultimate objective of this study was to address the impacts of different polymer hydrogels such as potassium polyacrylate (PH1), starch-acrylonitrile (PH2), starch-acrylic-acid (PH3) and polyacrylic acid (PH4) on the moisture capacity of sandy soils from sand dune. The sandy soils contained >95% sand. Maximum rate of water absorption of polymers (PH1, PH2, PH3 and PH4) were 174, 38.75, 21.7 and 201.1 times their weight respectively. Four polymer hydrogels with three treatments (0.25:0.75, 0.5:0.5 and 0.75:0.25; v/v) were used in the experiment with four replication. With respect to the untreated soil, addition of polymer hydrogels increased significantly full moisture capacity (FMC) and smallest moisture capacity (SMC) for for all polymer: sand mixtures. PH1 recorded highest FMC and SMC than all four polymers. The results suggest that addition of a potassium polyacrylate to sandy soils is more effective polymer hydrogel at increasing moisture capacity in sandy soils.

Boosting the Optical Absorption of Melanin-like Polymers

Boosting the Optical Absorption of Melanin-like Polymers

Rapid chromium reduction by metal-free organic polymer photocatalysis via molecular engineering

The conversion of hexavalent chromium (Cr(VI)), a highly poisonous heavy metal found in natural environment, to less poisonous trivalent chromium (Cr(III)) has attracted a lot of interest. However, little interest has been paid to the development of metal-free catalysts. Here, we demonstrate for the first time a molecular engineering strategy to synthesize a range of donor-acceptor conjugated polymer photocatalysts, which can significantly increase the reduction efficiency of Cr(VI) by a factor of 5.2, corresponding to a significant change in the reduction reaction rate constant (from 0.0337 to 0.1740 min−1). In addition, the apparent quantum efficiency (AQE) of Cr(VI) removal was obtained, and the optimized photocatalyst (Py-SO1) could achieve the highest apparent quantum efficiency at wavelength of 420 nm in those samples. Despite the narrow light absorption of Py-SO1 polymer, its excellent exciton separation efficiency and efficient electron output enabled it to achieve excellent performance in photoreduction of Cr(VI), surpassing that of the reported metal-free photocatalysts. The results show that the present work provides a new perspective for designing suitable environmental remediation catalysts based on molecular engineering strategies.

An experimental protocol to study the membrane digestion and absorption of glucose polymers using everted sacs of rat small intestine

An experimental protocol to study the membrane digestion and absorption of glucose polymers using everted sacs of rat small intestine

Experimental Investigation on Aquatic Waste Water Hyacinth (Eichhorniacrassipes) Plant into Natural Fibre Polymer Composite – Biological Waste into Commercial Product

Present work dealt with evaluating the aquatic wastewater hyacinth plant long fibre reinforced withepoxy polymer composite mechanical strength, absorption, characterization, thermal degradation and stability, surface morphology studies. This research work water hyacinth long fibre is used as a reinforcement material and epoxy polymer matrix material is used as a matrix phase material. By utilizing the compression moulding hot press machine the different weight percentages (20, 25, 30, and 35%) of the hyacinth composite samples areproduced.Converting the biological waste into zero waste and useful product concept is achieved in this research. In this work hyacinth, long fibre is extracted with a new novel mechanical way (fabricated machine) of the extraction process. Hyacinth long fibre composite tensile strength (mechanical strength) is varied from 36.42 to 44.62MPa, flexural strength varied from 47.86 to 59.684MPa, and impact strength varied from 0.5 to 3.5J. After the 8th hour of monitoring the composite samples are attained constant values on both water and chemical absorption studies. By utilizing thermogravimetric analysis, x-ray diffraction method, Fourier transform infrared spectroscopy method the essential functional groups present in the hyacinth composites are identified. Based on the final experiment results the hyacinth fibre composite is highly recommended to the usage of profit oriented products.

How to Measure the Absorption and Desorption Curves of Superabsorbent Polymers in the Presence of Calcium Ions

The absorption and desorption curve of superabsorbent polymers (SAP), which reflects key information of the maximum absorbency and retention capacity, is crucial for the mix designs of internally cured concretes. In this paper, the effect of amount of Ca2+ on the absorption and desorption curve of SAP is studied. Results show that the proportion between amount of Ca2+ and SAP mass has a notable influence on the absorption and desorption curve of SAP, whether in tap water or mimicked pore solution of cement paste. Considering the important effect of amount of Ca2+, it is suggested that researchers need to determine the relationship between the retention capacity and the ratio of amount of Ca2+ to SAP mass in advance before formal measurement using classic tea bag method or filtration method. Furthermore, from the view of the ion exchange equilibrium between SAP and Ca2+, we discussed the mechanism that amount of Ca2+, concentration of Ca2+, SAP type, alkalinity, etc. have decisive effect on the absorption and desorption curve.

Regio‐regular and cross‐conjugated poly(thienylene vinylene)s through acyclic diene metathesis

AbstractPoly(thienylene vinylene)s (PTV's) are early examples of conjugated polymers but have not been extensively studied when compared with closely analogous polythiophenes. PTV's synthesized through previously reported techniques are similar in structures that contain various alkyl or alkoxy side‐chains that exert limited impact on the polymer electronic properties. Herein, we report the preparation of a series of regio‐regular PTV's (rr‐PTV's) bearing cross‐conjugated side‐chains through ADMET polymerization of a common brominated di(thienylene vinylene) (DTV) monomer followed by PPM reactions on the resulting brominated PTV. These new polymers contain a bulky silyloxy alkyl side‐chain and a functionalized thiophene moiety on every main‐chain thiophene unit, and their regio‐regular placement is confirmed by NMR spectroscopy. The thienyl based side‐groups broaden polymer absorption ranges and at the same time lead to uncommon emission properties that are results of light‐induced charge transfer events between the polymer main‐chains and side‐chains. Removal of the silyl groups on one of these rr‐PTV's led to insoluble materials and x‐ray diffraction experiments on the collected solids displayed distinct scattering peaks that are absent from similarly functionalized regio‐random PTV's reported previously, thus suggesting better crystallinity originated from regio‐regularity.

Inflammatory and regenerative processes in bioresorbable synthetic pulmonary valves up to two years in sheep–Spatiotemporal insights augmented by Raman microspectroscopy

In situ heart valve tissue engineering is an emerging approach in which resorbable, off-the-shelf available scaffolds are used to induce endogenous heart valve restoration. Such scaffolds are designed to recruit endogenous cells in vivo, which subsequently resorb polymer and produce and remodel new valvular tissue in situ. Recently, preclinical studies using electrospun supramolecular elastomeric valvular grafts have shown that this approach enables in situ regeneration of pulmonary valves with long-term functionality in vivo. However, the evolution and mechanisms of inflammation, polymer absorption and tissue regeneration are largely unknown, and adverse valve remodeling and intra- and inter-valvular variability have been reported. Therefore, the goal of the present study was to gain a mechanistic understanding of the in vivo regenerative processes by combining routine histology and immunohistochemistry, using a comprehensive sheep-specific antibody panel, with Raman microspectroscopy for the spatiotemporal analysis of in situ tissue-engineered pulmonary valves with follow-up to 24 months from a previous preclinical study in sheep. The analyses revealed a strong spatial heterogeneity in the influx of inflammatory cells, graft resorption, and foreign body giant cells. Collagen maturation occurred predominantly between 6 and 12 months after implantation, which was accompanied by a progressive switch to a more quiescent phenotype of infiltrating cells with properties of valvular interstitial cells. Variability among specimens in the extent of tissue remodeling was observed for follow-up times after 6 months. Taken together, these findings advance the understanding of key events and mechanisms in material-driven in situ heart valve tissue engineering. Statement of significanceThis study describes for the first time the long-term in vivo inflammatory and regenerative processes that underly in situ heart valve tissue engineering using resorbable synthetic scaffolds. Using a unique combinatorial analysis of immunohistochemistry and Raman microspectroscopy, important spatiotemporal variability in graft resorption and tissue formation was pinpointed in in situ tissue-engineered heart valves, with a follow-up time of up to 24 months in sheep. This variability was correlated to heterogenous regional cellular repopulation, most likely instigated by region-specific differences in surrounding tissue and hemodynamics. The findings of this research contribute to the mechanistic understanding of in situ tissue engineering using resorbable synthetics, which is necessary to enable rational design of improved grafts, and ensure safe and robust clinical translation.