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Colloid and Polymer Science
Journal Prestige (SJR): 0.597  Citation Impact (citeScore): 2 Number of Followers: 6  Hybrid journal (It can contain Open Access articles)ISSN (Print) 0303-402X - ISSN (Online) 1435-1536 Published by Springer-Verlag  [2468 journals]
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- Insights into BSA-micellar carrier-drug systems using pyrene excimer
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Abstract: The study investigates mixtures of bovine serum albumin (BSA) and micellar carriers with incorporated pyrene (Py). Mono-disperse hexaethyleneglycol mono n-dodecyl ether (C12E6) and respective, poly-disperse eicosaethyleneglycol mono n-tetradecyl ether (C14EO20) are employed to get micellar carriers with different dimension and polarity. Pyrene is used both as a probe and model drug to get insight upon the albumin-carrier association and the medicine transport. At BSA addition upon the drug-carrier system, the emissive signal and lifetime of Py excimer decrease, while the monomer lifetime increases. The results prove the transport of the probe in small micellar clusters on the polypeptide chain. Comparison of the quenching of BSA fluorescence by surfactant or/and Py unveils a hybrid process when both quenchers are present. In accord, a non-radiative fluorescence resonance energy transfer (FRET) occurs between BSA tryptophan and Py with higher donor–acceptor distance, the longer the carrier’s alkyl and ethyleneoxide chains. Pyrene predominantly forms dynamic excimers in all studied systems, which shows that the probe’s environment is fluid. The pyrene association ratio provided by UV–Vis absorption spectra indicates the transfer of some Py monomers only from the C12E6 micelles to nonpolar zones of protein. Differently, the long ethyleneoxide chains of C14EO20 impede the pyrene relocation. The Py-loaded micelles stabilize the secondary structure of BSA. The work sheds light on the transport of drugs with micellar carriers from alkyl-ethoxylated nonionic surfactants.
PubDate: 2023-05-27
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- Preparation of para-aramid aerogel fiber structurally colored by light
scattering through wet spinning and supercritical drying-
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Abstract: This research is an investigation of the preparation conditions for para-aramid aerogel fibers that are structurally colored by Rayleigh scattering, an angle-independent structural color. It is well known that structural color has the angle dependence of colors. However, there is currently a desire for materials with angle-independent structural color. During the fibers’ spinning process, the microstructures of the fibers are generated. The effect of spinning conditions is investigated by measuring the optical properties of the wet gel fibers. The neutralization speed of negatively charged PPTA fibrils has a significant impact on the formation of the dense microstructure. Spinning under the fast neutralization speed condition makes it possible to achieve the blue-colored fiber derived from Rayleigh scattering. The influence of neutralization speed on the microstructure of the fibers is confirmed by FE-SEM characterization. Furthermore, spinning using a narrow inner diameter needle decreases the whiteness component derived from Mie scattering of the fibers, resulting in a more vivid blue color. The angle-independent structurally colored fibers hold great promise for application in clothing, interiors, and industrial materials.
PubDate: 2023-05-25
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- Evaluation of the ageing resistance and lifespan of talc-filled
poly(butylene adipate-co-terephthalate)/polylactide (PBAT/PLA) films used
for winter potato cultivation-
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Abstract: Evaluating the lifespan of aged biodegradable mulch films from the perspective of realistic outdoor climate conditions is a challenge. However, it is worthwhile to determine the changes in their structure and stability. In this study, a talc-filled black poly (butylene adipate-co-terephthalate)/polylactide (PBAT/PLA) biodegradable mulch film was designed and mulched with shallow overburden soil to improve the anti-weathering characteristics of winter potatoes grown in southern China. This study focused on the weather resistance properties of biodegradable talc-filled PBAT/PLA-based mulch films. After 4 months of outdoor service, the elongation at break and tensile strength of talc-filled black PBAT/PLA films remained at 360 ± 250% and 15 ± 2.5 Mpa, respectively, with the number average molecular weight decreasing by 21.4% and the gel content increasing to 10%. Combining the results of microstructure analyses, molecular weight changes, thermodynamic properties, and mechanical and structural changes due to accelerated ageing under different indoor conditions, it was concluded that the maintenance of the mechanical properties of the mulch films could be attributed to the inhibition of random chain-breaking and heavy photo-crosslinking in the plastic film system. Our results using biodegradable films based on crop growth characteristics provide an effective strategy for extending the service life of biodegradable plastics and reducing the cost of biodegradable mulch films. Graphical
PubDate: 2023-05-25
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- 3D-printed layer-by-layer electrode graphene/poly(1,8-diaminonaphthalene)
incorporated with silver nanoparticles as an electrochemical sensing
platform for cefepime antibiotic determination-
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Abstract: This article presents a new electrode made with a 3D printer which is coated with a layer of graphene oxide and poly(1,8-diaminonaphthalene) combined with silver nanoparticles as an electro-catalyst for the detection of the antibiotic cefepime, an important fourth-generation cephalosporin. This nanocomposite-based 3D printing electrode showed an enhanced electrocatalytic activity toward cefepime with high sensitivity and stability in neutral pH media. The linear relationship between the height of peak current and cefepime concentration allowed the differential pulse voltammetry determination of cefepime from 0.4 to 4.0 μM, and the limit of detection was 0.08 μM. The proposed electrode was successfully applied for the determination of cefepime as the drug in pharmaceutical formulations sample.
PubDate: 2023-05-24
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- Evaluation of interaction forces between hydrophobic surfaces in
surfactant solutions by atomic force microscopy-
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Abstract: The interaction forces between silica surfaces with various degrees of hydrophobicity were measured using colloidal probe atomic force microscopy to clarify the relationship between the hydrophobicity of the surfaces and hydrophobic attraction in detail. The interaction forces between silica surfaces pre-hydrophobised with octadecyltrichlorosilane were measured in aqueous solutions with three different (cationic, anionic, and nonionic) surfactants. Hydrophobic attraction was observed between surfaces from 10 to 15 nm without surfactant, and the range of this attraction decreased when the surface hydrophobicity decreased with increasing surfactant concentration. The hydrophobic attraction disappeared when the surface contact angle was below 80°–90° in the presence of all surfactants used in this study. The range of the hydrophobic attraction was found to depend strongly on the contact angle and not on the surfactant type and concentration. The adhesion force was also highly dependent on the contact angle and comparable to the theoretical capillary force. The possible origin of this force is discussed with reference to the obtained results. Graphical
PubDate: 2023-05-23
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- Effect of carbons’ structure and type on AC electrical properties of
polymer composites: predicting the percolation threshold of permittivity
through different models-
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Abstract: The AC electrical properties of EVA- and NBR-based composites filled with different conductive fillers were investigated. Result shows several magnitudes of increment in AC electrical conductivity and dielectric permittivity after the addition of these conductive fillers, indicating that these materials can be used as supercapacitors. The magnitude of increment was varied according to polymer and filler types. Herein, we also have tested the applicability of different sigmoidal models to find out the percolation threshold value of permittivity for these binary polymer composite systems. It is observed that except sigmoidal–Boltzmann and sigmoidal–dose–response models, other sigmoidal models exhibit different values of percolation threshold when considered for any particular polymer composite system. The paper discusses the variation in results of percolation threshold with an emphasis on the advantages, disadvantages and limitations of these models. We also have applied the classical percolation theory to predict the percolation threshold of permittivity and compared with all the reported sigmoidal models. To judge the unanimous acceptability of these models, they tested vis-à-vis the permittivity results of various polymer composites reported in published literature. To comprehend, all the models except the sigmoidal–logistic-1 model were successfully applicable for predicting the percolation threshold of permittivity for polymer composites.
PubDate: 2023-05-23
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- Quantitative investigation of the pore size–reducing effect of
perfluorocarbons in polyurethane foaming-
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Abstract: Despite the long-standing use of per- and polyfluorinated carbons (FCs) as pore size–reducing agents for polyurethane rigid (PUR) foams, their mechanisms of action remain poorly understood. To shed light on these mechanisms, we provide a quantitative analysis of the influence of the FC concentration on the pore size of PUR cup foams of two different model PUR foam systems: an industrially-relevant “technical system” and a simplified “scientific system.” Combining scanning electron microscopy (SEM) and the PORE!SCAN method, we provide a detailed analysis of the pore size distributions of the obtained foams. We confirm that the characteristic pore size of both systems is indeed significantly reduced by adding small quantities of FC. However, we show that there seems to exist a critical FC concentration (about 3 wt.% with respect to the A-component) beyond which adding more FC has a negligible effect. More interestingly, the relative extent of the pore size reduction is almost identical for both PUR foam systems and the normalized pore size distributions remain largely unchanged over the whole range of FC concentrations. Our findings suggest that the FC-driven pore size reduction is a general effect caused by distinct mechanisms that are independent of the choice of the PUR foam system. Moreover, we hypothesize that this effect is not to be searched for during foam aging, as often reported, but during the pre-mixing step.
PubDate: 2023-05-22
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- Aggregation and disaggregation of Al2O3 nanoparticles: influence of
solution pH, humic acid, and electrolyte cations-
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Abstract: Extensive use of Al2O3 nanoparticles in consumer and industrial products has led to concerns about their potential environmental impacts in the recent years. In most studies concerning Al2O3 aggregation and disaggregation, more was to consider the single factor that influences their environmental behaviors. Understanding the combined abiotic factors that influence the fate, transport, and stability of nanoparticles in a complex aquatic system has become extremely important. Here, we reported and analyzed the major abiotic factors such as typical solution pH, electrolyte cations in different valences (Na+ and Ca2+), and the presence of humic acid (HA) that influence the stability, aggregation, and disaggregation behaviors of Al2O3 nanoparticles in a complex aquatic system. Dynamic light scattering technique combined with fluorescence spectroscopic analysis was used to explore the aggregation mechanisms. Experimental results indicated that Al2O3 nanoparticle stability was mainly controlled by the steric hindrance, van der Walls, and electrostatic interactions between HA and Al2O3 nanoparticles. Aggregation kinetics and attachment efficiency studies induced by the addition of Na+ and Ca2+ cations confirmed that divalent electrolytes could reduce the large energy barrier between the charged colloidal particles more efficiently, and induce a more aggressive aggregation of the particles. Additionally, the bridging effect of HA with Ca2+ was also an important mechanism for the aggregation enhancement, which had been confirmed by the fluorescence excitation-emission matrix (EEM) spectra analysis. These findings are useful in understanding the environmental challenges of inorganic colloidal particles in natural environments.
PubDate: 2023-05-22
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- Light-induced reversible destabilization of responsive latex particles
prepared via high solids content emulsion polymerization-
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Abstract: Aqueous dispersions of polymer nanoparticles (latexes) are of high commercial importance — it can be desirable to reversibly destabilize such latexes, for example, to enable transport/storage without the significant weight fraction of the water. In the present work, we have employed ab initio emulsion polymerization of methyl methacrylate with industrially relevant high solids content using mixtures of the anionic surfactant sodium dodecyl sulfate (SDS) and the photo-switchable cationic surfactant 2-(4-(4-butylphenyl)diazenylphenoxy)ethyltrimethylammonium bromide (C4AzoTAB). C4AzoTAB contains an azobenzene moiety that can undergo trans–cis isomerization triggered by UV light, the cis form being a less effective surfactant than the trans form. Rapid destabilization (sedimentation) could be achieved on exposure of the diluted latex to UV light using a continuous flow device, and subsequent redispersion was obtained on exposure to visible light, demonstrating reversibility of the process. The presence of the anionic SDS as well as judicious choice of the amphoteric initiator VA-057 play key roles in designing successful destabilization, with latex pH being of crucial importance.
PubDate: 2023-05-20
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- Phase behavior and structure of a biocompatible microemulsion based on
Tween 20, 2-ethylhexylglycerine and isopropyl palmitate in water-
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Abstract: Microemulsions are thermodynamically stable mixtures of water and oil. For many applications, such as in cosmetics, it is important that the components are biocompatible. For the formulation of a new biocompatible microemulsion based on Tween 20 (Tw20) surfactant, the glycerol ether 2-ethylhexylglycerin (EHG) is employed as an alternative to commonly used short- to medium chain alcohols as cosurfactant. Tw20 itself is not capable of any significant solubilization but the addition of EHG allows to enhance the solubilization capacity for the polar oil isopropyl palmitate (IPP) largely. At a Tw20 to EHG molar ratio of 1:12, i.e., very large excess of cosurfactant, the solubilization capacity is increased by nearly three orders of magnitude compared to a pure Tw20 solution. The resulting oil-in-water (O/W) microemulsion is studied using static and dynamic light scattering (SLS/DLS) and small-angle neutron scattering (SANS). The SANS spectra are analyzed with a core–shell ellipsoid model, which indicates formation of oblate droplets at higher EHG content. Dynamic light scattering experiments confirm the presence of microemulsion droplets with hydrodynamic radii increasing from 3.8 to 19.8 nm upon addition of cosurfactant. In summary, this study shows that EHG is a cosurfactant that enhances the solubilization properties of a biocompatible surfactant largely and thereby renders it very useful for formulations.
PubDate: 2023-05-15
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- Stepwise self-assembly of bottlebrush random copolymers into uniform
cylindrical structures-
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Abstract: Controllable self-assembly of copolymers in solutions offers an effective tool for constructing functional nanostructures. However, achieving the stepwise assembly of copolymers in solutions remains challenging. In this study, we report the fabrication of cylindrical microstructures through the stepwise self-assembly of bottlebrush random copolymers (BBRPs) in solutions. The BBRPs were synthesized via a combination of “grafting-through” and “grafting-from” strategies. The assembly of BBRPs yielded spherical micelles in a mixture of dioxane and water, which further transformed into uniform cylindrical microstructures by dialyzing the solution against water. The cylinders could be obtained within a relatively large range of parameters, such as length ratios of hydrophilic/hydrophobic blocks, volume fractions of water, and copolymer concentrations. This work provides new insights into the assembly behavior of BBRPs and the preparation of cylindrical structures for applications in such as templated synthesis of hybrid materials.
PubDate: 2023-05-09
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- Facile fabrication of superhydrophilic poly(styrene-co-acrylate)/SiO2
composite materials by conventional emulsion polymerization-
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Abstract: A novel procedure for the preparation of superhydrophilic poly(styrene-co-acrylate)/SiO2 composite materials was prepared from conventional emulsion polymerization in the presence of colloidal silica. TEM photos revealed that poly(styrene-co-acrylate) latexes exhibited a clear core–shell structure, and the electrostatic repulsion and hydrogen bonds between poly(styrene-co-acrylate) latexes and SiO2 nanoparticles guaranteed the uniform dispersion of silica nanoparticles. The average diameter data indicated that the particle size of composite latexes (78 nm) was slightly smaller than that of polymer (82 nm), although the slight aggregation of SiO2 nanoparticles had increased the average diameter to 87 nm. FTIR spectra confirmed that hydrogen bonds were formed and gel reaction of –OH groups occurred during film formation. Two kinds of Si–O bonds were found in XPS spectra with a weight ratio addition of 20.0% SiO2, which one was related to the Si–OH groups of colloidal silica nanoparticles, while the other was attributed to the Si–O-Si groups obtained from the gel reaction. SEM and AFM images displayed that the formation of micro/nano structure from the gel reaction had increased the roughness of the composite films. The water contact angle (WCA) of the composite films was found to decrease from 45 to 3º (3 s) and exhibit superhydrophilicity. Graphical abstract
PubDate: 2023-05-05
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- Modification on crystallization behavior and mechanical properties of
polylactide by the addition of polyamide elastomer-
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Abstract: The phase morphology, crystallization behavior, and mechanical properties of polylactide (PLA) modified by polyamide elastomer (PAE) have been systematically investigated. SEM images showed that PAE was homogeneously dispersed in the PLA matrix forming a sea-island morphology. The dimension of PAE domains increased slightly with its content and still remained smaller than 3 μm even at 40 wt% due to the partial compatibility of PLA and PAE. PAE had some nucleation effect on PLA and promoted the crystallization of PLA to a certain extent. The crystallization kinetics and crystalline morphology, especially the nucleation and growth of PLA crystals, were compared in detail between pure PLA and PLA/PAE blends. The elongation at break and impact strength of PLA were considerably improved by PAE. The sample PAE20 exhibited the best rigidity-toughness balance showing ductile failure. The toughening mechanism was proposed based on the deformation of the impact fracture surfaces.
PubDate: 2023-05-05
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- SERS scaffold based on silver nanoparticles with multi-ingredient heavy
metal ligands for the determination of Mn(II)-
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Abstract: Heavy metal ions are difficult to determine directly by surface-enhanced Raman spectroscopy (SERS) due to the lack of Raman characteristic peaks for heavy metal. Herein, a SERS platform was promoted for the determination of divalent manganese ion (Mn2+) with the properties of cost-effectiveness and simplicity. The SERS platform was constructed into a hybrid system of silver nanoparticles (AgNPs), 6-mercaptonicotinic acid (MNA), and melamine (MA). The likely principle of the SERS analysis platform for Mn2+ is that 6-mercaptonic acid cooperates with melamine to combine manganese ions to cause the aggregation of silver nanoparticles, resulting in the rapid enhancement of Raman characteristic peak signals of 6-mercaptonic acid. The established SERS platform for the Mn2+ determination obtained good linearity in the range of Mn2+ concentration of 1.0 × 10−5–1.0 × 10−4 mol/L with a limit of detection (LOD) of 4.0 × 10−6 mol/L.
PubDate: 2023-05-04
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- Facile preparation of magnetic P(MMA-co-GMA)@Fe3O4@PMAA microspheres using
porous microsphere as templates for removal of methylene blue-
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Abstract: Magnetic polymer microspheres (MPMs) have been frequently used in contemporary wastewater treatment technology because of their efficient adsorption and separation capabilities. However, the magnetization efficiency of polymer microspheres cannot be effectively enhanced using the reported template methods. In this study, a novel template method for preparing MPMs was developed. Magnetic P(MMA-co-GMA)@Fe3O4@PMAA microspheres (mPFPMs) were created with a high magnetic content, homogeneous particle size distribution, and carboxylated surfaces. Compared with the conventional template methods, this method avoids the generation of free magnetic nanoparticles and improves the magnetic content of MPMs, as well as imparting carboxyl functional groups to the mPFPMs. The mPFPMs can be used to adsorb contaminants quickly and effectively. The results of the adsorption process were preferably fitted to the Langmuir isotherm (R2 = 0.998) with a maximum adsorption capacity of 124.9 mg/g and followed the pseudo-second-order kinetic model. Besides, the mPFPMs adsorbent showed better reusability for ten cycles with high adsorption properties. Therefore, this work proposed a novel and facile strategy to prepare MPMs that exhibited significant potential application value in many fields.
PubDate: 2023-05-03
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- Correction to: Analysis of cellulose extracted from waste products
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PubDate: 2023-04-28
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- Surface freezing of CTAC-hexadecane mixed adsorbed film at the isopropyl
palmitate–water interface: a way to stabilize emulsions-
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Abstract: In this study, we utilized the surface freezing transition of mixed adsorbed films of cetyltrimethylammonium chloride (CTAC) and hexadecane at the isopropyl palmitate (IPP)–aqueous interface to encapsulate IPP in a stable oil-in-water (OW) emulsion droplets. IPP is a widely used emollient oil in cosmetic creams; however, as often seen in oily ingredients in cosmetics, it is also surface-active and adsorbs at the oil–water interface. Therefore, under normal experimental conditions, surfactant emulsifier and cosmetic oil form a mixed adsorbed film at the OW emulsion surfaces. However, such films typically do not enhance emulsion stability and for that purpose we used a 1:9 mixture of hexadecane and IPP as oil phase together with CTAC as surfactant. The interfacial tension of the oil phase against CTAC aqueous solution as a function of CTAC concentration and temperature shows three distinctive interfacial phases: disordered mixed adsorbed film of CTAC and IPP (surface liquid) and two surface frozen monolayers in which CTAC or IPP expelled the other and gives rise to a highly ordered and stiff hydrocarbon chain layer with incorporated hexadecane molecules. The compositional transition of the surface frozen monolayer of IPP and that of CTAC occurred as the CTAC concentration increased in the aqueous phase. Above the transition concentration, an enhanced OW emulsion stability was observed, whereas IPP surface frozen monolayer forms only kinetically unstable emulsions. From these findings, we suggest the potential use of surface frozen films of CTAC to encapsulate surface-active cosmetic oils stably in the OW emulsions, which in addition have the property that the stability can be controlled by temperature. Graphical
PubDate: 2023-04-28
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- Co-micellization conduct and structural dynamics of block copolymers in
water and salt solution environment for drug solubilization enhancement-
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Abstract: The present study examines the co-micellization in different block copolymers (BCPs): P123 and F127 (with almost similar hydrophobic PO block but different hydrophilic %EO content). In varying concentration and in presence of NaCl, these BCP solutions in single and mix system displayed a variety of phases, i.e., blue point (BP), thermoreversible gel formation and cloud point (CP) with a noticeable sol–gel phase transition shift. The nanoscale micellar size distribution expressed as hydrodynamic diameter (Dh) was evaluated using dynamic light scattering (DLS). As F127 is larger than P123 and contains more EO groups, the micelle corona appears larger with greater Dh. The scattering profile from small-angle x-ray scattering (SAXS) offered information into the micellar dimensions employing SasView 4.2.2 program. The quercetin (QCT) solubilization articulated in encapsulation efficiency (EE%) and drug loading (DL%) followed the enhancement order: P123 > (P123 + F127) > F127 which was inferred from spectral and microscopy study. Graphical 5%w/v Pluronics® (P123 and F127) in single (pure) and mix environment depicting their micellar dimensions obtained from SAXS.
PubDate: 2023-04-27
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- Fabrication of liner low-density polyvinyl-based carbon fibers via
ultraviolet irradiation-vulcanization crosslinking-
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Abstract: In this paper, the linear low-density polyethylene (LLDPE) fibers were used as the precursors to prepare low-cost carbon fibers (CFs) via ultraviolet crosslinking-vulcanized stabilization-carbonization processing. The spinning particles were obtained by mixing linear low-density polyethylene with photoinitiator 4-chlorobenzophenone (4-CBP), crosslinkers triallyl isocyanurate (TAIC), and thermal stabilizer antioxidant 1010, and then the ultraviolet (UV) photosensitive LLDPE fibers were fabricated by traditional melt spinning. Then, the LLDPE primary fibers were treated by UV irradiation, vulcanized stabilization and carbonization to obtain the low-cost CFs. to characterize the structure and properties of ultraviolet crosslinked polyethylene (UV-XLPE) fibers and CFs, the Fourier transform infrared spectrometer, differential scanning calorimeter, thermogravimetric analyzer, X-ray diffractometer and scanning electron microscope were adopted. The results showed that, UV irradiation introduced a crosslinked structure of LLDPE fibers, and the degree of gelation of XLPE fibers reached a maximum of 48.6% when UV irradiation was carried out for 15 min; with the extension of UV irradiation time, the melting temperature and crystallization temperature of UV-XLPE fibers move to the direction of low temperature, and the crystal size of the fiber decreases; after vulcanization, the carbon yield of the fiber is significantly improved, reaching up to 62.9%, and the surface and section of CFs are dense.
PubDate: 2023-04-25
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- Cation release from different carboxymethyl cellulose hydrogels
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Abstract: Biodegradable hydrogels have great potential in agriculture. In this study, hydrogel prototypes of biodegradable slow-release fertilizers were formulated by a Schiff base reaction between dialdehyde carboxymethyl cellulose and gelatin. The release behavior of iron cations from these carboxymethyl cellulose-based hydrogels with different degrees of substitution was studied. The analyses of the relation between correlation length of the cross-linked hydrogels and the degree of substitution, i.e., the amount of negatively charged positions in the hydrogels, allowed to determine the influence of structure and electrostatic interaction on cation release kinetics, which was successfully described by Peleg’s Model. The hydrogel with the lowest degree of substitution reveals the slowest release of cations due to the smallest correlation length. These results demonstrate that the correlation length is dominant for the release of divalent cations. Moreover, this also shows the potential of the DACMC-Gelatin hydrogels as matrix for slow-release fertilizers.
PubDate: 2023-04-24
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