Acrylic Elastomer Research Articles

A piezoresistive dielectric elastomer switch consisting of inkjet-printed carbon black

The piezoresistive effect is a key physical property utilized in soft and stretchable electronics, functioning as intrinsic electromechanical sensors. However, most conventional piezoresistive sensors can only passively measure and quantify external stimuli. To address these limitations, this work integrates an inkjet-printed piezoresistive pattern and a dielectric elastomer actuator (DEA) into a single monolithic dielectric elastomer film, creating a dielectric elastomer switch (DES). This DES can realize dramatic resistance changes along with DEA actuation, leveraging DEA-driven piezoresistivity for active and effective circuit control and signal processing. Theoretically, the DES operates by exhibiting resistance change through the periodic compression induced by DEA actuation. Experimentally, the piezoresistive pattern and the DEA electrodes were fabricated on an acrylic dielectric elastomer (VHB) using inkjet-printed piezoresistive carbon black (CB) and manually brushed conductive grease, respectively. The optimized DES demonstrated approximately 3.77 (±0.11) orders of magnitude in resistance change at a DEA frequency of 0.1 Hz. Compared to previously reported methods (smearing and stamping), inkjet-printed CB patterns showed significant improvements. These included negligible Joule heating impact, precise digital fabrication control, larger resistance change (up to 3.77 orders of magnitude), faster response speeds to DEA actuation (∼0.25 s for 3 orders of magnitude in resistance change), and greater durability (operating at 0.5 Hz for 112 min). Scanning electron microscopy (SEM) characterization revealed that these improvements were attributed to a more uniform distribution of conductive “CB islands” and appropriate non-conductive gap size among them. For demonstrating the applications of DES, it was employed for LED control, DEA-based soft gripper control, and as a multiplexer for signal processing.

Enhancement of controllable circular actuator using graphene oxide particles

ABSTRACT This work aims to study the responsive expansion of graphene oxide- acrylic elastomer (GO-Acry ER elastomer) under applied electric field. The GO was synthesized from graphite (GP) by using Hummer’s method based on various the ratios of GP to oxidizing agent namely potassium permanganate. GO-Acry ER elastomer was prepared by painted GO as the polarized particle on circular Acry ER as elastomer matrix. The optimum condition of synthesized GO was 1:2 ratios of GP: oxidizing agent which provided a more crystallinity, smaller particle size, and higher pore volume. The circular actuation response of GO-Acry ER elastomer was stimulated by applying external stimuli under various electric field strengths and GO characteristics. The expansion of the GO-Acry ER elastomer increased with an increasing external electric field strength. The GO-Acry ER elastomer under adding GO of 1:2 ratios was the largest expansion with 50% strain under applied electric field of 300 kV/mm. When the electric field strength was > 300 kV/mm, the ER elastomer shrank owing to electrical breakdown. Thus, GO is a suitable choice due to its ease of preparation and fast electro-responsive properties.

A poly(L-lactic Acid)-based flexible piezoelectric energy harvester with micro-zigzag structures

Piezoelectric energy harvester (PEH) holds great potential for flexible electronics and wearable devices. However, the power conversion efficiency of flexible PEH (fPEH) has often been a limiting factor, especially under variable excitation. Herein, we propose a practical solution: a poly(L-lactic acid)-based fPEH with 3D-printed micro-zigzag structures. This design not only broadens the operational bandwidth and enhances low-frequency response but also offers a tangible improvement in the power conversion efficiency of fPEH. The micro-zigzag structure was designed and fabricated using a digital light processing 3D printing technique with acrylates, a method that is readily accessible to researchers and engineers in the field. Mechanical properties of the 3D-printed acrylic elastomers with different compositions were investigated to obtain the material parameters, and then fPEH with the sandwich structure was fabricated via sputtering and packaging. Subsequently, numerical simulation was conducted on the micro-zigzag structures to determine the structure sizes and oscillation frequencies of fPEH. Finally, four micro-zigzag structures with 3-, 4-, 5- and 6 mm lengths were tested to obtain oscillation frequencies of 51, 37, 22, and 21 Hz consistent with the simulation. The output voltages of fPEH are 11–30 mV with the load ranges of 60–100 MΩ. Stability evaluation showed that the fPEH can work under low frequency (<100 Hz) and broadband conditions. The micro-zigzag structure provided new insights for the design of fPEH, paving the way for more efficient and practical energy harvesting solutions in the future.

Role of acrylate terpolymers in flow assurance studies of crude oil

Paraffinic crude oil causes deposition in the pipeline at low temperatures which hinders the flow during pipeline transportation. The primary technique for mitigation of paraffin deposition is chemical treatment. Polymeric chemical additives have gained considerable attention as flow improvers for waxy crude oil. Terpolymer application for flow assurance is a novel approach since terpolymers are seldom used as chemical additives for crude oil. Current research aims to synthesize four acrylate terpolymers with different alkyl pendant chains and study their effect on the rheological behavior of crude oil. The structure of additives was validated and their depression effect was investigated. The results of the investigation revealed that the additives showed significant decrease in pour point (ΔPP = 21 °C for CO-1 and 15 °C for CO-2) at a dose of 1000 ppm for CO-1 and 2000 ppm for CO-2. These results were also supported by rheological data which exhibited a significant reduction in viscosity (>75%) of both the crude oils which showed the efficiency of additives as flow improvers. Moreover, the cold finger test displayed excellent paraffin inhibition efficiency of synthesized additives (66 and 52% for CO-1 and CO-2, respectively). The investigation demonstrated a promising role of terpolymers as flow improvers for waxy crude oil.

Higher-Order Structural Analysis of a Transparent and Flexible High Thermal Conductive Liquid Crystalline Elastomer Sheet and Its Composite.

Transparency, flexibility, and high thermal conductivity are trade-offs. Specifically, we have investigated a cross-linked acrylic liquid crystal elastomer (LCE) that exhibits both transparency and flexibility while maintaining a high level of thermal conductivity. The transparent monodomain LCE sheet was achieved through a process of stretching an initially opaque polydomain sheet to 80% elongation and subsequently subjecting it to photocuring. The thermal conductivity in the stretching direction (x) of the monodomain LCE sheet was found to be 1.8 times higher than that of the prestretched polydomain sheet, consistent with findings from previous studies. However, in the orthogonal direction (y) to the stretching (x) direction, the thermal conductivity exhibited an even higher value, being 1.7 times greater than in the x-direction, with a value of 3.0 W/(m·K). This unique observation prompted us to conduct further investigation through higher-order structural analysis of these LCE sheets using 2D wide-angle X-ray scattering (WAXS) analysis. In the transparent sheet, the LCE molecules were aligned in the sheet in the stretching x-direction (monodomain structure) for the out-of-plane direction. However, in the in-plane x-direction, the molecular plane spacing exhibited random orientation at a period of 0.45 nm. In contrast, within the y-direction of the inner layer, the molecular plane spacing exhibited a uniaxial horizontal orientation at the same period length as in the x-direction. The heat energy entering into the y-direction once spreads to the x-direction, but it was considered that the reason for the higher thermal conductivity to the y-direction would be forming covalent bonds that function as new heat transmission paths, in the direction intersecting to the x-direction during photocuring. Therefore, we concluded that the synergistic effect of the high level of the ordered inner structure and covalent bonding structure due to cross-linking in the y-direction contributes to its higher thermal conductivity compared to that in the x-direction, which exhibits a random in-plane structure. Additionally, we have fabricated an LCE composite sheet filled with 75 vol % of alumina particles using a polydomain-type LCE as the base material. The composite sheet exhibits remarkable thermal conductivity in the thickness direction, measuring at 9.8 W/(m·K), while maintaining a flexibility characterized by an elastic modulus of 70 MPa. This thermal conductivity surpasses that of a nonmesogenic acrylic composite sheet with identical alumina particle filling, which measured at 3.9 W/(m·K), more than twice as much. The presence of the mesogen skeleton has been demonstrated to enhance heat transfer, even within soft composites, by facilitating the formation of an ordered structure.

Recyclable Tough Adhesive Sheets with Movable Cross-Links for Sustainable Use.

Acrylic adhesive sheets have been used for many applications, from popular seal materials to high-end electrical devices. One of the basic and critical design features of adhesives is effective covalent cross-linking for superior adhesive properties. On the other hand, covalent cross-linking prevents reuse or recycling of the adhesive. This makes the adhesive sheets insoluble and poorly workable. For development of sustainable adhesives, we investigated the adhesive sheets based on acrylic elastomers with "Movable Cross-links" (M-PEA-CD (0.5)) copolymerized with 0.5 mol % cyclodextrin monomers. The peel strength and creep resistance of M-PEA-CD (0.5) were greater than those of adhesives (N-PEA) without any cross-links. M-PEA-CD (0.5) was recyclable via dissolution in ethyl acetate. Furthermore, the recycled M-PEA-CD (0.5) from solution exhibited the same adhesion properties as virgin M-PEA-CD (0.5). Spectroscopic and mechanical measurements indicated that topological cross-linking with Cyclodextrin (CD) moieties generated novel recyclable adhesive sheets without restricting the polymer main chains, unlike covalent cross-linking (CC-PEA). The movable cross-links were maintained in both the solid state and in solution, which allowed recycling of the elastomer via simple methods.

Space Charge Behavior in Acrylic Elastomer Under DC Voltage With and Without Stress

Space Charge Behavior in Acrylic Elastomer Under DC Voltage With and Without Stress

Topology Controlled All‐(Meth)acrylic Thermoplastic Elastomers by Multi‐Functional Lewis Pairs‐Mediated Polymerization

AbstractIt remains challenging to synthesize all‐(meth)acrylic triblock thermoplastic elastomers (TPEs), due to the drastically different reactivities between the acrylates and methacrylates and inevitable occurrence of side reactions during polymerization of acrylates. By taking advantage of the easy structural modulation features of N‐heterocyclic olefins (NHOs), we design and synthesize strong nucleophilic tetraphenylethylene‐based NHOs varying in the number (i.e. mono‐, dual‐ and tetra−) of initiating functional groups. Its combination with bulky organoaluminum [iBuAl(BHT)2] (BHT=bis(2,6‐di‐tBu‐4‐methylphenoxy)) constructs Lewis pair (LP) to realize the living polymerization of both acrylates and methacrylates, furnishing polyacrylates with ultrahigh molecular weight (Mn up to 2174 kg ⋅ mol−1) within 4 min. Moreover, these NHO‐based LPs enable us to not only realize the control over the polymers’ topology (i.e. linear and star), but also achieve triblock star copolymers in one‐step manner. Mechanical studies reveal that the star triblock TPEs exhibit better mechanical properties (elongation at break up to 1863 % and tensile strength up to 19.1 MPa) in comparison with the linear analogs. Moreover, the presence of tetraphenylethylene group in the NHOs entitled the triblock TPEs with excellent AIE properties in both solution and solid state.

Topology Controlled All-(Meth)acrylic Thermoplastic Elastomers by Multi-Functional Lewis Pairs-Mediated Polymerization.

It remains challenging to synthesize all-(meth)acrylic triblock thermoplastic elastomers (TPEs), due to the drastically different reactivities between the acrylates and methacrylates and inevitable occurrence of side reactions during polymerization of acrylates. By taking advantage of the easy structural modulation features of N-heterocyclic olefins (NHOs), we design and synthesize strong nucleophilic tetraphenylethylene-based NHOs varying in the number (i.e. mono-, dual- and tetra-) of initiating functional groups. Its combination with bulky organoaluminum [iBuAl(BHT)2] (BHT=bis(2,6-di-tBu-4-methylphenoxy)) constructs Lewis pair (LP) to realize the living polymerization of both acrylates and methacrylates, furnishing polyacrylates with ultrahigh molecular weight (Mn up to 2174 kg ⋅ mol-1) within 4 min. Moreover, these NHO-based LPs enable us to not only realize the control over the polymers' topology (i.e. linear and star), but also achieve triblock star copolymers in one-step manner. Mechanical studies reveal that the star triblock TPEs exhibit better mechanical properties (elongation at break up to 1863 % and tensile strength up to 19.1 MPa) in comparison with the linear analogs. Moreover, the presence of tetraphenylethylene group in the NHOs entitled the triblock TPEs with excellent AIE properties in both solution and solid state.

Edible Soft Actuators Based on Konjac Glucomannan for Underwater Operation

Soft robots are being increasingly developed and deployed for underwater applications such as exploration, monitoring, and rescue owing to their innate compliance, mechanical and chemical stability, and waterproof properties. However, they are still predominantly manufactured using silicones and acrylic elastomers, which pose environmental risks due to their limited biodegradability. To tackle this issue, a method for manufacturing water‐resistant, liquid‐driven soft actuators made from a novel type of konjac glucomannan (KGM) is presented, which is plant‐derived, insoluble, and edible. The material offers impressive stretchability, reaching up to 67.2% of its initial length, surpassing previous related work, and withstands over a 1000 cycles of tensile stress. Using this material, we develop soft actuators that can bend up to 47.1°, and the maximum blocking force of 0.1 N is achieved with a pressure input of 20 kPa. A gripper that is capable of grasping various objects underwater is also evaluated. In essence, this article introduces a sustainable and environmentally friendly alternative to conventional soft robotic materials, paving the way for innovative and eco‐conscious underwater applications. The utilization of edible, water‐resistant materials like konjac provides a promising solution to reduce pollution and mitigate negative environmental impacts associated with traditional underwater soft robots.

A Quad‐Unit Dielectric Elastomer Actuator for Programmable Two‐Dimensional Trajectories

Resonant actuation and multi‐degree‐of‐freedom (DoF) actuation can optimize the output matrices and greatly expand the versatility of dielectric elastomer actuators (DEAs) for practical applications. However, developing a multi‐DoF resonant DEA that benefits both from the maximized stroke outputs in resonant actuation and the versatility in multi‐DoF actuation remains a challenging task due to the slow responses of the widely adopted acrylic elastomers and the exponentially scaled complexity in the nonlinear dynamics. Herein, a multi‐DoF resonant DEA is reported by adopting four radially organized planar DE units fabricated by low‐loss silicone elastomers to output versatile programmable two‐dimensional quasi‐static and resonant trajectories. The rich nonlinear dynamics of the proposed quad‐unit DEA (QUDEA) are characterized and the critical parameters for two‐dimensional trajectory programming are uncovered through extensive modeling and experimental studies. To showcase the two‐dimensional trajectory programming capabilities of the QUDEA, demonstrations of Chinese characters writing and hummingbird flapping patterns mimicking using the proposed QUDEA are developed. The proposed QUDEA is expected to have potential in various applications such as in experimental biology, biomimetic robotics, and industrial manufacturing devices.

Enhancement of dielectric properties of acrylic resin elastomer‐based composites with SiO2 loaded carbon nanotubes

AbstractThe inherent balance between dielectric constant and loss restricts the actual usage of dielectric elastomer actuators with high actuation strains, proposing a method that can break this trade‐off has been an urgent query. In this work, silica‐loaded carbon nanotubes (called SiO2@CNT) were prepared as dopants for acrylic resin elastomers (abbreviated as ARE) using the sol–gel method, and the obtained SiO2@CNT/ARE composites reached a dielectric constant of 282.5 at 100 Hz at a filler content of 3.22 vol%, which is 86 times higher than that of the pure ARE, whereas the dielectric loss remains at 0.17. The equilibrium between dielectric constant and loss is broken mainly based on the loading of SiO2 which inhibits the formation of carbon nanotube conductive network and concurrently reinforces the compatibility of the filler with ARE. Such a design offers a generalizable strategy for the subsequent preparation of polymer‐based composite films with excellent dielectric properties.Highlights Preparation of fillers with excellent dispersibility in the organic phase. The ARE‐based composites exhibit excellent dielectric properties at 100 Hz. The mechanism of increase in dielectric constant is explained using two models.

Morphological evolution and property changes of acrylate rubber/polyacetal thermoplastic vulcanizates during dynamic vulcanization process

AbstractA new type of thermoplastic vulcanizates (TPV) that is resistant to hot oil, high temperature, and aging was prepared using acrylate elastomer (ACM) and polyoxymethylene (POM) as raw materials. The phase transition process and micromorphology development of the blends with the change of dynamic vulcanization (DV) time, and to illustrate the effects of the phase transition and the degree of elastomer phase crosslinking on the macroscopic properties of TPV were investigated. It was shown that ACM crosslinking occurs continuously during 0–8 min of DV, whereas the phase inversion process occurs predominantly during 0–3 min. In contrast, the cross‐section of the blends after phase inversion is flat, The constant elongation stress under small deformation, hardness, and permanent deformation after break are reduced, and the elongation at break, nonrelaxable modulus, and aging resistance are improved. The increase in the degree of vulcanization of the ACM phase resulted in a significant increase in the modulus of the blends under large deformation, an increase in the nonrelaxable modulus and relaxable modulus, an increase in the aging resistance, and a decrease in the elongation at tear were observed.

3D nanofabricated soft microrobots with super-compliant picoforce springs as onboard sensors and actuators.

Microscale organisms and specialized motile cells use protein-based spring-like responsive structures to sense, grasp and move. Rendering this biomechanical transduction functionality in an artificial micromachine for applications in single-cell manipulations is challenging due to the need for a bio-applicable nanoscale spring system with a large and programmable strain response to piconewton-scale forces. Here we present three-dimensional nanofabrication and monolithic integration, based on an acrylic elastomer photoresist, of a magnetic spring system with quantifiable compliance sensitive to 0.5 pN, constructed with customized elasticity and magnetization distributions at the nanoscale. We demonstrate the effective design programmability of these 'picospring' ensembles as energy transduction mechanisms for the integrated construction of customized soft micromachines, with onboard sensing and actuation functions at the single-cell scale for microrobotic grasping and locomotion. The integration of active soft springs into three-dimensional nanofabrication offers an avenue to create biocompatible soft microrobots for non-disruptive interactions with biological entities.

Flexibly stretchable acrylic resin elastomer films for efficient electromagnetic shielding and photothermal conversion

A retractable, stretchable shielding device with large areal strain variability is essential for intelligent wearable electronics.

Synthesis of high molar mass all-(meth)acrylic thermoplastic elastomers by photo-iniferter RAFT polymerisation

The synthesis of PMMA-b-PnBA-b-PMMA triblock copolymers using photoiniferter reversible addition-fragmentation chain transfer (PI-RAFT) polymerisation is reported. By utilising a combination of green and blue LED irradiation, copolymers with high molar...

Flexible strain sensors based on silver nanowires and UV-curable acrylate elastomers for wrist movement monitoring

This article uses innovative UV-curable acrylate elastomer with AgNWs to develop flexible strain sensors for wrist movement monitoring.

PH-Sensitive Acrylic Terpolymers for the Coating of Orally Administered Drugs Used for Colonic Release.

Polymeric coatings are a promising option for the development of delivery systems for orally administered drugs. However, the gastrointestinal conditions to which they are subjected, which include low pH and solubility as well as peristaltic movements, can limit their applications. In this work, different formulations of polymeric coatings were produced using pH-sensitive materials consisting of copolymers of methyl acrylate, methyl methacrylate, and methacrylic acid. The polymers were synthesized by the emulsion polymerization technique, obtaining small average particle sizes (56-190 nm), molecular weights between 200,000 and 400,000 g/mol, and a glass transition temperature above 35 °C, which are suitable for film formation at room temperature. Thus, they were assessed as coatings for hydroxypropyl methylcellulose capsules (HPMC) using the immersion method, showing adequate capacity to protect the capsule at gastric pH (pH 1.2) and dissolve at the simulated intestinal pH (pH= 7.2). In particular, the higher the content of the acidic monomer, the higher the release time of the test molecule contained in the acrylic terpolymer-coated HPMC capsules proposed, which was a curcuminoid derivative due to their bright color and potential medical benefits. In addition, a minimum number of immersions was required for coating the HPMC capsules at high acidic concentrations, which further facilitates the delayed release needed for colonic treatment. However, too high proportions of methacrylic acid may result in cytotoxicity issues. Consequently, a biocompatible formulation containing a proportion of methyl acrylate, methyl methacrylate, and methacrylic acid of 7:3:3 is proposed as the most adequate for colonic release. Thus, by chemically modulating the molar percentages of the acrylic monomers, it was possible to obtain tailored acrylic terpolymer coatings with different characteristics and desired properties in order to modulate the release kinetics of an active substance in a colonic environment.

Effectiveness Of Skin Barrier Acrylate Terpolymer On Medical Adhesive Related To Skin Injury (MARSI) in Children At Pediatric Intensive Care Unit Dr. Cipto Mangunkusumo Hospital

BACKGROUND: For a long time, the use of medical adhesives in invasive device installation procedures can cause medical adhesive related to skin injury (MARSI) in children; in order to minimize the risk of MARSI incidents, so that a skin barrier is needed before applying the adhesive. OBJECTIVE: The purpose of this study is to determine the effectiveness of acrylate terpolymer skin barrier against medical adhesive related to skin injury (MARSI) prevention in children who are treated at the intensive care unit. METHOD: This study used a true experimental design which involved 46 children; it was divided into an intervention group of 24 respondents and a control group of 22 respondents who were treated by using medical adhesive due to the procedure for inserting an endotracheal tube and nasogastric tube. Samples were taken by using random sampling technique. The risk level of skin injury was assessed by using the Braden Q scale and the MARSI incidents were observed by using the observational format. RESULT: The results showed that the acrylate terpolymer skin barrier was effective in reducing the MARSI in children who were treated at the intensive care unit with having a p-value of 0.03 (α &lt;0.05). The use of an acrylate terpolymer skin barrier can be recommended to minimize the incidence of MARSI in children. CONCLUSION: The use of acrylate terpolymer skin barrier significantly minimizes the incidence of MARSI in children.

Rapid fabrication of physically robust hydrogels.

Hydrogel materials show promise for diverse applications, particular as biocompatible materials due to their high water content. Despite advances in hydrogel technology in recent years, their application is often severely limited by inadequate mechanical properties and time-consuming fabrication processes. Here we report a rapid hydrogel preparation strategy that achieves the simultaneous photo-crosslinking and establishment of biomimetic soft-hard material interface microstructures. These biomimetic interfacial-bonding nanocomposite hydrogels are prepared within seconds and feature clearly separated phases but have a strongly bonded interface. Due to effective interphase load transfer, biomimetic interfacial-bonding nanocomposite gels achieve an ultrahigh toughness (138 MJ m-3) and exceptional tensile strength (15.31 MPa) while maintaining a structural stability that rivals or surpasses that of commonly used elastomer (non-hydrated) materials. Biomimetic interfacial-bonding nanocomposite gels can be fabricated into arbitrarily complex structures via three-dimensional printing with micrometre-level precision. Overall, this work presents a generalizable preparation strategy for hydrogel materials and acrylic elastomers that will foster potential advances in soft materials.