Ideal Polymer Research Articles

Linking Electronic and Structural Disorder Parameters to Carrier Transport in a Modern Conjugated Polymer.

Understanding charge transport in conjugated polymers is crucial for the development of next-generation organic electronic applications. It is presumed that structural disorder in conjugated polymers originating from their semicrystallinity, processing, or polymorphism leads to a complex energetic landscape that influences charge carrier transport properties. However, the link between polymer order parameters and energetic landscape is not well established experimentally. In this work, we successfully link statistical surveys of the local polymer electronic structure with paracrystalline structural disorder, a measure of statistical fluctuations away from the ideal polymer packing structure. We use scanning tunneling microscopy/spectroscopy to measure spatial variability in electronic band edges in PM6 films, a high-performance conjugated polymer, and find that films with higher paracrystallinity exhibit greater electronic disorder, as expected. In addition, we show that macroscopic charge carrier mobility in field effect transistors and and trap influence in hole-only diode devices is positively correlated with these microscopic structural and electronic parameters.

Analytical and Numerical Investigation of Star Polymers in Confined Geometries.

The analysis of the impact of the star polymer topology on depletion interaction potentials, depletion forces, and monomer density profiles is carried out analytically using field theory methods and techniques as well as molecular dynamic simulations. The dimensionless depletion interaction potentials and the dimensionless depletion forces for a dilute solution of ideal star polymers with three and five legs (arms) in a Θ-solvent confined in a slit between two parallel walls with repulsive surfaces and for the case where one of the surfaces is repulsive and the other inert are obtained. Furthermore, the dimensionless layer monomer density profiles for ideal star polymers with an odd number (f˜ = 3, 5) of arms immersed in a dilute solution of big colloidal particles with different adsorbing or repelling properties in respect of polymers are calculated, bearing in mind the Derjaguin approximation. Molecular dynamic simulations of a dilute solution of star-shaped polymers in a good solvent with N = 901 (3 × 300 + 1 -star polymer with three arms) and 1501 (5 × 300 + 1 -star polymer with five arms) beads accordingly confined in a slit with different boundary conditions are performed, and the results of the monomer density profiles for the above-mentioned cases are obtained. The numerical calculation of the radius of gyration for star polymers with f˜ = 3, 5 arms and the ratio of the perpendicular to parallel components of the radius of gyration with respect to the wall orientation for the above-mentioned cases is performed. The obtained analytical and numerical results for star polymers with an odd number (f˜ = 3, 5) of arms are compared with our previous results for linear polymers in confined geometries. The acquired results show that a dilute solution of star polymer chains can be applied in the production of new functional materials, because the behavior of these solutions is strictly correlated with the topology of polymers and also with the nature and geometry of confined surfaces. The above-mentioned properties can find extensive practical application in materials engineering, as well as in biotechnology and medicine for drug and gene transmission.

Supersoft Polymer Melts in Binary Blends of Bottlebrush cis-1,4-Polyfarnesene and cis-1,4-Polyisoprene.

Binary blends of polyterpenes are employed comprising cis-1,4-polyfarnesene (PF) with a bottlebrush architecture, and linear cis-1,4-polyisoprene (PI) as model systems toward supersoft polymer melts. The bottlebrush PF results in a low plateau modulus ( Pa) that can further be reduced with the addition of PI. Depending on the fraction of short PI chains in the athermal and nearly isofrictional blends, plateau moduli in the range from 1 to 10kPa can be achieved. Tube dilation is very efficient in the present binary blends as compared to more common blends comprising long/short or linear/star chains of identical polymer structure.

Effect of active loop extrusion on the two-contact correlations in the interphase chromosome.

The population-averaged contact maps generated by the chromosome conformation capture technique provide important information about the average frequency of contact between pairs of chromatin loci as a function of the genetic distance between them. However, these datasets do not tell us anything about the joint statistics of simultaneous contacts between genomic loci in individual cells. This kind of statistical information can be extracted using the single-cell Hi-C method, which is capable of detecting a large fraction of simultaneous contacts within a single cell, as well as through modern methods of fluorescent labeling and super-resolution imaging. Motivated by the prospect of the imminent availability of relevant experimental data, in this work, we theoretically model the joint statistics of pairs of contacts located along a line perpendicular to the main diagonal of the single-cell contact map. The analysis is performed within the framework of an ideal polymer model with quenched disorder of random loops, which, as previous studies have shown, allows us to take into account the influence of the loop extrusion process on the conformational properties of interphase chromatin.

Viscoelastic and Birefringence Relaxation of Individualized Cellulose Nanofibers in the Dilute and Semidilute Regions.

Viscoelastic relaxation mechanisms of individualized cellulose nanofibers (iCNFs) dispersed in glycerol in the dilute and semidilute regions were investigated by linear viscoelastic and dynamic birefringence measurements. The birefringence relaxation of the iCNFs was described by the orientational and curvature modes of an existing viscoelastic theory for ideal semiflexible polymers (Shankar-Pasquali-Morse theory). However, the Shankar-Pasquali-Morse theory could not fully describe the iCNF viscoelastic relaxation at high frequencies. Considering the results for birefringence relaxation, the experimental tension mode of the iCNFs was evaluated to be higher than the theoretical value. These results show that the viscoelastic relaxations of the iCNFs are different from those of ideal semiflexible polymers, in contrast to cellulose nanocrystals (CNCs). As the iCNF concentration increased, the orientational mode dramatically slowed, which was more drastic than other semiflexible polymers, including CNCs. This anomalous behavior is likely due to the nonideal nature of iCNFs.

Chemical Recycling of Poly(cyclohexene carbonate)s via Synergistic Catalysis.

Chemical recycling of polymers to the corresponding monomers offers a valuable solution to address the current plastics crisis for creating an ideal and circular polymer economy. Here, we present a bimetallic synergistic depolymerization of the widely studied CO2-based polycarbonates, poly(cyclohexene carbonate)s, to epoxide monomers efficiently. The bimetallic CrIII-complex-mediated highly selective depolymerization and repolymerization was achieved via the regulation of reaction temperature, thus closing the circular loop of poly(cyclohexene carbonate)s in situ. Mechanistic investigation has revealed that the formation of epoxides undergoes a direct chain-end unzipping process. A bimetallic catalysis involving a nucleophilic attack of the metal-alkoxide species toward the methine carbon atom bound with an adjacent carbonyl that is activated by the other metal center features a lower energy barrier in DFT calculations, which promotes the epoxide extrusion.

Hybridization of Polymer-Encapsulated MoS2-ZnO Nanostructures as Organic-Inorganic Polymer Films for Sonocatalytic-Induced Dye Degradation.

The development of environmentally friendly technology is vital to effectively address the issues related to environmental deterioration. This work integrates ZnO-decorated MoS2 (MZ) to create a high-performing PVDF-based PVDF/MoS2-ZnO (PMZ) hybrid polymer composite film for sonocatalytic organic pollutant degradation. An efficient synergistic combination of MZ was identified by altering the ratio, and its influence on PVDF was assessed using diverse structural, morphological, and sonocatalytic performances. The PMZ film demonstrated very effective sonocatalytic characteristics by degrading rhodamine B (RhB) dye with a degradation efficiency of 97.23%, whereas PVDF only degraded 17.7%. Combining MoS2 and ZnO reduces electron-hole recombination and increases the sonocatalytic degradation performance. Moreover, an ideal piezoelectric PVDF polymer with MZ enhances polarization to improve redox processes and dye degradation, ultimately increasing the degradation efficiency. The degradation efficiency of RhB was seen to decrease while employing isopropanol (IPA) and p-benzoquinone (BQ) due to the presence of reactive oxygen species. This suggests that the active species •O2- and •OH are primarily responsible for the degradation of RhB utilizing PMZ2 film. The PMZ film exhibited improved reusability without substantially decreasing its catalytic activity. The superior embellishment of ZnO onto MoS2 and effective integration of MZ into the PVDF polymer film results in improved degrading performance.

Depletion potential, correlation functions and demixing transition in model colloid-polymer mixtures

We describe a theoretical framework to calculate depletion potential between colloid particles induced by non-adsorbing ideal polymer chains (s-species) and correlation functions in a coarse-grained one-component system of colloids (c-species). A Padé approximant is used to express the depletion potential as a pair potential with many-body contributions subsumed in it. The depletion potential and correlation functions of c-species are calculated using a self-consistent procedure. Results for several values of size ratio q=σsσc (σs and σc are, respectively diameters of the polymer chain and a colloid particle) and packing fractions of s- and c-species are reported. The spinodal curve and critical point of demixing transition are determined for several values of q. Calculated values are compared with values found from other theories and simulations.

Motorized chain models of the ideal chromosome

An array of motor proteins consumes chemical energy in setting up the architectures of chromosomes. Here, we explore how the structure of ideal polymer chains is influenced by two classes of motors. The first class which we call "swimming motors" acts to propel the chromatin fiber through three-dimensional space. They represent a caricature of motors such as RNA polymerases. Previously, they have often been described by adding a persistent flow onto Brownian diffusion of the chain. The second class of motors, which we call "grappling motors" caricatures the loop extrusion processes in which segments of chromatin fibers some distance apart are brought together. We analyze these models using a self-consistent variational phonon approximation to a many-body Master equation incorporating motor activities. We show that whether the swimming motors lead to contraction or expansion depends on the susceptibility of the motors, that is, how their activity depends on the forces they must exert. Grappling motors in contrast to swimming motors lead to long-ranged correlations that resemble those first suggested for fractal globules and that are consistent with the effective interactions inferred by energy landscape analyses of Hi-C data on the interphase chromosome.

Statistics of Gaussian polymer chains in harmonic applied fields.

The model of an ideal polymer chain in a harmonic applied field has broad applicability in situations involving polymer confinement and deformation due to applied stress. In this work we (1) formulate a general analytical model for a continuous Gaussian chain under a harmonic applied potential and (2) evaluate the statistical mechanics of this model given the potential, obtaining partition functions and moment generating functions (MGFs) that describe the chain configurations. Closed-form expressions for the squared radius of gyration, potential energy, partition function, and MGF for the center of mass are obtained for a general and multidimensional harmonic field. The expressions are compared with results of Monte Carlo simulations of a discrete Gaussian chain as well as results for related systems obtained from the literature. The theory derived here is used to test the applicability of the current model assumptions to relations from the literature describing polymer confinement and deformation in experiment, theory, and simulations.

Zinc oxide nanoparticles immobilized on polymeric porous matrix for water remediation

This work proposes a novel approach to producing composite membranes by immobilizing and blending ZnO nanoparticles within a polymer matrix. The focus is investigating how different immobilization techniques impact membrane performance in critical technological applications, including membrane fouling mitigation and photocatalytic degradation. Lab-synthesized ZnO nanostructures were immobilized within a natural cellulose acetate (CA) matrix using a spray coating technique. To ensure comprehensive exploration, CA membranes with 12% and 15% wt polymer concentrations, which demonstrated superior overall performance in previous studies, were cast and prepared. The membranes underwent phase inversion, and a specially prepared ZnO solution was sprayed onto the membrane surface, creating a unique blend of polymer and nanoparticles. This comparative study highlights distinctions between nanomaterial immobilization techniques (mixing and spray coating) while maintaining identical polymer content. Such insights are crucial for both industrial applications and laboratory-scale research. The photocatalytic degradation of the reactive and toxic dye methylene blue (MB) served as a model reaction, employing a UV light module. Results unequivocally demonstrated that, irrespective of the immobilization technique employed, the combination of CA and ZnO nanoparticles significantly enhanced the photocatalytic activity of the membrane in degrading methylene blue (MB). Specifically, the dye concentration decreased from 25 to approximately 8 mg/L for both the spray coating and bulk immobilization methods, resulting in 62% and 69% dye degradation, respectively. These findings underscore the versatility of different immobilization techniques in various aspects of membrane technology. The CA-ZnO composite exhibited efficacy in photocatalytic MB degradation tests, offering promising alternatives for designing polymeric membranes tailored for contaminant removal, particularly in treating textile dye-contaminated aqueous solutions. The exploration of diverse immobilization techniques for nanocomposites presents an exciting avenue for optimization in different membrane technological processes.

PSII-3 Evaluation of a microneedle patch for the delivery of meloxicam in a veterinary application

Abstract In the livestock industry, animals undergo painful procedures such as castration and these practices have received increased scrutiny and concern regarding animal welfare. Nonsteroidal anti-inflammatory drugs (NSAIDs) have been used to treat pain and inflammation in livestock. Novel administration routes such as transdermal drug delivery using polymeric biodegradable microneedle patches that are being developed to deliver drugs in a less stressful method. Therefore, the objective of this study was to evaluate meloxicam plasma concentrations when drug was delivered using a microneedle patch. Nursing pigs (n = 7; body weight = 3.69 ± 1.12 kg) from 1 litter were stratified into 1 of 3 treatment groups. Treatments were: 1) 0.5 mg of meloxicam/kg of body weight via oral drench (n = 2; oral); 2) a patch devoid of meloxicam (n = 1; placebo); or 3) 2.5 mg of meloxicam/kg of body weight delivered via microneedle patch (n = 4; patch). During the study, pigs remained in the crate with the sow and littermates. Blood was collected via jugular venipuncture for plasma analysis at 0, 8, 24, 48, and 72 h. An Estrotect Breeding Indicator strip was used to adhere the microneedle patch on the ear of the pigs. Briefly, the strip was cut to the size of the ear, a microneedle patch was placed at the center, and these were applied on the pinna of the ear after blood collection at 0 h. Statistical analyses were performed using the MIXED procedure of SAS 9.4 (Cary, NC) to assess the effects of treatment, time, and treatment × time interaction. Statistical significance was determined at P ≤ 0.05, with tendencies at 0.05 < P ≤ 0.1. There was a treatment × time interaction (P = 0.0074), with the pigs that received oral meloxicam having greater meloxicam plasma concentrations at 8 h compared with pigs that received a placebo patch or a patch containing meloxicam (P < 0.0001). There were no differences in plasma meloxicam concentrations between pigs receiving a placebo patch or a patch containing meloxicam (P = 0.9). Plasma levels of meloxicam were detectable but low in pigs that received a microneedle patch (0.91 ng/mL). Research is continuing to determine the ideal microneedle patch polymer and structure that would deliver meloxicam to achieve desired plasma concentrations.

Thin-Film Composite Membrane Compaction: Exploring the Interplay among Support Compressive Modulus, Structural Characteristics, and Overall Transport Efficiency.

Water scarcity has driven the demand for water production from unconventional sources and the reuse of industrial wastewater. Pressure-driven membranes, notably thin-film composite (TFC) membranes, stand as energy-efficient alternatives to the water scarcity challenge and various wastewater treatments. While pressure drives solvent movement, it concurrently triggers membrane compaction and flux deterioration. This necessitates a profound comprehension of the intricate interplay among compressive modulus, structural properties, and transport efficacy amid the compaction process. In this study, we present an all-encompassing compaction model for TFC membranes, applying authentic structural and mechanical variables, achieved by coupling viscoelasticity with Monte Carlo flux calculations based on the resistance-in-series model. Through validation against experimental data for multiple commercial membranes, we evaluated the influence of diverse physical parameters. We find that support polymers with a higher compressive modulus (lower compliance), supports with higher densities of "finger-like" pores, and "sponge-like" pores with optimum void fractions will be preferred to mitigate compaction. More importantly, we uncover a trade-off correlation between steady-state permeability and the modulus for identical support polymers displaying varying porosities. This model holds the potential as a valuable guide in shaping the design and optimization for further TFC applications and extending its utility to biological scaffolds and hydrogels with thin-film coatings in tissue engineering.

Mechanical Behavior of Polymer Braided Stent at Rapid Radial Loading

Stent implantation is the mainstream treatment for high-incidence vascular diseases. The stent is implanted into the blocked vessel with minimal trauma to restore blood flow. Polymer braided stents with superior biocompatibility and flexibility have broad application prospects in stent implantation. An ideal polymer stent should have suitable radial supporting capacity to withstand the cyclic radial load from vessels. Especially in the case of accelerated vasoconstriction caused by emotional excitement, drinking or fever, etc. However, there are currently limited studies on the mechanical properties of stent at rapid radial loading. In this work, the radial supporting capacity and fatigue properties of polymer stent at rapid loading rate were investigated by experiment and simulation. With the increase of radial loading rate, the stent has different deformation tendency and fatigue resistance. This study is helpful to study the structural changes of the polymer braided stent at different loading rates, and provide ideas for the evaluation and the optimization of the polymer braided stent.

Tailoring Hierarchical Structure and Rare Earth Affinity of Compositionally Identical Polymers via Sequence Control.

Macromolecule sequence, structure, and function are inherently intertwined. While well-established relationships exist in proteins, they are more challenging to define for synthetic polymer nanoparticles due to their molecular weight, sequence, and conformational dispersities. To explore the impact of sequence on nanoparticle structure, we synthesized a set of 16 compositionally identical, sequence-controlled polymers with distinct monomer patterning of dimethyl acrylamide and a bioinspired, structure-driving di(phenylalanine) acrylamide (FF). Sequence control was achieved through multiblock polymerizations, yielding unique ensembles of polymer sequences which were simulated by kinetic Monte Carlo simulations. Systematic analysis of the global (tertiary- and quaternary-like) structure in this amphiphilic copolymer series revealed the effect of multiple sequence descriptors: the number of domains, the hydropathy of terminal domains, and the patchiness (density) of FF within a domain, each of which impacted both chain collapse and the distribution of single- and multichain assemblies. Furthermore, both the conformational freedom of chain segments and local-scale, β-sheet-like interactions were sensitive to the patchiness of FF. To connect sequence, structure, and target function, we evaluated an additional series of nine sequence-controlled copolymers as sequestrants for rare earth elements (REEs) by incorporating a functional acrylic acid monomer into select polymer scaffolds. We identified key sequence variables that influence the binding affinity, capacity, and selectivity of the polymers for REEs. Collectively, these results highlight the potential of and boundaries of sequence control via multiblock polymerizations to drive primary sequence ensembles hierarchical structures, and ultimately the functionality of compositionally identical polymeric materials.

Development of hybrid electrospun alginate-pulverized moringa composites.

The consideration of biopolymers with natural products offers promising and effective materials with intrinsic and extrinsic properties that are utilized in several applications. Electrospinning is a method known for its unique and efficient performance in developing polymer-based nanofibers with tunable and diverse properties presented as good surface area, morphology, porosity, and fiber diameters during fabrication. In this work, we have developed an electrospun sodium alginate (SA) incorporated with pulverized Moringa oleifera seed powder (PMO) as a potential natural biosorbent material for water treatment applications. The developed fibers when observed using a scanning electron microscope (SEM), presented pure sodium alginate with smooth fiber (SAF) characteristics of an average diameter of about 515.09 nm (±114.33). Addition of pulverized Moringa oleifera at 0.5%, 2%, 4%, 6%, and 8% (w/w) reduces the fiber diameter to an average of about 240 nm with a few spindle-like pulverized Moringa oleifera particles beads of 300 nm (±77.97) 0.5% particle size and 110 nm (±32.19) with the clear observation of rougher spindle-like pulverized Moringa oleifera particle beads of 680 nm (±131.77) at 8% of alginate/Moringa oleifera fiber (AMF). The results from the rheology presented characteristic shear-thinning or pseudoplastic behaviour with a decline in viscosity, with characteristic behaviour as the shear rate increases, indicative of an ideal polymer solution suitable for the spinning process. Fourier transform infrared spectroscopy (FT-IR) shows the presence of amine and amide functional groups are prevalent on the alginate-impregnated moringa with water stability nanofibers and thermogravimetric analysis (TGA) with change in degradation properties in a clear indication and successful incorporation of the Moringa oleifera in the electrospun fiber. The key findings from this study position nanofibers as sustainable composites fiber for potential applications in water treatment, especifically heavy metal adsorption.

Crosslinker energy landscape effects on dynamic mechanical properties of ideal polymer hydrogels.

Reversible crosslinkers can enable several desirable mechanical properties, such as improved toughness and self-healing, when incorporated in polymer networks for bioengineering and structural applications. In this work, we performed coarse-grained molecular dynamics to investigate the effect of the energy landscape of reversible crosslinkers on the dynamic mechanical properties of crosslinked polymer network hydrogels. We report that, for an ideal network, the energy potential of the crosslinker interaction drives the viscosity of the network, where a stronger potential results in a higher viscosity. Additional topographical analyses reveal a mechanistic understanding of the structural rearrangement of the network as it deforms and indicate that as the number of defects increases in the network, the viscosity of the network increases. As an important validation for the relationship between the energy landscape of a crosslinker chemistry and the resulting dynamic mechanical properties of a crosslinked ideal network hydrogel, this work enhances our understanding of deformation mechanisms in polymer networks that cannot easily be revealed by experiment and reveals design ideas that can lead to better performance of the polymer network at the macroscale.

Optimization Process of the Pepsin-Solubilized Collagen from Lizardfish (Saurida tumbil Bloch, 1795) Skins by-Product

By-products from the marine fish processing are rich in organic compounds that can be converted into value-added products like collagen, and it is thought as an ideal candidate polymer for such research and medical applications. The lizardfish (Saurida tumbil Bloch, 1795) skin collagen had been investigated by our previous work, but an effective extraction method is needed to increase the yield of collagen. The purpose of this study was to optimize the method used to extract pepsin-solubilized collagen (PSC) from lizardfish skin. We employed an approach of one factor at a time (OFAT), along with response surface methodology (RSM) utilizing a central composite design (CCD), to attain the highest possible yield of the extracted collagen. Additionally, its properties were also assessed comparatively. The suggested optimal conditions for extraction were a pepsin concentration of 1.87%, a liquid-solid ratio of 24.90 mL/g, and a hydrolysis period of 38.09 h. Using these conditions resulted in a PSC yield of 21.82 g/100g, which closely matched the predicted collagen value.

Synthesis and Direct Observation of Molecules of 2D Polymers: With High Molecular Weights, Large Areas, Small Micropores, Solubility, Membrane Forming Ability, and High Oxygen Permselectivity.

If ideal 2D polymer (2DP) macromolecules with small pores that are similar in size to gas molecules, large areas, small thickness, and excellent membrane-forming ability are synthesized, ultimate gas separation membranes would be obtained. However, as far it is known, such ideal well-characterized 2DP macromolecules are not isolated. In this study, an ideal 2DP macromolecule is synthesized by using the successive three reactions (Glaser coupling, SCAT reaction, and the introduction of octyl groups), in which the conjugated framework structure is maintained, from a fully conjugated 1D polymer. Because this exfoliated 2DP is soluble, the macromolecular structure can be fully characterized by 1H-NMR, GPC, SEM, AFM, and its dense membrane with no defects can be fabricated by the solvent cast method. This soluble 2DP macromolecule has very small micropores (6.0Å) inside the macromolecule, a large area (30×68nm by SEM and AFM), high molecular weight (Mn=2.80×105 by GPC), and a small thickness (4.4Å by AFM). This membrane shows the highest oxygen permselectivity exceeding Robeson's upper line because of the high molecular sieving effect of the controlled small micropores.

Surface modification of aligned electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-based scaffold for binding with fibronectin or collagen in vascular tissue engineering

BackgroundVascular diseases are a leading cause of morbidity and mortality worldwide. The combination of the natural polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with essential extracellular matrix proteins such as fibronectin (FN) or collagen (COL) using various methods (coating, grafting and air plasma) to create small-diameter vascular grafts holds significant promise in the field of vascular tissue engineering. MethodsThe final data from this study indicated that after conjugation, the films maintained a smooth surface area and preserved morphology. Endothelial progenitor cells (EPCs) and human umbilical vein endothelial cells (HUVECs) were employed to assess the cytotoxicity, biocompatibility, and proliferation potential of cell lines treated with the synthesized films. The FN-binding PHBV and COL-binding PHBV films exhibited remarkable cell biocompatibility and cell proliferation rates. Furthermore, the treated cells exhibited specific gene expressions, including VEGFR-2, vWF, CD31, CD34, and CD133. Additionally, at specified time points, the cell retention rate and anti-coagulation ability of EPCs and HUVECs cultured on various PHBV films were tested, yielding successful outcomes. Significant findingsThe results suggested that FN-binding PHBV films represent an ideal bio-based polymer for applications in vascular tissue engineering.