Wormlike Polymer Research Articles

Bottlebrush Polyethylene Glycol Nanocarriers Translocate across Human Airway Epithelium via Molecular Architecture-Enhanced Endocytosis.

Pulmonary drug delivery is critical for the treatment of respiratory diseases. However, the human airway surface presents multiple barriers to efficient drug delivery. Here, we report a bottlebrush poly(ethylene glycol) (PEG-BB) nanocarrier that can translocate across all barriers within the human airway surface. Guided by a molecular theory, we design a PEG-BB molecule consisting of a linear backbone densely grafted by many (∼1000) low molecular weight (∼1000 g/mol) polyethylene glycol (PEG) chains; this results in a highly anisotropic, wormlike nanocarrier featuring a contour length of ∼250 nm, a cross-section of ∼20 nm, and a hydrodynamic diameter of ∼40 nm. Using the classic air-liquid-interface culture system to recapitulate essential biological features of the human airway surface, we show that PEG-BB rapidly penetrates through endogenous airway mucus and periciliary brush layer (mesh size of 20-40 nm) to be internalized by cells across the whole epithelium. By quantifying the cellular uptake of polymeric carriers of various molecular architectures and manipulating cell proliferation and endocytosis pathways, we show that the translocation of PEG-BB across the epithelium is driven by bottlebrush architecture-enhanced endocytosis. Our results demonstrate that large, wormlike bottlebrush PEG polymers, if properly designed, can be used as a carrier for pulmonary and mucosal drug delivery.

Selective Uptake Into Inflamed Human Intestinal Tissue and Immune Cell Targeting by Wormlike Polymer Micelles (Small 21/2024)

Selective Uptake Into Inflamed Human Intestinal Tissue and Immune Cell Targeting by Wormlike Polymer Micelles (Small 21/2024)

Skin-Friendly Flexible Ultraviolet Detectors Based on Reversibly Deformable Worm-Like Polymer Nanoparticles.

Flexible ultraviolet (UV) light detection technology has important applications in wearable devices, smart sensors, and other fields and attracts much attention in recent years. However, for most semiconductor-based UV detectors, the elastic modulus between rigid semiconductors and flexible substrates is mismatched, which makes it difficult to fabricate UV detectors that meet the needs of wearable devices. Herein, a fully flexible, large-scale, skin-friendly UV photodetector component centered on photo-responsive worm-like polymer nanoparticles (NPs) is developed, and the resulting device can quantitatively detect UV illumination. Skin-friendly poly(vinyl alcohol) (PVA), amphiphilic azobenzene-containing polymer NPs (AzNPs), and water-soluble ionic liquids (IL) are formed into (AzNPs-IL)/PVA fabrics by electrospinning. There are interactions such as hydrogen bonding among PVA, AzNPs, and IL, which make the material system stable. The UV detector made of the fabric realizes UV sensing through the illuminance-mechanical stress-electrical signal conversion mechanism. It is capable of achieving a response time of 9 s, a detection range of 10-150mW cm-2 , and stability for 1000 cycle tests upon 365nm UV irradiation. Moreover, it has good skin affinity, and the water contact angle of the fabric is only 23.57°, which holds great promise for wearable smart devices.

Selective Uptake Into Inflamed Human Intestinal Tissue and Immune Cell Targeting by Wormlike Polymer Micelles.

Inflammatory bowel disease (IBD)has become a globally prevalent chronic disease with no causal therapeutic options. Targeted drug delivery systems with selectivity for inflamed areas in the gastrointestinal tract promise to reduce severe drug-related side effects. By creating three distinct nanostructures (vesicles, spherical, and wormlike micelles) from the same amphiphilic block copolymer poly(butyl acrylate)-block-poly(ethylene oxide) (PBA-b-PEO), the effect of nanoparticle shape on human mucosal penetration is systematically identified. An Ussing chamber technique is established to perform the ex vivo experiments on human colonic biopsies, demonstrating that the shape of polymeric nanostructures represents a rarely addressed key to tissue selectivity required for efficient IBD treatment. Wormlike micelles specifically enter inflamed mucosa from patients with IBD, but no significant uptake is observed in healthy tissue. Spheres (≈25nm) and vesicles (≈120nm) enter either both normal and inflamed tissue types or do not penetrate any tissue. According to quantitative image analysis, the wormlike nanoparticles localize mainly within immune cells, facilitating specific targeting, which is crucial for further increasing the efficacy of IBD treatment. These findings therefore demonstrate the untapped potential of wormlike nanoparticles not only to selectively target the inflamed human mucosa, but also to target key pro-inflammatory cells.

Elastic traits of the extensible discrete wormlike chain model.

Polymer models play the special role of elucidating the elementary features describing the physics of long molecules and become essential to interpret the measurements of their magnitudes. In this work the end-to-end distance of an extensible discrete wormlike chain polymer as a function of the applied force has been calculated both numerically and analytically, the latter as an effective approximation. The numerical evaluation uses the transfer matrix formalism to obtain an exact calculation of the partition function, while the analytic derivations generalize the simple phenomenological formulas largely used up to now. The obtained formulas are simple enough to be implemented in the fit analysis of experimental data of semiflexible extensible polymers, with the result that the elastic parameters obtained are compatible with previous measurements, and more, their accuracy strongly improves in a large range of chain extensibility.

Non-Newtonian flows and instabilities in 3D glass microfluidic devices

<h2>Abstract</h2> In this virtual seminar we will discuss the use of selective laser-induced etching (SLE) for the fabrication of glass microfluidic devices, in particular for the study of non-Newtonian fluid dynamics problems [1]. SLE enables the precise monolithic fabrication of three-dimensional (3D) channels and structures embedded in a rigid and transparent fused-silica substrate, and thus provides opportunities for a wealth of novel microscale flow experiments. We will highlight various recent and ongoing microfluidic projects from our laboratory that have been made possible by SLE fabrication. Our focus will be on flows of viscoelastic wormlike micellar and polymer solutions in microscale geometries featuring, for instance, slender rigid or cantilevered posts [2,3]. 3D intersections [4,5], and axisymmetric contraction/expansions [6]. We make use of state-of-the-art quantitative techniques such as high-speed flow-induced birefringence imaging and volumetric 3-component micro-particle image velocimetry to characterize and understand purely-elastic and inertioelastic flow instabilities arising in these complex systems.

Molecularly Imprinted Electrochemical Sensor Based on 3D Wormlike PEDOT-PPy Polymer for the Sensitive Determination of Rutin in Flos Sophorae Immaturus

A molecularly imprinted polymer (MIP) with 3D worm-like nanorod structures was constructed by cyclic voltammetry (CV) polymerization, using 3,4-ethylenedioxythiophene (EDOT) and pyrrole (Py) as bifunctional monomers, and rutin as the template on a glassy carbon electrode (GCE). The optimum polymerization conditions of MIP were obtained by the orthogonal test. The range analysis suggested that the potential range was the most influential factor. Compared with MIP/1.5 and MIP/1.9, the MIP films prepared in the potential range of 0–1.7 V (MIP/1.7) had better current response to rutin, faster charge transfer rate and higher doping levels by differential pulse voltammetry (DPV), Chronocoulometry and X-ray photoelectron spectroscopy (XPS) analysis. Rutin could be detected in the concentration range of 0.5 nM to 1 μM, and 5 to 50 μM with the low detection limit as 0.24 nM (S/N = 3). Moreover, MIP/1.7 exhibited 3-fold increase current response toward rutin by DPV when compared with the corresponding non-imprinted polymer (NIP), revealing the success of the imprinting. This sensor also exhibited high selectivity, good long-term stability, and acceptable reproducibility. The rutin content in Flos Sophorae Immaturus (FSI) was 25.37% with good accuracy.

Nematic ordering of worm-like polymers near an interface.

The phase behavior of semi-flexible polymers is integral to various contexts, from materials science to biophysics, many of which utilize or require specific confinement geometries as well as the orientational behavior of the polymers. Inspired by collagen assembly, we study the orientational ordering of semi-flexible polymers, modeled as Maier-Saupe worm-like chains, using self-consistent field theory. We first examine the bulk behavior of these polymers, locating the isotropic-nematic transition and delineating the limit of stability of the isotropic and nematic phases. This effort explains how nematic ordering emerges from the isotropic phase and offers insight into how different (e.g., mono-domain vs multi-domain) nematic phases form. We then clarify the influence of planar confinement on the nematic ordering of the polymers. We find that while the presence of a single confining wall does not shift the location of nematic transition, it aligns the polymers in parallel to the wall; above the onset of nematic transition, this preference tends to propagate into the bulk phase. Introducing a second, perpendicular, wall leads to a nematic phase that is parallel to both walls, allowing the ordering direction to be uniquely set by the geometry of the experimental setup. The advantage of wall-confinement is that it can be used to propagate mono-domain nematic phases into the bulk phase.

Numerical Simulation of the Distribution Function and Free Energy of a Single Wormlike Polymer Confined between Hard Walls

We focus on the distribution and free energy of a wormlike polymer confined between two parallel hard walls. The variation in the distribution and free energy of the wormlike chain as the spacing between the walls decreases (or as the total contour length of the wormlike chain increases or as the persistence length of the chain increases) is simulated. The main reason for these changes is a degradation of the long wormlike chain into a Gaussian long chain under weak confinement.

A Pore Scale Study of Non-Newtonian Effect on Foam Propagation in Porous Media

CO2 injection is one of the most promising techniques to enhance oil recovery. However, an unfavorable mobility ratio, reservoir heterogeneity and gravity segregation can reduce the macroscopic sweep efficiency. In situ foaming of injected CO2 is the method that has the most potential for improving sweep efficiency based on controlling CO2 mobility. This study investigates the foaming behavior of N,N,N′-trimethyl-N′-tallow-1,3-diaminopropane (DTTM) surfactant with CO2 in a transparent porous microflow model with natural rock pore structures. It focuses on the effect of the salinity induced non-Newtonian behavior of DTTM solution on foam propagation. The performance of foams stabilized by 0.5 wt% DTTM solution over the viscosity range from 0.71 (at 5 wt% NaCl) to 41 cp (at 20 wt% NaCl) was compared with conventional polymer-enhanced foams whose liquid phase contained a commonly used foaming surfactant, C15–18 Internal Olefin Sulfonate (C15–18 IOS) and a hydrolyzed polyacrylamide. Such comparisons have also provided insight into the respective impacts of liquid phase viscosification by worm-like surfactant micelles and polymer on foam texture associated with its rheological characteristics. It was found that at low aqueous phase viscosity (injection liquid viscosity of 0.71 cp) the maximum achievable viscosity of DDTM foam was around 1000 cp, which was 80 times IOS stabilized foam. The interfacial tension of DTTM was higher than that of IOS, resulting coarser foam texture and higher individual lamella resistance. An increase in DTTM solution viscosity by a factor of 33 decreased foam generation and viscosity for gas injection. This was not observed for the simultaneous injection of gas and DTTM solution. Overall, the effect of liquid phase viscosity on transient foam behavior during gas injection is similar for both DTTM and IOS regardless of the difference in the nature of viscosifying agents (WLM vs 3330 s polymer). An increase in gas injection pressure without liquid injection delayed foam propagation and reduced the magnitude of foam viscosity. The results from this study indicated that DTTM surfactant is an important alternative to commercially available polymers that have been used to enhance foam performance in porous media. This particular surfactant type also overcomes several disadvantages of polymers such as limited temperature and salinity tolerance, shear degradation, and filtering in low permeability formations.

Predictions for circular contraction-expansion flows with viscoelastoplastic & thixotropic fluids

In this predominately predictive modelling finite volume/element study, a comparative analysis is performed for time-dependent and viscoelastoplastic flow in a circular contraction-expansion geometry of aspect-ratio 10:1:10. For this, a hybrid finite volume/element scheme is employed. A new and revised micellar model is investigated, under the denomination of BMP+_τp, which reflects a bounded extensional viscosity response and an N1Shear-upturn at large deformation rates (lost in earlier model-variants), a versatile model capable of supporting plasticity, shear-thinning, strain softening-hardening and shear-banding. Many of these features are common to wormlike micellar and polymer solutions. Then, findings are contrasted against a de Souza Mendes model. Two flow regimes are addressed: plastic flow (low flow-rate Q ≤ 1 units, solvent-fraction β < 10−1) and viscoelastic flow (larger-Q > 1; minimised plasticity; β = 1/9); as quantified via flow-structure, yield-fronts and pressure-drops. Under the plastic regime, elasticity-increase causes asymmetry about the contraction-plane, whilst yield-stress and enhanced strain-hardening promote solid-like features, apparent through augmented unyielded-regions and rising pressure-drops. Concerning the viscoelastic regime and vortex-structures, extensional-deformation experienced correlates with hardening expectation in uniaxial-extension, whilst streamline activity in vortex-cells correlates with normal-stress response in shear. Adjustment in strain-hardening/softening response with Q-rise, provides translation from weaker salient-corner vortex centres to stronger elastic corner-vortices; yet, when softening finally prevails, asymmetric upstream/downstream salient-corners vortex patterns are recovered. For strong-hardening and solvent-dominated β∼0.8 fluids (as with Boger fluids), an intermediate lip-vortex-formation phase is noted, alongside coexistence of salient-corner vortices. Such a vortex-coexistence phase is distinctly absent in solute-concentrated fluids.

Characterisation of flexible fibre deformations in turbulence

The transport of deformable objects by a turbulent flow is common in environmental sciences which are interested, for instance, in the dynamics of plankton in the ocean, and in industry, such as the papermaking or textile industries. In this study, the deformations of flexible fibres in homogeneous isotropic turbulence are experimentally and numerically investigated, focusing on the local curvature κ. By comparing our results to the predictions for worm-like chain polymers in an ideal solvent, we are able to identify the role of the spatial and temporal correlations of the turbulent forcing. In particular, we show that these correlations are responsible for a straightening of long fibres which become statistically less distorted by turbulence as their length increases.

General Syntheses of Nanotubes Induced by Block Copolymer Self-Assembly.

Amphiphilic block copolymer templating strategies are extensively used for syntheses of mesoporous materials. However, monodisperse tubular nanostructures are limited. Here, a general method is developed to synthesize monodisperse nanotubes with narrow diameter distribution induced by self-assembly of block copolymer. 3-Aminophenol (AP) and formaldehyde (F) polymerize and self-assemble with cylindrical PS-b-PEO micelles into worm-like PS-b-PEO@APF composites with uniform diameter (49 ± 3 nm). After template extraction, worm-like APF polymer nanotubes are formed. The structure and morphology of the polymer nanotubes can be tuned by regulating the synthesis conditions. Furthermore, PS-b-PEO@APF composites are uniformly converted to isomorphic carbon nanotubes with large surface area of 662 m2 g-1 , abundant hierarchical porous frameworks and nitrogen doping. The synthesis can be extended to silica nanotubes. These findings open an avenue to the design of porous materials with controlled structural framework, composition, and properties for a wide range of applications.

Enzyme-PISA: An Efficient Method for Preparing Well-Defined Polymer Nano-Objects under Mild Conditions.

Enzyme catalysis is a mild, efficient, and selective technique that has many applications in organic synthesis as well as polymer synthesis. Here, a novel enzyme-catalysis-induced reversible addition-fragmentation chain transfer (RAFT)-mediated dispersion polymerization for preparing AB diblock copolymer nano-objects with complex morphologies at room temperature is described. Taking advantage of the room-temperature feature, it is shown that pure, worm-like polymer nano-objects can be readily prepared by just monitoring the viscosity. Moreover, it is demonstrated that inorganic nanoparticles and proteins can be loaded in situ into vesicles by this method. Finally, a novel oxygen-tolerant RAFT-mediated dispersion polymerization initiated by enzyme cascade reaction that can be carried out in open vessels is developed. The enzyme-initiated RAFT dispersion polymerization provides a facile platform for the synthesis of various functional polymer nano-objects under mild conditions.

Polymer growth spurts revealed

When chemists think about polymerization, they typically envision a wormlike polymer growing smoothly and continuously from a catalyst. But the actual view of how polymer growth unfolds has remained murky because of the limitations of analytical techniques. Using a pair of magnetic tweezers, optical microscopy, and spectroscopic techniques, Cornell University researchers led by Peng Chen, Geoffrey W. Coates, and Fernando A. Escobedo have achieved the first real-time visualization of single polymer chain growth. What they report is startling: Individual polymer chains don’t increase steadily but instead undergo consecutive wait and jump steps. With the aid of molecular dynamics computer simulations, the researchers attribute this jerky mechanism to formation of polymer tangles—which they call hair balls—that form around the catalyst as thousands of new monomer units are added to the growing chain. The hair balls sporadically unravel after a couple of minutes, and a new hair ball starts to form. Besides

Analytical expressions for the closure probability of a stiff wormlike chain for finite capture radius.

Estimating the probability that two monomers of the same polymer chain are close together is a key ingredient to characterize intramolecular reactions and polymer looping. In the case of stiff wormlike polymers (rigid fluctuating elastic rods), for which end-to-end encounters are rare events, we derive an explicit analytical formula for the probability η(r_{c}) that the distance between the chain extremities is smaller than some capture radius r_{c}. The formula is asymptotically exact in the limit of stiff chains, and it leads to the identification of two distinct scaling regimes for the closure factor, originating from a strong variation of the fluctuations of the chain orientation at closure. Our theory is compatible with existing analytical results from the literature that cover the cases of a vanishing capture radius and of nearly fully extended chains.

Thermodynamics of a Compressible Maier-Saupe Model Based on the Self-Consistent Field Theory of Wormlike Polymer.

This paper presents a theoretical formalism for describing systems of semiflexible polymers, which can have density variations due to finite compressibility and exhibit an isotropic-nematic transition. The molecular architecture of the semiflexible polymers is described by a continuum wormlike-chain model. The non-bonded interactions are described through a functional of two collective variables, the local density and local segmental orientation tensor. In particular, the functional depends quadratically on local density-variations and includes a Maier–Saupe-type term to deal with the orientational ordering. The specified density-dependence stems from a free energy expansion, where the free energy of an isotropic and homogeneous homopolymer melt at some fixed density serves as a reference state. Using this framework, a self-consistent field theory is developed, which produces a Helmholtz free energy that can be used for the calculation of the thermodynamics of the system. The thermodynamic properties are analysed as functions of the compressibility of the model, for values of the compressibility realizable in mesoscopic simulations with soft interactions and in actual polymeric materials.

The influence of fiber on the rheological properties, microstructure and suspension behavior of the supramolecular viscoelastic fracturing fluid

An innovative fiber-based fracturing fluid technology has been developed to enhance the productivity of low-permeability and ultra-low-permeability reservoirs. However, few studies have focused on the influence of fiber on the rheological properties, microstructure and suspension behavior of a supramolecular fracturing fluid. In this article, the rheological properties, microstructure and proppant suspension behavior of the supramolecular fluid affected by the fibers were discussed. The rheological measurement showed the addition of fibers facilitated the formation of the fiber network and strengthened the mechanical network structure which improved the rheological properties of the fluid. The addition of fibers did not change the reversible shear thinning behavior of this fluid. Meanwhile, it was proven that the power-law model could accurately predict the rheological parameters of this fiber-laden fracturing fluid. Both temperature and shear rate could disassemble the complex structure of this fiber-based fracturing fluid resulting in the decrease of viscosity. The scanning electron microscopes (SEM) micrographs demonstrated the supramolecular network honeycomb structure of the fluid, which was made up of the wormlike micelles and polymer chains with extremely efficient physical crosslinking. The proppant suspension data indicated the elasticity factor did not represent the proppant suspension capacity of the liquid. The results of the rheological measurement, SEM and the static-column test showed that the fiber network could improve the proppant suspension capacity through strengthening the ability of load bearing and consolidation of the fluid.

Theory for nonlinear dynamic force spectroscopy

Dynamic force spectroscopy (DFS) is an experimental technique that is commonly used to assess information on the strength, energy landscape, and lifetime of noncovalent bio-molecular interactions. DFS traditionally requires an applied force that increases linearly with time so that the bio-complex under investigation is exposed to a constant loading rate. However, tethers or polymers can modulate the applied force in a nonlinear manner. For example, bacterial adhesion pili and polymers with worm-like chain properties are structures that show nonlinear force responses. In these situations, the theory for traditional DFS cannot be readily applied. In this work, we expand the theory for DFS to also include nonlinear external forces while still maintaining compatibility with the linear DFS theory. To validate the theory, we modeled a bio-complex expressed on a stiff, an elastic, and a worm-like chain polymer, using Monte Carlo methods, and assessed the corresponding rupture force spectra. It was found that the nonlinear DFS (NLDFS) theory correctly predicted the numerical results. We also present a protocol suggesting an experimental approach and analysis method of the data to estimate the bond length and the thermal off-rate.

Nematic ordering of semiflexible polymers confined on a toroidal surface.

We study the isotropic-like and nematic states of wormlike liquid-crystal polymers embedded on the surface of a torus. The role played by surface curvature, which couples to the molecular rigidity, is reported as the main reason that causes the weak nematic ordering in an otherwise ordinary isotropic phase. The same coupling has a profound effect on the nematic states as well, which are stabilized by the Onsager excluded-volume interaction; the latter has been frequently used to study lyotropic liquid crystal polymers and is used here as an example of the physical mechanisms that drive the system to make orientational ordering. We identify important parameters in the system which are used as axes of the four-dimensional phase diagram. The numerical study demonstrates a strong correlation between the liquid-crystal defect-free and defect structures and the geometry of the liquid-crystal embedded surface.