High-performance Polymeric Materials Research Articles

Bulky Phosphazenium Salt Controlling Chemoselective Terpolymerization of Epoxide, Anhydride and CO2: From Well-Defined Block to Truly Random Copolymers.

Copolymers with precise compositions and controlled sequences are great appealing for high-performance polymeric materials, but their synthesis is very challenging. In this study, tetrakis[tris(dimethylamino)phosphoranylidenamino] phosphonium chloride (P5Cl) and triethylboron (TEB) were chosen as the binary catalyst to synthesize both well-defined block and truly random poly(ester-carbonate) copolymers via the one-pot/one-step terpolymerization of epoxide/anhydride/CO2 under metal-free conditions. The bulky nature of phosphazenium cation not only led to loose cation-anion pairs and enhanced the reactivity, but also provided the chain-end an appropriate protection and improved the controllability. In particular, P5Cl/TEB with a molar ratio of 1/0.5 showed an extraordinary chemoselectivity for ring-opening alternating copolymerization (ROAC) of cyclohexene oxide (CHO) and phthalic anhydride (PA) first and then ROAC of CHO/CO2. Thus, well-defined block polyester-polycarbonate copolymers were synthesized by CHO/PA/CO2 terpolymerization. The chemoselectivity was easily tuned and the ROAC of CHO/PA and ROAC of CHO/CO2 occurred simultaneously with P5Cl/TEB=1/2, producing truly random poly(ester-carbonate) copolymers from CHO/PA/CO2. In addition, this P5Cl/TEB catalyst and the strategy to regulate its chemoselectivity are versatile for various anhydrides, epoxides and initiators. Thus, poly(ester-carbonate) copolymers with varying sequences, compositions, and topologies are successfully synthesized, making it possible to compare their properties and to expand their applications.

Super Tough PA6/PP/ABS/SEBS Blends Compatibilized by a Combination of Multi-Phase Compatibilizers.

Development of multi-component blends to prepare high-performance polymer materials is still challenging, and is a key technology for mechanical recycling of waste plastics. However, a multi-phase compatibilizer is prerequisite to create high-performance multi-component blends. In this study, POE-g-(MAH-co-St) and SEBS-g-(MAH-co-St) compatibilizers are prepared via melt-grafting of maleic anhydride (MAH) and styrene (St) dual monomers to polyolefin elastomer (POE) and poly [styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS), respectively. Subsequently, these compatibilizers are utilized to compatibilize the PA6/PP/ABS/SEBS quaternary blends through melt-blending. When POE-g-(MAH-co-St) and SEBS-g-(MAH-co-St) are added, respectively, both can promote the distribution of the dispersed phases, significantly reducing the dispersed phase size. When adding 10 wt% POE-g-(MAH-co-St) and 10 wt% SEBS-g-(MAH-co-St) together, compared to the non-compatibilized blend, the fracture strength, fracture elongation, and impact strength surprisingly increased by 106%, 593%, and 823%, respectively. It can be attributed to the hierarchical interfacial interactions which facilitate gradual energy dissipation from weak to strong interfaces, resulting in the improvement of mechanical properties. The synergistic effect of the enhanced phase interfacial interactions and toughening effect of elastomer compatibilizer achieved simultaneous growth in strength and toughness.

Photoexcitation-Assisted Molecular Doping for High-Performance Polymeric Thermoelectric Materials.

Molecular doping plays a crucial role in modulating the performance of polymeric semiconductor (PSC) materials and devices. Despite the development of numerous molecular dopants and doping methods over the past few decades, achieving highly efficient doping of PSCs remains challenging, primarily because of the inadequate matching of frontier energy levels between the host polymers and the dopants, which is critical for facilitating charge transfer. In this work, we introduce a novel doping method termed photoexcitation-assisted molecular doping (PE-MD), capable of transcending limitations imposed by energy level disparities through the mediation of efficient photoinduced electron transfer between polymers and dopants. This approach significantly amplifies the electrical conductivity of the PDPP4T polymer, increasing it by more than 4 orders of magnitude to a maximum value of 349.67 S cm-1. Given that only the irradiated region experiences a substantial increase in doping level, the PE-MD process facilitates the photoresist-free and precise patterning of doped polymers at a resolution down to 1 μm. Furthermore, the enhanced electrical conductivity of the photoexcitation-assisted molecularly doped PDPP4T film promotes efficient thermoelectric conversion, yielding an impressive initial power factor of 226.1 μW m-1 K-2 and a figure-of-merit (ZT) of 0.18, accompanied by improved thermal and ambient stability. The PE-MD strategy not only remarkably elevates the doping level of PSCs toward efficient thermoelectric conversion but also preserves the easy processability of flexible and integrated devices.

Reactive Processing of Furan-Based Monomers via Frontal Ring-Opening Metathesis Polymerization for High Performance Materials.

Frontal ring-opening metathesis polymerization (FROMP) presents an energy-efficient approach to produce high-performance polymers, typically utilizing norbornene derivatives from Diels-Alder reactions. This study broadens the monomer repertoire for FROMP, incorporating the cycloaddition product of biosourced furan compounds and benzyne, namely 1,4-dihydro-1,4-epoxynaphthalene (HEN) derivatives. A computational screening of Diels-Alder products is conducted, selecting products with resistance to retro-Diels-Alder but also sufficient ring strain to facilitate FROMP. The experiments reveal that varying substituents both modulate the FROMP kinetics and enable the creation of thermoplastic materials characterized by different thermomechanical properties. Moreover, HEN-based crosslinkers are designed to enhance the resulting thermomechanical properties at high temperatures (>200°C). The versatility of such materials is demonstrated through direct ink writing (DIW) to rapidly produce 3D structures without the need for printed supports. This research significantly extends the range of monomers suitable for FROMP, furthering efficient production of high-performance polymeric materials.

Molecular Dynamics Simulation on Polymer Tribology: A Review

A profound comprehension of friction and wear mechanisms is essential for the design and development of high-performance polymeric materials for tribological application. However, it is difficult to deeply investigate the polymer friction process in situ at the micro/mesoscopic scale by traditional research methods. In recent years, molecular dynamics (MD) simulation, as an emerging research method, has attracted more and more attention in the field of polymer tribology due to its ability to show the physicochemical evolution between the contact interfaces at the atomic scale. Herein, we review the applications of MD in recent studies of polymer tribology and their research focuses (e.g., tribological properties, distribution and conformation of polymer chains, interfacial interaction, frictional heat, and tribochemical reactions) across three perspectives: all-atom MD, reactive MD, and coarse-grained MD. Additionally, we summarize the current challenges encountered by MD simulation in polymer tribology research and present recommendations accordingly, aiming to provide several insights for researchers in related fields.

Curing behavior and thermal properties of phthalonitrile resins derived from benzyl alcohol

A series of phthalonitrile resins were synthesized through innovative reactions between compounds derived from benzyl alcohol and nitro functionalities. The synthesis commenced with the reaction of specific alcohols (4-hydroxybenzyl alcohol, vanillyl alcohol, and 1,4-benzenedimethanol) with 4-nitrophthalonitrile, resulting in the formation of three phthalonitrile monomers. These monomers were then cured using 4,4′-diaminodiphenyl ether as a curing agent, resulting in the phthalonitrile resins, namely BCDPN, XCDPN, and DBDPN. The investigation revealed that these resins possessed remarkable properties, particularly in terms of thermal stability and dynamic mechanical behavior. Notably, BCDPN exhibited superior thermal stability, achieving a Td10 % of 534 °C. XCDPN and DBDPN demonstrated outstanding dynamic mechanical properties, characterized by a storage modulus exceeding 3400 MPa. The synthesis approach, leveraging compounds derived from benzyl alcohol and nitro reactions, not only broadens the scope of raw materials but also offers novel and alternative preparation strategies for phthalonitrile resins. This study enhances the understanding of the curing behavior and thermal properties of these resins, providing valuable insights into their potential applications in high-performance polymer materials.

Investigation on preparation and tribology of poly ether ether ketone nanocomposite with transition metal doped zirconium dioxide

Composite materials are currently one of the most active study fields in modern technology. Their promising properties make them appropriate for a wide range of industrial applications including aerospace, automotive, construction, sports, bio-medical, and many more. These materials have amazing structural and mechanical features such as high strength-to-weight ratio, resistance to chemicals, fire, corrosion, and wear, as well as being cost-effective to produce. Poly-ether-ether-ketone (PEEK), a high performance polymeric materials, is increasingly being employed to replace metal elements in car engines and transmissions. Zirconium oxide (ZrO2), often known as zirconia, is a high-tech ceramic substance that is widely employed in the manufacture of various hard ceramics. The various physical and chemical properties of ZrO2 have been properly tailored for a given use by inserting transition metals (dopants) into the ZrO2 crystalline structure. In this work, the nano-composite of PEEK and transition metal doped Zirconium Dioxide is prepared. The composite was subsequently subjected to vital characterizations and tribological testing. The characterization validated the amalgam of modified ZrO2 with PEEK. The investigation has shown that PEEK reinforcement with modified ZrO2 has desired qualities for use in tribological applications

Effect of pyridine group in dithienyl pyrrole chain on electrochemical and spectrochemical properties: An excellent electrochromic polymer

In the present research, a novel high-performance polymeric electrochromic materials consisting of pyridine with the ditihenyl pyrrole derivative (SNS) was achieved by the Paal-Knorr reaction, and its conjugated homopolymer, pTPN, and copolymer with EDOT were obtained in the medium of 0.1 M LiClO4/AN via electroanalytical methods. Although high electrochemical and spectrochemical properties were expected for the polymer chain in the copolymerization process involving the EDOT comonomer, for this study, the homopolymer was determined to have exhibited excellent electrochemical properties even without the need for this process. The pTPN exhibited favorable kinetic properties, especially high optical contrast (87 %) and desired color efficiency (837.7 cm2 C−1). Compared to other SNS derivatives in the literature, the obtained polymer pTPN had the highest optical contrast and color efficiency. In conclusion, this study has supplied a new structural design for the electrochromic polymers that might be beneficial for understanding the dithienyl pyrrole conjugated polymers behaviors composed of the pyridine units.

Flame retardant behavior of bio-based epoxy resin bearing pyridazinone and dynamic ester bond via self-blow-out and vesicular carbon formation

Aromatic nitrogen heterocyclic structure is a key building block of high-performance polymer materials and nitrogen-doped porous carbons, yet systematic studies on its flame-retardant effects and carbonization mechanisms in thermoset materials is still lacking. Here, a pyridazinone embedded bio-based epoxy resin (CSPZ-EP) cured by 4,4ʹ-methylenedianiline (DDM) was prepared. Benefiting from the rigid biphenyl-like pyridazinone structure and the high cross-linking density originated from the self-catalyzed transesterification, the cured CSPZ-EP/DDM can easily pass the UL-94 test with a V-0 rating suggesting excellent intrinsic flame retardancy. The cone calorimeter results further demonstrated that the peak heat release rate, the total heat release and flame growth rate of CSPZ-EP/DDM were significantly reduced by 84.4 %, 28.4 % and 90.5 %, respectively, compared with those of bisphenol A epoxy resin. The higher graphitization degree of the char residues and a large amount of non-flammable pyrolysis gas ejection synergistically prevented the further spread of fire. Strong yet tough nitrogen-rich char layer formed after thermal ablation together with the renewable features and the facile preparation route of CSPZ-EP/DDM make it a potential precursor for heteroatom porous carbons.

Water-Assisted Contact Electrification Properties of Selected Polymers and Surface Functionalization Molecules: A Computational Study.

Motivated by the requirements of performance stability in environments of variable humidity, the focus of this study is on the effects and role of humidity-induced water molecules and ions in the contact electrification (CE) mechanisms of triboelectric materials. In particular, the compatibility of direct charge transfer-based CE and other generally known or proposed water molecules or OH/H3O ion-facilitated CE mechanisms was assessed for a set of high-performance polymeric materials and functionalization molecules. The first set of test mechanisms included OH/H3O ion adsorption at the low-humidity limit. The adsorption resulted in physisorption or H transfer involving reactions that were not fully compatible with charge affinity-driven CE reactions on the considered contact surfaces for both ions in terms of the potential increase of the resultant density of surface charge. An alternative mechanism, which yielded compatibility at a large humidity limit, consisted of free energy-driven segregation and separation of the ions. Further test mechanisms included water adsorption-induced charge transfer and two mechanisms pertinent to charged material transfer: adsorption modulation due to formation of water monolayers and water solvation-induced separation of polymer fragments. According to the obtained results, both mechanisms could be verified as viable contributors to enhanced charge transfer. Consequently, the results allowed for conclusions regarding the general applicability of different, water-assisted CE mechanisms and the selection of particular pairs of contact materials of similar type for optimum performance in humid environments.

Use of high-performance polymeric materials in customized low-cost robotic grippers for biomechatronic applications: experimental and analytical research

Advancements in materials science and 3D printing technologies have opened up new avenues for developing low-cost robotic grippers with high-performance capabilities, making them suitable for various biomechatronic applications. In this research, it has been explored the utilization of high-performance polymer materials, such as Polyetherketoneketone (PEKK), Polyethylene Terephthalate Glycol (PET-G) and MED 857 (DraftWhite), in the designing and developing of customized robotic grippers. The primary focus of made analyses was oriented on materials characterization, both experimentally and analytically. Computer-Aided Engineering (CAE) methods were employed to simulate bending experiments, allowing for a comprehensive analysis of the mechanical behavior of the selected materials. These simulations were validated through physical bending experiments using samples fabricated via 3D printing technologies, including Fused Filament Fabrication (FFF) for PET-G and PEKK, as well as Jetted Photopolymer (PolyJet) technology employing UV Resin for MED 857. The findings of this research provided advantages of utilizing advanced materials like PEKK in low-cost robotic grippers for biomechatronic applications. The experimental and analytical approaches offer valuable insights into material selection, design optimization, and the development of cost-effective high-performing robotic systems with a wide range of applications in the field of biomechatronics.

A Heat-Resistant Polymer Based on the Reversible Change in Polymer Skeleton Structure for Self-Anticounterfeiting.

Heat-resistant polymer materials have been widely used in many fields, but their anticounterfeit is still a significant challenge. This work has successfully constructed a heat-resistant polymer material that can achieve self-anticounterfeit. In response to changes in the external environment, the color of polymer changes from yellow-green to red reversibly, which is due to the fact that polymer material's backbone undergoes isomerization. Therefore, this high-performance polymer material can not only be used in a high-temperature environment for a long time but also achieve its anticounterfeit and be used in advanced security applications.

Shear bond strength characteristics on surface treatment modalities of CAD-CAM resin polymers.

The purpose of this in vitro study was to analyze the shear bond strength of composite resin to a commercially available high-performance polymer material for fixed, screw-retained full arch restorations. A total of 135 computer-aided design and computer-aided manufacturing, high-performance polymer (HPP) blocks were cut and obtained from discs (Trilor 95, Harvest Dental, Brea, CA). The samples were 10mm × 10mm × 10mm. The specimen surfaces were grouped as untreated (Group A), 50 μm Al2O3 (Group B), 110 μm Al2O3 (Group C), Rocatec (3M, St. Paul, MN) activated with silica-modified alumina oxide treatment (Group D); and trimmed coarsely with a carbide bur (Group E). Group A samples were used as controls. After surface treatments, the specimens were gently cleansed with oil-free steam and alcohol wipes. Surface conditioning was performed on all physically treated samples. The manufacturer's recommendations were followed for bonding composite resin to the samples with light-cured Visio.link (Bredent, Chesterfield, UK). Cylinders were veneered with composite resins (diameter 5mm, height 4mm) and polymerized on the specimen surfaces through plastic tubes. Twenty-seven specimens were used for each testing group and aging tests were performed. The experimental samples were thermocycled. Shear bond strength and scanning electron microscopic tests were performed. Means and standard deviations were calculated. Statistical analysis was performed with post-hoc Tukey tests. Statistical analysis revealed that there was a significant difference between the groups (p<0.001). The highest shear bond strengths were achieved for the specimens bonded with Visio.link without physical surface treatments (270.47MPa). The lowest bond strengths were found for specimen surfaces abraded with 110 μm Al2O3 (117.03 Mpa) CONCLUSIONS: The results of this laboratory study indicated that the specimens used with Visio.link as provided by the manufacturer had the highest shear bond strengths between the composite resin and high-performance polymer test specimens. Modifications of the high-performance polymer surfaces with carbide burs did not change bonding strengths with the composite materials.

Amphibious Polymer Materials with High Strength and Superb Toughness in Various Aquatic and Atmospheric Environments.

Herein, the fabrication of amphibious polymer materials with outstanding mechanical performances, both underwater and in the air is reported. A polyvinyl alcohol/poly(2-methoxyethylacrylate) (PVA/PMEA) composite with multiscale nanostructures is prepared by combining solvent exchange and thermal annealing strategies, which contributes to nanophase separation with rigid PVA-rich and soft PMEA-rich phases and high-density crystalline domains of PVA chains, respectively. Benefiting from the multiscale nanostructure, the PVA/PMEA hydrogel demonstrates excellent stability in harsh (such as acidic, alkaline, and saline) aqueous solutions, as well as superior mechanical behavior with a breaking strength of up to 34.8MPa and toughness of up to 214.2MJm-3 . Dehydrating the PVA/PMEA hydrogel results in an extremely robust plastic with a breaking strength of 65.4MPa and toughness of 430.9MJm-3 . This study provides a promising phase-structure engineering route for constructing high-performance polymer materials for complex load-bearing environments.

On the Mechanical, Thermal, and Rheological Properties of Polyethylene/Ultra-High Molecular Weight Polypropylene Blends.

The novel ultra-high molecular weight polypropylene (UHMWPP) as a dispersed component was melt blended with conventional high-density polyethylene (PE) and maleic anhydride grafted-polyethylene (mPE) in different proportions through a kneader. Ultra-high molecular weight polypropylene is a high-performance polymer material that has excellent mechanical properties and toughness compared to other polymers. Mechanical, thermal, and rheological properties were presented for various UHMWPP loadings, and correlations between mechanical and rheological properties were examined. Optimal comprehensive mechanical properties are achieved when the UHMWPP content reaches approximately 50 wt%, although the elongation properties do not match those of pure PE or mPE. However, it is worth noting that the elongation properties of these blends did not match those of PE or mPE. Particularly, for the PE/UHMWPP blends, a significant drop in tensile strength was observed as the UHMWPP content decreased (from 30.24 MPa for P50U50 to 13.12 MPa for P90U10). In contrast, the mPE/UHMWPP blends demonstrated only minimal changes in tensile strength (ranging from 29 MPa for mP50U50 to 24.64 MPa for mP90U10) as UHMWPP content varied. The storage modulus of the PE/UHMWPP blends increased drastically with the UHMWPP content due to the UHMWPP chain entanglements and rigidity. Additionally, we noted a substantial reduction in the melt index of the blend system when the UHMWPP content exceeded 10% by weight.

A facile strategy to improve the strength and toughness of high-performance polymers and recycling by dynamic Ni-coordination crosslinking

It is of great significance to enhance mechanical properties and thermal stability of high-performance polymers. A new coordination polymer film (Ni/PPy) with high tensile strength and excellent heat resistance has been successfully prepared via a palladium-catalyzed C-C coupling reaction. For newly synthesized polymer film, bipyridine is incorporated into polymer chains during the synthesis process and subsequently crosslinked by nickel acetate. More importantly, Ni-coordination can be removed by external pyrophosphate to recover the linear polymer, which endows the polymer with recyclability. This strategy is expected to be an effective means for increasing the mechanical properties and recyclability of high-performance polymer materials.

Influence of Microstructure on the Dynamic Behaviour of Polyurethane Foam with Various Densities

Polyurethane foam is reinforced with varying proportions of metal loads and other components to increase shock absorption and mechanical impact. The main objective is to develop high-performance polymeric materials based on polyurethane foam developed with different compositions and specific densities. We monitor the growth distances and temperatures of the polyurethane foam in time to reach the optimum formulations. We conduct static compression tests and investigate the effect of drop weight on the deformation of polyurethane foam structures by dropping a weight from a specified height. Dynamic collisions cause deformations of the polyurethane foam structure. After investigating the low weight, we found that polyurethane foams have a good absorption coefficient at certain frequencies. Dynamic stress-strain response curves are used to characterize different stress rates. High-stress levels and similar strains indicate a high resistance to shock. We follow the evolution of microstructure structures by scanning electron microscopy (SEM) to observe deformation and fracture behavior with reversibility and recovery.

Flexural Behavior of Biocompatible High-Performance Polymer Composites for CAD/CAM Dentistry

High-performance polymeric materials have been used in computer-assisted design/ computer-assisted milling (CAD/CAM) dental restorative treatments due to their favorable esthetics as well as their mechanical and biological properties. Biocompatible poly-ether-ether-ketone (PEEK) and glass-fiber-reinforced composite techno-polymer (FRC) resins reportedly possess good flexural and shock absorption properties. However, intraoral thermal fluctuations may adversely affect them. This study aimed to investigate the flexural strength and effect of thermal aging on two commercially available high-performance polymers intended for CAD/CAM milled frameworks for definitive restorations. A total of 20 bar specimens were prepared using two CAD/CAM materials (n = 10); PEEK(P) and Bioloren FRC(F). Specimens from each material group were randomly divided into two sub-groups (n = 5): before aging (uP and uF) and after aging, with 10,000 thermocycles (5–55 °C) (aP and aF). All specimens were subjected to a three-point bending test in a universal testing machine. Flexural strength (Fs) values were calculated for all specimens, and their means were statistically analyzed using a t-test, and a general linear model (GLM) repeated measure ANOVA (p &lt; 0.05). There was a statistically significant decrease in the Fs of (F) materials after aging (p = 0.03). (F) specimens exhibited significantly higher Fs than (P) before and after aging (p &lt; 0.001). This type of material had a significant effect on Fs (p &lt; 0.001). Within the limitations of this study, both materials exceeded the ISO recommendations of dental resins for flexural strength. However, FRC materials may benefit CAD/CAM milled long-span fixed partial dentures and implant-supported denture frameworks.

Synthesis of novel fluorobenzene-thiophene hybrid polymer for high-performance electrochromic devices

Electrochromic devices based on high-performance polymer materials with exceptional optical contrast, superior cycling stability, and large coloration efficiency are critical for the advancement of electrochromics, and have the potential to innovate a broad range of applications, including flexible displays and wearable electronics. Here, we design and synthesize three precursors of fluorobenzene-3-methylthiophene D-A-D type polymers through one-step Stille coupling, and then prepare the corresponding polymer films with good electrochemical and electrochromic properties via low-potential electropolymerization at 0.52 V vs Ag/AgCl. Interestingly, such polymers exhibit overall high electrochromic performances during the electrochemical reaction with inversible color changes between yellow and dark blue, including high optical contrast (83% at 1050 nm), fast response time (1.4 s / 0.8 s), and long-term stability (< 2% reduction after 250 cycles). As-fabricated electrochromic devices display excellent cycling stability (< 3% optical contrast degradation after 1,000 cycles) at a low drive voltage (0.8 V). Due to these excellent electrochromic properties, d-A-D type polymers based on fluorobenzene-3-methylthiophene can be further developed for practical applications such as near-infrared camouflage and E-displays.

Synthesis of renewable isosorbide-based polyurethane acrylate resins for UV-cured coating with adjustable properties

Isosorbide (IS) is an ideal bio-based monomer capable of preparing high-performance polymeric materials to substitute petroleum-based materials. Herein, IS is applied as source material to prepare polyurethane acrylate resins (PUA-ISCL2/4/6/8) and ultimately for the preparation of UV-cured coatings. By tuning the amount of ε-caprolactone (CL) in the structure, the resulting coatings exhibit adjustable viscosity, thermal stability and mechanical properties with good hydrophilicity. Double bond conversion of PUA-ISCL8 measured by Photo-DSC with results up to 83 %. More impressively, the prepared UV-cured coatings displayed a suitable pencil hardness of 3H as well as a high glass transition temperature (Tg) of 74 °C. This work proposes to prepare UV-cured coatings with excellent overall performance by regulating the ratio of IS and CL, which has good prospects for practical applications.