Elastic Polymer Research Articles

Comparative evaluation of the effectiveness of prosthodontic treatment using the original immediate denture design and traditional methods

BACKGROUND: Patients with chronic non-correctable periodontal disease, leading to loss of teeth, can be rehabilitated using immediate dentures. However, removable dentures often produce excessive mechanical pressure on the underlying prosthetic bed tissues.
 AIM: To evaluate the effectiveness of various options for immediate dentures and their effects on the rate of wound healing in patients with a complete absence of teeth due to surgical removal for chronic periodontitis.
 MATERIALS AND METHODS: Early prosthodontics treatment was conducted on 30 patients after extracting multiple teeth at the Department of Orthopedic Dentistry and Orthodontics of the Ryazan State Medical University. The patients were divided into 3 groups depending on the options for immediate dentures: 1) combined construction of acrylic, non-monomer and elastic polymer, 2) hot curing acrylic polymer, and 3) thermoplastic plastic. Treatment effectiveness was measured by the objective state of the wound area with a planimetric assessment of wound healing. Pain sensitivity when using the prosthesis was rated according to a numeric rating scale for pain. The stability of prostheses was assessed according to the Mirgazizov method, an assessment of the safety of the drug based on the prosthesis. Diagnostic observations were carried out for 21 days.
 RESULTS: Postoperative rehabilitation was faster in groups 1 and 3, than in group 2. By day 21, inflammation persisted only in group 2, which was confirmed by the largest wound size (8.31.1 mm) compared with that of groups 1 (5.11.9 mm) and 3 (6.32.4 mm). Complaints of pain during the use of prostheses were noted in half of the patients in groups 2 and 3, whereas only slight discomfort persisted in 3 patients in group 1. The stability of the prostheses deteriorated in group 3 by day 21 (5.91.4 points), indicating lower adaptability of thermoplastic prostheses to changes in the relief of the prosthetic bed than with the combined construction (6.71.4 points). The acrylic prostheses demonstrated the lowest adaptability (3.21 points). The indicator of daily preservation of drugs under the bases of dentures in group 1 patients was 36.82 mm2, that in patients of group 3 was 30.31.8 mm2, and that in patients of group 2 was the lowest at 24.41.4 mm2.
 CONCLUSION: The principle of combining polymeric materials to create immediate dentures was the method of choice for prosthodontics treatment of patients with a complete absence of teeth due to surgical removal, as this category of patients is most sensitive to inflammatory complications during the postoperative period.

Single-Chain Inherent Elasticity of Macromolecules: From Concept to Applications.

"The Tao begets the One. One begets all things of the world." These words of wisdom from Tao Te Ching are of great inspiration to scientists in polymer materials science and engineering: The "One" means an individual polymer chain while polymer materials consist of numerous chains. The understanding of the single-chain mechanics of polymers is crucial for the bottom-up rational design of polymer materials. With a backbone and side chains, a polymer chain is more complex than a small molecule. Moreover, an individual polymer chain is usually placed in a complicated environment (such as solvent, cosolute, and solid surface), which significantly affects the behaviors of the chain. With all these factors, it is hard to fully understand the elastic behaviors of polymers. Herein, we will first introduce the concept of the single-chain inherent elasticity of polymers, which is a fundamental property determined by the polymer backbone. Then, the applications of inherent elasticity in quantifying the effects of side chains and surrounding environment will be summarized. Finally, the challenges in related fields at present and potential research directions in the future will be discussed.

Magnetically Tunable One-Dimensional Plasmonic Photonic Crystals.

Integrating plasmonic resonance into photonic bandgap nanostructures promises additional control over their optical properties. Here, one-dimensional (1D) plasmonic photonic crystals with angular-dependent structural colors are fabricated by assembling magnetoplasmonic colloidal nanoparticles under an external magnetic field. Unlike conventional 1D photonic crystals, the assembled 1D periodic structures show angular-dependent colors based on the selective activation of optical diffraction and plasmonic scattering. They can be further fixed in an elastic polymer matrix to produce a photonic film with angular-dependent and mechanically tunable optical properties. The magnetic assembly enables precise control over the orientation of the 1D assemblies within the polymer matrix, producing photonic films with designed patterns displaying versatile colors from the dominant backward optical diffraction and forward plasmonic scattering. The combination of optical diffraction and plasmonic properties within a single system holds the potential for developing programmable optical functionalities for applications in various optical devices, color displays, and information encryption systems.

Mapping the geometry dependent relative stress in stretched polymer membranes by polarization and interferometric techniques

This paper reports experimental results on contactless geometry dependent stress characterisation and mapping in elastic polymer membranes using polarization and interferometric techniques. Three different geometries of polydimethylsiloxane (PDMS) namely, rectangular, wedge and bowtie shaped membranes are studied. The membranes were initially stretched and then relaxed from one edge during the characterisation. In the rectangular membrane the stress was observed to be concentrated at the static edge of the membrane. Whereas, in the wedge and bowtie shaped membranes, the stress is found to be concentrated at the locations wherein the membrane has a narrower width. The proposed facile methods for characterisation are helpful in designing stress induced tuneable optics and to analyze stress in polymer membranes during their industrial production.

Tailoring Enhanced Elasticity of Crystalline Coordination Polymers.

The approach for enhancing the elasticity of crystals with suboptimal elastic performances through a rational design was presented. A hydrogen-bonding link was identified as a critical feature in the structure of the parent material, the Cd(II) coordination polymer [CdI2(I-pz)2] n (I-pz = iodopyrazine), to determine the mechanical output and was modified via cocrystallization. Small organic coformers resembling the initial organic ligand but with readily available hydrogens were selected to improve the identified link, and the extent of strengthening the critical link was in an excellent correlation with the delivered enhancement of elastic flexibility materials.

A preclinical platform for assessing long-term drug efficacy exploiting mechanically tunable scaffolds colonized by a three-dimensional tumor microenvironment

BackgroundLong-term drug evaluation heavily relies upon rodent models. Drug discovery methods to reduce animal models in oncology may include three-dimensional (3D) cellular systems that take into account tumor microenvironment (TME) cell types and biomechanical properties.MethodsIn this study we reconstructed a 3D tumor using an elastic polymer (acrylate-endcapped urethane-based poly(ethylene glycol) (AUPPEG)) with clinical relevant stiffness. Single cell suspensions from low-grade serous ovarian cancer (LGSOC) patient-derived early passage cultures of cancer cells and cancer-associated fibroblasts (CAF) embedded in a collagen gel were introduced to the AUPPEG scaffold. After self-organization in to a 3D tumor, this model was evaluated by a long-term (> 40 days) exposure to a drug combination of MEK and HSP90 inhibitors. The drug-response results from this long-term in vitro model are compared with drug responses in an orthotopic LGSOC xenograft mouse model.ResultsThe in vitro 3D scaffold LGSOC model mimics the growth ratio and spatial organization of the LGSOC. The AUPPEG scaffold approach allows to test new targeted treatments and monitor long-term drug responses. The results correlate with those of the orthotopic LGSOC xenograft mouse model.ConclusionsThe mechanically-tunable scaffolds colonized by a three-dimensional LGSOC allow long-term drug evaluation and can be considered as a valid alternative to reduce, replace and refine animal models in drug discovery.Graphical

Fabrication of PLCL Block Polymer with Tunable Structure and Properties for Biomedical Application.

Biodegradable materials are pivotal in the biomedical field, where how to precisely control their structure and performance is critical for their translational application. In this study, poly(L-lactide-b-ε-caprolactone) block copolymers (bPLCL) with well-defined segment structure are obtained by a first synthesis of poly(ε-caprolactone)soft block, followed by ring opening polymerization of lactide to form poly(L-lactideacid) hard block. The pre-polymerization allows for fabrication of bPLCL with the definite compositions of soft/hard segment while preserving the individual segment of their special soft or hard segment. These priorities make the bPLCL afford biodegradable polymer with better mechanical and biodegradable controllability than the random poly(L-lactide-co-ε-caprolactone) (rPLCL) synthesized via traditional one-pot polymerization. 10 mol% ε-caprolactone introduction can result in a formation of an elastic polymer with elongation at break of 286.15% ± 55.23%. Also, bPLCL preserves the unique crystalline structure of the soft andhard segments to present a more sustainable biodegradability than the rPLCL. The combinative merits make the pre-polymerization technique a promising strategy for a scalable production of PLCL materials for potential biomedical application.

A Review of Flexible Strain Sensors Based on Natural Fiber Materials

AbstractFlexible strain sensors with outstanding stretchability and sensitivity can be widely used in medical health, smart robot, intelligent garment, man‐machine interaction, and other fields. The use of natural fibers enables a green manufacturing pathway to design strain sensors within the context of increasingly serious environmental pollution. Commercialized natural fibers, including cellulose fibers (cotton and fibrilia), protein fibers (wool and silk), and their regenerated materials (viscose and silk fibroin) exhibit low cost, easy acquisition, and degradability as the basis materials. This paper reviews the preparation methods, performances, and applications of flexible strain sensors based on these natural fibers. Cellulose and protein fibers are carbonized or coated with conductive nanomaterials to form the strain sensing network, and then, elastic polymers are used to improve the sensor strain range. Regenerated natural fiber materials can be uniformly mixed with conductive materials to form conductive composites for sensors. The strain‐sensing performances and mechanisms are analyzed and compared. Natural fiber‐based strain sensors are studied to pave the way for practical integration in electronic systems.

Theory of low-temperature elasticity of amorphous polymers: Deformation at a constant rate and relaxation of deforming stress

The effect of temperature variations over a wide range on the rheological properties of amorphous polymers with high rubber-like elasticity (elastomers) is discussed. A theoretical study of the transition from the deformation state of a warm elastomer to the state of a frozen one, the effects of structural-strain glass transition and forced elasticity was done. Two types of mechanical testing of polymer samples are considered in detail: slow tensile deformation at a constant rate and relaxation of the deforming stress after deformation stops. The study was carried out on the basis of the previously proposed molecular-kinetic model of the processes of highly elastic deformation of amorphous polymers and the corresponding nonlinear rheological equation (V. D. Natsik and H. V. Rusakova, Fiz. Nizk. Temp. 48, 281 (2022) [Low Temp. Phys. 48, 253 (2022)]).

Phosphorescent extensophores expose elastic nonuniformity in polymer networks

Networks and gels are soft elastic solids of tremendous technological importance that consist of cross-linked polymers whose structure and connectivity at the molecular level are fundamentally nonuniform. Pre-failure local mechanical responses are not understood at the level of individual crosslinks, despite the enormous attention given to their macroscopic mechanical responses and to developing optical probes to detect their loci of mechanical failure. Here, introducing the extensophore concept to measure nondestructive forces using an optical probe with continuous force readout proportional to deformation, we show that the crosslinks in an elastic polymer network extend, fluctuate, and deform with a wide range of molecular individuality. Requiring little specialized equipment, this foundational single-molecule phosphorescence approach, applied here to polymer science and engineering, can be useful to a broad science and engineering community.

Unfolding/refolding of single polyproteins held under constant tension: Effect of monovalent salts on folding/unfolding rates

Protein elasticity is a fundamental physical characteristic and, in some cases, a key functional property of proteins. Many proteins consist of tandem repeats of identical or similar domains and display an elasticity that is dependent on the folding/unfolding of their individual domains. These proteins allow for extreme extensions beyond their resting length with distinct, stepped increases/decreases in length when held under ramped or constant tensions. Here we present the extension of a poly-protein consisting of 8 tandem repeats of Protein L held under constant tension utilizing a magnetic tweezers technique. We present a model of the observed results employing a simple two-state model for the unfolding of each domain. The model includes the polymer elasticity of the entire chain and incorporates the indistinguishability of the Protein L domains. From this model, we have estimated the change in energy for the unfolding of a single Protein L as 6.5 kT. Further, we explored the dependency of folding/unfolding rates under tension on environmental salt concentration. We have found that increases in NaCl concentration tend to increase the transition rates between states of unfolding without much perturbation to the probability of being in a given unfolded state, implying a lowering of the barrier to protein folding/unfolding in protein L due to excess environmental salts.

Soft Optomechanical Systems for Sensing, Modulation, and Actuation

AbstractSoft optomechanical systems have the ability to reversibly respond to optical and mechanical external stimuli by changing their own properties (e.g., shape, size, viscosity, stiffness, color or transmittance). These systems typically combine the optical properties of plasmonic, dielectric or carbon‐based nanomaterials with the high elasticity and deformability of soft polymers, thus opening the path for the development of new mechanically tunable optical systems, sensors, and actuators for a wide range of applications. This review focuses on the recent progresses in soft optomechanical systems, which are here classified according to their applications and mechanisms of optomechanical response. The first part summarizes the soft optomechanical systems for mechanical sensing and optical modulation based on the variation of their optical response under external mechanical stimuli, thereby inducing mechanochromic or intensity modulation effects. The second part describes the soft optomechanical systems for the development of light induced mechanical actuators based on different actuation mechanisms, such as photothermal effects and phase transitions, among others. The final section provides a critical analysis of the main limitations of current soft optomechanical systems and the progress that is required for future devices.

3D printing shape memory polymer of laminated multi-component metamaterial towards optimization of auxetic and shape recovery behaviors

With the development of multifunctional metamaterials, auxetic shape memory metamaterials have attracted extensive attentions. However, the combination of material property into structural metamaterial has not been fully understand. In this study, a 3D printing laminated multi-component metamaterial has been manufactured using the viscoelastic and elastic shape memory polymers (SMPs), to achieve a tailorable release rate of strain energy for optimization of auxetic and shape recovery behaviors. A synergistic effect of laminated structure arrangement and cell radius has been identified as the driving force to achieve the auxetic behavior (for metamaterial), high storage strain energy (for yielding strength) and release rate (for shape recovery behavior). Finally, the auxetic, yielding, and shape recovery behaviors have been experimentally tested, to verify the effectiveness of the finite element method results. And a good agreement between them has been achieved. This study is expected to provide a design guideline for auxetic and shape recovery behaviors of laminated multi-component SMP metamaterial.

Photo‐Patternable Stretchable Semi‐Interpenetrating Polymer Semiconductor Network Using Thiol–Ene Chemistry for Field‐Effect Transistors

AbstractStretchable polymer semiconductors are an essential component for skin‐inspired electronics. However, the lack of scalable patterning capability of stretchable polymer semiconductors limits the development of stretchable electronics. To address this issue, photo‐curable stretchable polymer blends consisting of a high‐mobility donor–acceptor conjugated polymer and an elastic rubber through thiol–ene chemistry are developed. The thiol–ene reaction can selectively cross‐link the rubber with alkene or vinyl groups without damaging the electronic properties of the conjugated polymer. The conjugated polymer chains embedded in the elastic polymer matrix induce a semi‐interpenetrating polymer network (SIPN). The thiol–ene‐cross‐linked network provides great solvent resistance and enhances stretchability for the embedded conjugated polymer. The well‐defined patterned film with a feature size of ≈10 µm can be obtained using UV light at 365 nm through conventional photolithography processes. Furthermore, the SIPN‐based transistors show increased mobilities from 0.61 to 1.18 cm2 V−1 s−1 when applying the strain from 0% to 100%. Moreover, the hole mobility can still maintain at 0.87 cm2 V−1 s−1 after 1000 strain‐and‐release cycles at the strain of 25%. This study sheds light on the molecular design of photo‐curable polymer semiconductors for the mass production of stretchable circuits.

Robust Neural Interfaces with Photopatternable, Bioadhesive, and Highly Conductive Hydrogels for Stable Chronic Neuromodulation.

A robust neural interface with intimate electrical coupling between neural electrodes and neural tissues is critical for stable chronic neuromodulation. The development of bioadhesive hydrogel neural electrodes is a potential approach for tightly fixing the neural electrodes on the epineurium surface to construct a robust neural interface. Herein, we construct a photopatternable, antifouling, conductive (∼6 S cm-1), bioadhesive (interfacial toughness ∼100 J m-2), soft, and elastic (∼290% strain, Young's modulus of 7.25 kPa) hydrogel to establish a robust neural interface for bioelectronics. The UV-sensitive zwitterionic monomer can facilitate the formation of an electrostatic-assembled conductive polymer PEDOT:PSS network, and it can be further photo-cross-linked into elastic polymer network. Such a semi-interpenetrating network endows the hydrogel electrodes with good conductivity. Especially, the photopatternable feature enables the facile microfabrication processes of multifunctional hydrogel (MH) interface with a characteristic size of 50 μm. The MH neural electrodes, which show improved performance of impedance, charge storage capacity, and charge injection capability, can produce effective electrical stimulation with high current density (1 mA cm-2) at ultralow voltages (±25 mV). The MH interface could realize high-efficient electrical communication at the chronic neural interface for stable recording and stimulation of a sciatic nerve in the rat model.

Stretchable and biodegradable chitosan-polyurethane-cellulose nanofiber composites as anisotropic materials

Chitosan is a naturally derived biodegradable polymer with abundancy, sustainability, and ease of chemical modification. Polyurethanes are a family of elastic biocompatible polymers, and composites of polyurethanes have versatile properties and applications. Chitosan-polyurethane composites were recently developed but had insufficient strength and limited stretchability. In the current study, cellulose nanofibers (CNFs) were integrated in chitosan-polyurethane composites to prepare stretchable and anisotropic materials. A biodegradable polyurethane was first synthesized, end-capped with aldehyde to become dialdehyde polyurethane (DP) nanoparticles, and added with CNFs to prepare the DP-CNF composite crosslinker (DPF). The waterborne DPF crosslinker was then blended with chitosan solution to make polyurethane-CNF-chitosan (DPFC) composites. After blending, DPFC may form hydrogel in ~33 min at room temperature, which confirmed crosslinking. Composite films cast and dried from the blends showed good elongation (~420.2 %) at 60 °C. Anisotropic films were then generated by tension annealing with pre-strain. The annealed films with 200 % pre-strain exhibited large elastic anisotropy with ~4.9 anisotropic ratio. In situ SAXS/WAXS analyses unveiled that rearrangement and alignment of the microstructure during tension annealing accounted for the anisotropy. The anisotropic composite films had the ability to orient the growth of neural stem cells and showed the potential for biomimetic and tissue engineering applications.

Highly Elastic hyperbranched polymer binder for silicon anodes in lithium-ion batteries

With extremely high theoretical capacity, silicon (Si) has been considered as one of the most promising anode materials for next-generation lithium ion batteries (LIBs). However, Si electrodes undergo huge volume changes and pulverization during the actual charge-discharge processes. In response, polymer binders can bind Si particles together, preventing the electrodes from decomposition during operation. On this basis, a novel Si-anodic elastic polymer binder system based on cross-linked hyperbranched polyethyleneimine (HPEI) with optimized cross-linker length was developed, which could achieve a good balance between the mechanical elasticity and bonding reversibility of the network. The as-prepared Si anode exhibits a high discharge capacity of 2630 mAh g−1 at a current density of 500 mA g−1, and maintains excellent cycling stability with a high capacity retention of 78.7% after 200 cycles at a high current rate of 2000 mA g−1.

Establishment of Unstable Flow Model and Well Testing Analysis for Viscoelastic Polymer Flooding

At present, the polymer solution is usually assumed to be Newtonian fluid or pseudoplastic fluid, and its elasticity is not considered on the study of polymer flooding well testing model. A large number of experiments have shown that polymer solutions have viscoelasticity, and disregarding the elasticity will cause certain errors in the analysis of polymer solution seepage law. Based on the percolation theory, this paper describes the polymer flooding mechanism from the two aspects of viscous effect and elastic effect, the mathematical model of oil water two-phase three components unsteady flow in viscoelastic polymer flooding was established, and solved by finite difference method, and the well-test curve was drawn to analyze the rule of well test curve in polymer flooding. The results show that, the degree of upward warping in the radial flow section of the pressure recovery curve when considering polymer elasticity is greater than the curve which not considering polymer elasticity. The relaxation time, power-law index, polymer injection concentration mainly affect the radial flow stage of the well testing curve. The relaxation time, power-law index, polymer injection concentration and other polymer flooding parameters mainly affect the radial flow stage of the well testing curve. The larger the polymer flooding parameters, the greater the degree of upwarping of the radial flow derivative curve. This model has important reference significance for well-testing research in polymer flooding oilfields.

Thermal gradient and elastic dependence of induced charge electro-osmosis in viscoelastic fluids

Induced charge electro-osmosis has notable implementation possibilities in thermal management and efficient electrokinetic micropumps. We present the coupled numerical implementation around a polarized cylinder subject to an external electric field with the influence of different polymer elasticity and thermal gradients. The azimuthal velocity, flow types, kinetic energy, elastic energy, ion transport behavior, and heat transfer capability are investigated in detail. The results show that the inflow and outflow rates approximately overlap for a typical small voltage limit ϕ < 0.1. The Rayleigh number (Ra) significantly influences the elastic energy accumulation and evolution time to the final steady state. The thermal buoyancy forces are not sufficient to create typical thermogravitational convection with passive heat transfer when Ra < 1.3 × 10−3, resulting in heat diffusion and electro-osmosis velocity dominating the temperature distribution. The Nusselt number (Nu) plot with a weak viscoelastic effect implies an asymptotic Nu=0.44+2.65Ra0.35 relation. Relevant results open possibilities for enhanced mixing and heat transfer in microdevices, providing insight into barriers to the non-Newtonian nature of electrokinetic dynamics.

Communication and technological solutions regarding the construction of shelter objects at underground railway stations in fractured and water-logged rocks

The purpose of the work is to substantiate the choice of locations of underground shelter objects for the people protection during the warlike situation and methods and facilities for ensuring their stability and isolation, and to develop a combined supporting scheme taking into account mining and geological conditions. It is proposed to arrange the shelter objects in the vicinity of the boarding platforms of the underground railway stations connecting them with the passages, means for walking downstairs and upstairs and a transport network and providing areas for the long-term stay of people, areas for sleeping and eating, shower room, medical, shopping and other necessary blocks. The shelter should be connected to the networks of the underground railway station - electricity supply, water supply and drainage, ventilation and air conditioning. Sleeping areas should be built in the form of individual compartments and arranged in several tiers along the walls of the shelter object. This arrangement of underground objects will make it possible to create a single complex (the shelter object and subway station), reduce the total cost of the shelter construction, speed up the evacuation of people in the event of natural or man-made disasters or air strikes, and ensure a long-term comfortable stay for people. Load on supporting and parameters of roof-bolting systems were calculated for three categories of stability, which correspond to the conditions of the construction of underground railways in the Ukrainian crystalline shield. An algorithm for calculating parameters of the strengthened insulating-reinforcing protection system was built, which takes into account three types of support - rock-bolt structure, insulating-reinforcing rock-polymer layer and tubing. The developed technological solutions for the construction of underground objects assumes pre-bolting of their vaulted part according to a scheme which strengthens the interaction between the rows of bolts, improves the condition of the roof of the object, and ensures protection of the roadway and unsecured part near it during construction of the roadway. The rock-polymer layer protects the tubing against metal corrosion and leaching of concrete under the influence of groundwater, and, due to the high adhesiveness of the polymer resin, also binds the rock-bolt structure, the insulating-reinforcing rock-polymer layer and the tubing into a single reinforced system, which distributes the load around the object's perimeter. The use of modern elastic polymer resins in the protection system will contribute to resisting the alternating loads that spread in the soil during surface explosions, and ensures long-term stability and waterproofing of shelter object. The results of the research can be used in the development of scientific prerequisites for the improvement of methods and means of construction of underground shelter objects in order to ensure the safety of their operation in case of emergency situations. Keywords: underground structures, underground railway station, support, bolts, polymer resins.