Structure Of Resin Research Articles

Retracted: Effect of Free Formaldehyde on Chemical Structure and Thermal Properties of Nano-Titanium Dioxide Resin.

[This retracts the article DOI: 10.1155/2022/7306597.].

A simple fabrication method of passive-matrix organic light-emitting diode display without a photolithography process

A passive-matrix organic light-emitting diode (PMOLED) display was fabricated in a simple self-aligned imprint lithography (SAIL) method without utilizing a photolithography process. This SAIL method is a top-down fabrication process in which all layers constituting the PMOLED are deposited in advance and only the necessary parts are removed by plasma etching to fabricate the display. As an etch mask for sequential plasma etching, a three-dimensional resin structure in which all patterns are pre-aligned was formed using an imprint process. PMOLED fabrication by this SAIL process has the advantage of being very simple as it consists of only one imprint and sequential plasma etching processes. In the PMOLED with 400 pixels fabricated, all pixels operated without deterioration of OLED performance during the fabrication process.

Development of tandem cation exchange chromatography for high purity extracellular vesicle isolation: The effect of ligand steric availability

Purification of extracellular vesicles for research and therapeutic applications requires updated methodology to address the limitations of traditional ultracentrifugation and other size-based separation techniques. Their downfalls include induced extracellular vesicle aggregation, low yields, poor scalability and one-dimensionality of the separation process, as the size or sedimentation speed of extracellular vesicles is often the only selection criterion. Ion exchange chromatography is a promising alternative or supplementary method candidate, as it offers a different approach for extracellular vesicle separation, which is surface charge. For now, mostly anion exchange chromatography has been evaluated for extracellular vesicle purification, as it successfully relies on the strongly negative surface charge of extracellular vesicles. However, as extracellular vesicles are very complex in their structure, also cation exchange chromatography could be applicable, due to individual cationic domains on the extracellular vesicle surface. Here, we compare anion exchange chromatography to different types of cation exchange chromatography for the purification of platelet extracellular vesicle samples also containing plasma-derived impurities. We found that the choice of resin structure used for cation exchange chromatography is critical for binding platelet extracellular vesicles, as a conventional-type cation exchanger was found to only capture and elute less than 20% of extracellular vesicles. With the tentacle-type resin, it was possible to obtain comparable platelet extracellular vesicle yields (over 90%) with cation exchange chromatography compared to anion exchange chromatography, as well as superior purity, especially when it was combined to conventional cation exchange resin.

Simultaneous remediation of Cr and Ni from waste water using efficient Schiff-base resin bis(2-methoxy-1-napthaldehy)-O-phenylene diimine as an adsorbent

In this study, we report the synthesis of a Schiff base, bis(2-methoxy-1-napthaldehy)-o-phenylene diimine (BMNOPhen), and a Schiff-base resin, bis-2-methoxy-1-napthaldehy-o-phenylenediimine (PMBMNOPhen). The materials were characterized via different spectroscopic techniques; CHN analysis, FT-IR, TGA, EDS, SEM, and XRD to analyze the structure and surface morphology and crystallographic evolution of the polymeric resin. The synthesized resin was used for uptake studies with Ni(II) and Cr(VI) ions. The optimum conditions were determined by different parameters used to describe the effects of uptake including initial concentration, temperature, time, and pH through batch adsorption methods. Different functional groups like azomethine, OH, and amine present in the Schiff-based resin structure contain donor N and O atoms which can coordinate cationic metal ions, supported by the active adsorption of chromium(VI) and nickel(II). The isotherm data are informative and useful for calculating and modeling adsorption capacity and exploring the mechanism of removal by the adsorbent Different types of adsorption isotherms like Langmuir, Freundlich, and kinetic studies were used on environmental water samples. The polymeric resin PMBMNOPhen was used for elimination of Cr(VI) and Ni(II) ions in real water samples from different agricultural cities of Sindh (Province of Pakistan) such as Sanghar, Tando-Adam, Kotri, and Jamshoro.

Characterization of Heat-Resistant Insulating Impregnating Varnish Based on Bismaleimide/Diamine Copolymer

With the development of high-voltage electrical equipment towards the direction of higher power density and higher voltage level, it will resulting in the temperature-resistant grade of insulating dip varnish. Bismaleimide (BMI) resin used as the matrix resin of dip varnish solution is widely applied due to its good aging resistance, mechanical properties and dielectric properties. Due to the imide ring structure in BMI resin structure, the bonding energy of chemical bonds in the molecule is higher. The resin reacts less at lower temperatures, resulting in the difficulty of forming and processing. The high crosslinking density of condensates results in unsatisfactory mechanical properties of BMI resin and presents a poor toughness. Therefore, this paper uses Michael addition reaction to prepare branched resin with large free volume from binary amine and BMI resin, and explores various properties of its cured products. The results show that: Using different kinds and different contents of binary amines, its insulation performance was further improved. MT-cured sample had the best comprehensive performance, with a minimum dielectric constant of 3.24. The minimum dielectric loss of BAPP cured sample was 0.00135. The maximum volume resistivity of FDA sample was 2.46×1015 Ω·m and the maximum breakdown field strength of BAPP sample was 29.83 kV/mm; The mechanical properties were significantly improved, and the maximum mechanical strength of the MT samples reached 174.63 MPa.

Investigating the pyrolysis mechanisms of three archetypal ablative resins through pyrolysis experiments and ReaxFF MD simulations

Boron (B-PF), high carbon (HC-PF), and silicone phenolic resins (Si-PF) are typical structures of high-temperature resistant resins with exceptional ablation resistance. Nevertheless, the mechanism of their pyrolytic behavior under ultra-high temperatures remains unclear. Herein, the pyrolysis processes and mechanisms of the three resins are investigated in-depth through experiments and ReaxFF molecular dynamics simulations. According to the experimental results, the final residual carbon rate of the resin shows B-PF > HC-PF > Si-PF. The main products of resin pyrolysis are H2, CH4, CO, small molecular hydrocarbons, and phenolic compounds. The simulation results show that the different types of phenolic resins have consistent pyrolysis products. The main small molecule products are H2, H2O, CO and C2H2. Moreover, these reaction paths are monitored and analyzed. The hydroxyl groups on the naphthalene ring in the high-carbon phenolic make the ring more active and susceptible to decarbonization processes, releasing more carbon monoxide (CO). When silicone resins undergo pyrolysis at high temperatures, the resulting H2O reacts with fragments of silicon-containing molecules to form new silicon oxides upon cooling. The B-O bond in boron phenolic undergoes reorganization upon breakage to form a B-containing five-membered ring, a factor that affects its thermal stability. This research reveals the pyrolytic properties of various phenolic resins and provides a theoretical basis for further research into the pyrolytic behavior of different resins.

Resin structure impacts two-component protein adsorption and separation in anion exchange chromatography

The influence of the resin structure, on the competitive binding and separation of a two-component protein mixture with anion exchange resins is evaluated using conalbumin and green fluorescent protein as a model system. Two macroporous resins, one with large open pores and one with smaller pores, are compared to a resin with grafted polymers. Investigations include measurements of single and two-component isotherms, batch uptake kinetics and two-component column breakthrough. On both macroporous resins, the weaker binding protein, conalbumin, is displaced by the stronger binding green fluorescent protein. For the large pore resin, this results in a pronounced overshoot and efficient separation by frontal chromatography. The polymer-grafted resin exhibits superior capacity and kinetics for one-component adsorption, but is unable to achieve separation due to strongly hindered counter-diffusion. Intermediate separation efficiency is obtained with the smaller pore resin. Confocal laser scanning microscopy provides a mechanistic explanation of the underlying intra-particle diffusional phenomena revealing whether unhindered counter-diffusion of the displaced protein can occur or not. This study demonstrates that the resin's intra-particle structure and its effects on diffusional transport are crucial for an efficient separation process. The novelty of this work lies in its comprehensive nature which includes examples of the three most commonly used resin structures: a small pore agarose matrix, a large-pore polymeric matrix, and a polymer grafted resin. Comparison of the protein adsorption properties of these materials provides valuable clues about advantages and disadvantages of each for anion exchange chromatography applications.

Asphaltene Remediation and Improved Oil Recovery by Advanced Solvent Deasphalting Technology.

Resin molecules play a crucial role in the stability of colloidal asphaltene particles in petroleum reservoirs. De-stabilization of the asphaltene/resin interaction due to changes in thermodynamic parameters can cause asphaltene precipitation, thus leading to petroleum field problems such as decreased in situ permeability, as well as severe plugging problems in production facilities. One remedial technology used in the oil industry involves developing synthetic resins with enhanced chemical potential to increase the stability of asphaltene in the oil phase. However, accurately predicting what synthetic resin structures are compatible with asphaltenes in this context can be difficult and ineffective. Here, we introduce a method that enhances the stability of colloidal asphaltene in petroleum fluid by increasing the concentrations of natural-state oil resins and increases reservoir oil recovery by increasing the oil's aromatic power solvency. The stability of colloidal asphaltene and improvements in oil reservoir recovery were investigated by using an oil prefractionation process and a solvent deasphalting technology based on the residuum oil supercritical extraction process to develop three types of deasphalted oils derived from Kuwait Marrat oil. Using these methods, we found that resin concentration by volume in Marrat oil increased with the removal of more oil fractions. Asphaltene stability in the oil phase was strongly influenced by resin concentration. The deasphalted oils' aromatic power solvency increased the oil reservoir permeability by twofold. No formation damage was observed for all DAO products in core flooding tests.

Influence of topological structure on mechanical property of recyclable bio-based hyperbranched epoxy/carbon fiber fabric composites

Sustainability and high-performance of lightweight epoxy resin/carbon fiber composites are simultaneous challenges for future application in aerospace and wind power. The key to resolve them is designing epoxy resins from non-petroleum-based raw materials, recycling high-value carbon fibers, and improving interfacial interaction. We have increased availably interfacial interaction and performance by changing the topological structure of epoxy resins from linear to hyperbranched shape. The important molecular information about topological microstructure of hyperbranched polymers, such as hydrodynamic radius, mean square radii gyration, shape factor and relaxation rate, etc, are not still obtained to further disclose improving mechanism of interfacial strength. Here, the bio-based degradable hyperbranched epoxy resins (ETFP-n, n = 6, 12, 24) were firstly synthesized by biomass 2,5-furandicarboxylic acid. We have investigated systematically the topological properties of ETFP-n, including molecular size, degree of branching, hydrodynamic radius, mean square radii gyration, shape factor, interdiffusion coefficient, decay rate, conformation, et al, and highlighted the effects of topological structure and rheological property of ETFP-n on the mechanical and interfacial performance of the ETFP-n/carbon fiber composites, and discovered an interfacial improvement mechanism and an intact recycling mechanism of carbon fiber fabric. This work provides a promising approach for designing sustainable high-performance bio-based epoxy resin/carbon fiber composites.

Synthesis of modified poly(ester-amide) and alkyd resins based on phenolic and Schiff base compounds to study their biological and insecticide activity for surface coating applications

PurposeThis paper aims to investigate the prepared modified alkyd and poly(ester-amide) (PEA) resins as antimicrobial and insecticide binders for surface coating applications.Design/methodology/approachSalicylic diethanolamine and 4-(N, N-dimethylamino) benzylidene glutamic acid were prepared and used as new sources of polyol and dibasic acid for PEA and alkyd resins, then confirmed by: acid value, FT-IR and 1H-NMR. The coating performance of the resins was determined using measurements of physico-mechanical properties. The biological and insecticide activities of the prepared resins were investigated.FindingsThe tests carried out revealed that the modified PEA and alkyd enhanced both phyisco-mechanical and chemical properties in addition to the biological and insecticide activities. The results of this paper illustrate that the introduction of salicylic diethanolamine and 4-(N, N-dimethylamino) benzylidene glutamic acid within the resin structure improved the film performance and enhanced the antimicrobial activity performance of PEA and alkyd resins.Research limitations/implicationsThe modified alkyd and PEA organic resins can be used as biocidal binders when incorporated into paint formulations for multiple surface applications, especially those that are exposed to several organisms.Originality/valueModified alkyd and PEA resins based on newly synthesized modifiers have a significant potential to be promising in the production and development of antimicrobial and insecticide paints, allowing them to function to restrict the spread of insects and microbial infection.

Research on the adsorption capacity between asphaltene and resin in asphalt with different aging degree: Experimental study and quantum-mechanical calculation

The regeneration of aged asphalt requires not only softening the already hardened asphalt, but also improving the stability of the micelle structure in the asphalt. In the colloidal hypothesis of asphalt, micelles are assumed to have an asphaltene core and an outer shell composed of resin. Resin molecules can stabilize asphaltene molecules and suspend them in malthene. On this basis, the interaction capacity of asphaltene-resin will directly affect the stability of micelles in malthene. As a result, changes in the ability of asphaltenes and resins to interact with each other during the aging and regeneration of asphalt are gradually receiving a great deal of attention from researchers. However, research in this area is currently limited to molecular dynamics simulations and quantum mechanical calculations and has not yet been investigated using experimental methods. Therefore, in this paper, the changes in the structural stability of micelles during the aging of asphalt are evaluated through experimental studies and quantum mechanical calculations. In subsequent studies, the changes in the structural stability of micelles during the regeneration of ageing asphalt will be further investigated. Firstly, the static adsorption experiment was used to study the adsorption behavior between asphaltene and resin, and the effect of asphalt aging on their adsorption behavior was analyzed by ultraviolet–visible spectroscopy(UV–vis). Secondly, through chemical structure analysis (including GPC, elemental analysis, 1HNMR) and an improved Brown-Ladner(B-L) method, representative molecular models of asphaltene and resin were constructed. The rationality of the molecular models was verified by molecular dynamics simulation(MD). Finally, with the help of Gaussian calculation and Multiwfn analysis, we evaluated the adsorption capacity of asphaltene-resin in virgin and aged asphalt from the molecular level. The adsorption experimental results show that the ability of asphaltene to adsorb resin decreases after asphalt aging, which may reduce the stability of micelles in malthene. The simulation results show that the simulation value and literature value is close, which indicate the new model molecular structure of asphaltene and resin by the B-L method is reasonable. The Gaussian calculation and Multiwfn analysis results show that the asphaltene-resin interaction ability of aged asphalt is lower than that of virgin asphalt. This may be an important factor to reduce the adsorption capacity of asphaltene-resin in aged asphalt. This study provides an in-depth analysis of asphalt aging from the perspective of asphalt micelles and provides new theoretical guidance for the regeneration of aging asphalt.

Diamond-like carbon coating to inner surface of polyurethane tube reduces Staphylococcus aureus bacterial adhesion and biofilm formation

Staphylococcus aureus is one of the main causative bacteria for polyurethane catheter and artificial graft infection. Recently, we developed a unique technique for coating diamond-like carbon (DLC) inside the luminal resin structure of polyurethane tubes. This study aimed to elucidate the infection-preventing effects of diamond-like carbon (DLC) coating on a polyurethane surface against S. aureus. We applied DLC to polyurethane tubes and rolled polyurethane sheets with our newly developed DLC coating technique for resin tubes. The DLC-coated and uncoated polyurethane surfaces were tested in smoothness, hydrophilicity, zeta-potential, and anti-bacterial properties against S. aureus (biofilm formation and bacterial attachment) by contact with bacterial fluids under static and flow conditions. The DLC-coated polyurethane surface was significantly smoother, more hydrophilic, and had a more negative zeta-potential than did the uncoated polyurethane surface. Upon exposure to bacterial fluid under both static and flow conditions, DLC-coated polyurethane exhibited significantly less biofilm formation than uncoated polyurethane, based on absorbance measurements. In addition, the adherence of S. aureus was significantly lower for DLC-coated polyurethane than for uncoated polyurethane under both conditions, based on scanning electron microscopy. These results show that applying DLC coating to the luminal resin of polyurethane tubes may impart antimicrobial effects against S. aureus to implantable medical polyurethane devices, such as vascular grafts and central venous catheters.

A stiffness-tunable soft actuator inspired by helix for medical applications.

This paper introduces the stiffness-tunable soft actuator (STSA), a novel device that combines a silicone body with a thermoplastic resin structure (TPRS). The STSA's design allows for the variable stiffness of soft robots, significantly increasing their potential for use in medical scenarios such as minimally invasive surgeries (MIS). By adjusting the stiffness of the STSA, it is possible to enhance the robot's dexterity and adaptability, making it a promising tool for performing complex tasks in narrow and delicate spaces. The stiffness of the STSA can be modulated by altering the temperature of the TPRS, which has been inspired by the helix and is integrated into the soft actuator to achieve a broad range of stiffness modulation while maintaining flexibility. The STSA has been designed with both diagnostic and therapeutic functions in mind, with the hollow area of the TPRS serving as an instrument channel for delivering surgical instruments. Additionally, the STSA features three uniformly arranged pipelines for actuation by air or tendon, and can be expanded with more functional chambers for endoscopy, illumination, water injection, and other purposes. Experimental results show that the STSA can achieve a maximum 30-fold stiffness tuning, providing a significant improvement in load capacity and stability when compared to pure soft actuators (PSAs). Of particular importance, the STSA is capable of achieving stiffness modulation below 45°C, thereby ensuring a safe entry into the human body and creating an environment conducive to the normal operation of surgical instruments such as endoscope. The experimental findings indicate that the soft actuator with TPRS can achieve a broad range of stiffness modulation while retaining flexibility. Moreover, the STSA can be designed to have a diameter of 8-10mm, which satisfies the diameter requirements of a bronchoscope. Furthermore, the STSA has the potential to be utilized for clamping and ablation in a laparoscopic scenario, thereby demonstrating its potential for clinical use. Overall, these results suggest that the STSA has significant promise for use in medical applications, particularly in the context of minimally invasive surgeries.

Ambient-cured cardanol-derived polyurea coatings for anti-corrosive and anti-bacterial applications

Present work obviates the demand for petroleum products from the coating industry. The current study highlights the potential of bio-based precursor i.e., cardanol for synthesizing solventless coating systems for corrosion inhibition. Initially, prepolymer resin was synthesized from cardanol and was later reacted with toluene diisocyanate (TDI) in different wt% (10, 15, 20, and 25) to obtain an ambient cured polyurea (ACPUrea) resin. The structure of ACPUrea resin was confirmed with the help of FTIR and NMR spectral techniques. The impact of TDI percentage on the coating performance was evaluated in terms of curing behavior, standard phyisco-mechanical characteristics, thermal stability, and chemical resistance as well as wetting behavior. It reveals ACPUrea3 coatings performed better than their other counterparts and 20 wt% TDI is the optimal amount required to fabricate mechanically durable, thermally resistant (>250 °C), hydrophobic (contact angle: 138o), and chemically stable coatings. X-ray diffraction and field emission scanning electron microscopy techniques confirmed the amorphous nature and rough morphology of ACPUrea coating. The bactericidal activities of ACPUrea coatings were also evaluated by standard methods against various gram-positive and gram-negative bacteria, no bacterial growth was observed on and underneath these coatings. Electrochemical impedance spectroscopy suggested outstanding corrosion inhibition efficacy (82 %) of ACPUrea3 coating in harsh corrosive environments. Furthermore, the impedance value observed from the Nyquist plot was found to be steady throughout 15 days of immersion. The overall study emphasizes the utilization of cardanol for synthesizing polyurea coatings with higher thermal stability, excellent corrosion resistance, and strong bactericidal properties.

Effect of weaving parameter and resin structure of lightweight integrated multifunctional composite on thermal protection performance in extreme environment

AbstractThis article reports a novel lightweight integrated multifunctional composite (LIMC) with good thermal ablative and insulating properties for high temperature extreme environment. LIMC, which is an integrated woven carbon fiber preform reinforced phenolic aerogel composites, was prepared using vacuum impregnation and ambient pressure drying. The as‐prepared LIMC consisted of a dense surface layer exposed to environment, and a lightweight insulation zone to manage the heat load. The influences of weaving parameter and resin structure of LIMC on thermal protection and insulting performance were investigated. The results demonstrated that LIMC exhibited excellent ablation and insulation properties, and the weaving parameter and resin structure can affect integrated thermal protection and insulating performance. The 3D orthogonal recession layer with dense aerogels can improve the ablation resistance, while the 2.5D layer‐layer angle‐interlock with light aerogels can increase the insulation behavior of LIMC. The novel LIMC presents wide application prospects in the field of thermal protection and heat insulation.

Effects of the Addition of Amino-Terminated Highly Branched Polyurea on Curing Properties of Phenol-Formaldehyde Resin.

In this work, a highly branched polyurea (HBP-NH2) similar to urea structure was introduced to phenol-formaldehyde (PF) resin to accelerate itscuring speed The results of gel time and bonding strength were combined to obtain a good modified additional stage and amount of HBP-NH2. The relative molar mass changes of HBP-NH2-modified PF resin were investigated by gel permeation chromatography (GPC). The effects of HBP-NH2 on the curing of PF resin were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The effect of HBP-NH2 on the structure of PF resin was also investigated by nuclear magnetic resonance carbon spectroscopy (13C-NMR). The test results show that the gel time of the modified PF resin was reduced by 32% and 51% at 110 °C and 130 °C, respectively. Meanwhile, the addition of HBP-NH2 increased the relative molar mass of PF resin. The bonding strength test showed that the bonding strength of modified PF resin increased by 22% after soaking in boiling water (93 °C ± 2) for 3 h. The DSC and DMA analysis indicated that the curing peak temperature decreased from 137 °C to 102 °C, and the curing rate of the modified PF resin was also faster than that of the pure PF resin. The 13C-NMR results showed that HBP-NH2 in the PF resin reacted to produce a co-condensation structure. Finally, the possible reaction mechanism of HBP-NH2 for the modification of PF resin was given.

Efficient adsorption of alginate oligosaccharides by ion exchange resin based on molecular simulation and experiments

Alginate oligosaccharides (AOS) with low polymerization have gained considerable attention due to their unique physiological activities. However, the lack of understanding regarding the mechanism of action for resin selection and optimization of separation processes has impeded their precise chromatographic separation and large-scale production. Here, the adsorption–desorption characteristics of AOS on the resins with varying solid phase composition, including backbones, functional groups, crosslinking degrees, and counterions resin structures, were analyzed using simulations and experiments. The simulation results revealed that the structural differences of AOS are characterized by their electrostatic potential and lowest unoccupied molecular orbital energy level. Based on molecular simulations, we predicted that the basic anion resin with a styrene backbone would be suitable for AOS separation. Subsequently, we constructed SM-7Cl resin based on the simulation results and performed static adsorption experiments to verify the prediction. SM-7Cl resin demonstrated noteworthy adsorption–desorption performance for AOS, with an adsorption capacity of 471.2 mg/g and a desorption rate of 89.45%. The fitting adsorption isotherm was consistent with the Freundlich model, indicating that the adsorption proceeded spontaneously. The equilibrium times for AOS adsorption on the gel-type resin and the macroporous resin, which both followed a pseudo-second-order kinetic model, were 30 min and 60 min, respectively. This study provides optimized chromatographic media and separation processing that can be implemented for the amplification of chromatographic separation in AOS production.

Elucidating the chemical structures of petroleum resin using solid-state 13C NMR

In this study, a new method to perform the solid-state 13C NMR analysis of oil resin has been proposed and the 3D molecular model of oil resin has been established for the first time. This method is not only suitable for petroleum resin, but also can be used in the structural detection of all colloidal component of fossil fuel. In this research, both liquid- and solid-state 13C NMR based on CP-TOSS/MAS method have been carried out to detect the chemical structural of petroleum resin. Solid-state 13C NMR showed less influence from solvent peaks and achieved a more accurate identification of aromatic carbon and oxygen-containing functional groups than liquid-state 13C NMR, and the FT-IR was used to verify this; thus, it is more suitable for resin structure detection. Based on the results of the two types of NMR, the petroleum resin structure was found to consist of aromatic clusters at the core, with short aliphatic chains and cycloalkanes connected in the periphery. In addition, two new parameters were established to evaluate the length of aliphatic chains (CnR) and oxygen-containing in resins (OINMR: NMR oxygen index of resin). Combined with elemental analysis, the average 3D resin molecular model was established in this research. In general, this study underscored a suitable method for detecting chemical structures in the field of fossil fuel and energy engineering, and successfully introduced solid-state 13C NMR for the analysis of colloidal component of fuel. At the same time, the most stable structural model of petroleum resin in three-dimensional space was established; this provides a basic model for the molecular simulation research of the constituents of petroleum. Considering the important influence of resin on the properties of petroleum, this research has a great significance to migration and exploitation of heavy oil.

Negative-tone photosensitive polyimide with high transparency

Negative-tone photosensitive polyimides (n-PSPI) with high transparency at visible wavelength region (400–700 nm) were prepared by dissolving photosensitive polyimide precursor -poly(amide ester)(PAE) resins, photoinitiator, photocrosslinker and other additives in organic solvents. The PAE resins were synthesized by polycondensation of a fluorinated aromatic diamine with an aromatic diester dichloride or its mixture. The n-PSPI coating solutions showed good photolithographic performance with resolution of 8 µm (via) and 7 µm (line) at 5 µm of the thermally cured film thickness. After thermally cured at 350 °C/1h, the typical PSPI film exhibited excellent thermal properties with Tg of 344 °C and Td5 of 525 °C, respectively. The mechanical properties with elongation at breakage of as high as 42.2% and tensile strength of 133.7 MPa were also measured. Additionally, the thermally cured PSPI films exhibited excellent transparency with UV cuttoff wavelength of 362 nm, transmittance of 90.5% at 450 nm, and 95.5% at 550 nm, as well as yellowness indices of less than 6.55. Furthermore, theoretical simulations were used to prove that trifluoromethyl group in the backbone structure of PSPI precursor resin can effectively improve the transparency of PSPI films.

Evolution of chemical and mechanical properties in two-photon polymerized materials during pyrolysis

Fabrication of three-dimensional (3D) carbon-based structures at micro/nanoscale, mainly by pyrolysis of photocured resins, has recently drawn attention in battery development, material engineering, and catalysts. Upon pyrolysis, photocured 3D polymer structures undergo thermal decomposition and eventually carbonize while maintaining their 3D features. Herein, we systemically investigate the physical and chemical reactions that occur during the pyrolysis of methacrylate-based resin structures, yielding fundamental knowledge and an improved understanding of the pyrolysis processes. Based on our results, the pyrolysis process can be divided into three stages: monomer evaporation, chemical decomposition, and carbonization, in which the volume shrinkage mainly occurs in the first and third stages. The three stages have different effects on the mechanical properties of the pyrolyzed structures, with monomer evaporation and carbonization enhancing the Young's modulus while decomposition reduces the Young's modulus. Additionally, the surface smoothness of the photocured structures can be improved during pyrolysis due to the shrinkage of the polymer resins, which provides a potential approach to generating ultrasmooth carbon surfaces.