High Glass Transition Temperature Research Articles

Highly Stable Binary Cross‐Linkable Organic Nonlinear Optical Materials Using Different Acceptors Based on Huisgen Cycloaddition Reaction

Comprehensive SummaryHow to obtain organic electro‐optic materials with large electro‐optic coefficients, high glass transition temperature, and good optical transparency remains a challenge in this field. To solve this problem, we introduce groups that can undergo Huisgen cycloaddition reactions into the donor and electron bridge of chromophores with large hyperpolarizability using tetrahydroquinoline as the donor. Binary cross‐linkable chromophores TLD1‐2 with CF3‐TCF as the acceptor and chromophores TLD3‐4 with 5Fph‐TCF as the acceptor were synthesized. After poling and crosslinking, the Tg of TLD1/TLD2 and TLD3/TLD4 were raised to 152 and 174 °C, respectively. The electro‐optical coefficients of chromophores TLD1/TLD2 and TLD3/TLD4 were as high as 312 pm/V and 287 pm/V, respectively. The long‐term alignment stability test showed that after being left at 85 °C for 500 h, the cross‐linked film TLD3/TLD4 can still maintain more than 98% of the original electro‐optical coefficient value, which is higher than that of TLD1/TLD2 (93%). The chromophore TLD3‐4 exhibited much blue‐shifted maximum absorption wavelengths (~40 nm) compared to TLD1‐2 which was beneficial for reducing optical loss in the device. The combination of high electro‐optic coefficient, strong stability, and excellent optical transparency makes the TLD series of binary cross‐linked materials very promising for practical high‐performance electro‐optic devices.

Stable energy storage performance of introduced PI-PESU dielectric composite serving at the high electric and thermal fields with the designed layer structure

Excellent energy storage performance of dielectric capacitor is critical in modern electronic devices and power systems. However, the key component of dielectric composite may fail to function properly under severe service conditions, such as elevated temperature and great applied electric field. Here, the linear dielectrics of PI and PESU with high glass transition temperature (Tg) were proposed to improve the energy storage performance of composite, which hold the weakened carrier migration. The large band-gap of PESU and tight molecular chain of PI are beneficial for reducing leakage current density of composite, enhancing inter-molecular stability over a wide temperature and electric field range. Finally, the energy storage performance is improved by constructing a multi-layer structure with alternating outer layers. For instance, the discharge energy density (Ue) of 0.4PI-0.6PESU composite reaches 6.38 J/cm3 at 700 kV/mm and 80 °C. Significantly, the Ue of multi-layer 2/1/PVDF/1/2 composite is increased by 92.36 % at 80 °C and 400 kV/mm (from 2.88 J/cm3 to 5.54 J/cm3), and the efficiency (η) of it keeps at 68.5 %. Meanwhile, it owns a good cycle stability after 50,000 cycles with η > 90 %. This work provides a new direction of developing dielectric composite serving in severe service conditions for capacitors.

Novel bio-based propylene-derived phthalonitrile compounds: Synthesis, curing behavior and thermal properties

Bio-based bisphenol compounds were prepared using eugenol from biomass as the initial raw material. A reaction of nucleophilic substitution takes place with 4-nitrophthalonitrile in an environmentally friendly solvent to produce bio-based propenyl-derived phthalonitrile monomers. The effective preparation of compounds was proven using hydrogen and carbon nuclear magnetic resonance and fourier transform infrared spectroscopy (FT-IR). By employing the process of free radical catalysis, it is possible to directly cure the novel phthalonitrile monomers without the need for a specific small molecule curing agent. The cured resin was reported to have high glass transition temperature, good thermal stability, and processing properties by FT-IR, differential scanning calorimetry, thermogravimetric analyzer, dynamic mechanical analyzer, and rheometer techniques. The flexural test and scanning electron microscopy results show that both resins have a consistent, flawless structure and improved mechanical properties. Eugenol is derived from sustainable biomass, offering an environmentally friendly approach to utilizing biological monophenols effectively. It provides the benefits of carbon reduction and renewability, making it a valuable and eco-conscious resource.

Oligomerized Acceptors with High Efficiency and Superior Stability in Organic Solar Cells.

Oligomerized small molecular acceptors (OSMAs) have rapidly become a research hotspot in the field of organic solar cells due to their advantages of effective combination with definite structure of small molecules and high viscosity and glass transition temperature of polymers. From this perspective, we classify and summarize the representative OSMAs from the three binding sites of end, core, and wing, and we summarize the exploration of new synthesis methods to improve the plights, such as low synthesis yield and difficult purification. Finally, the existing challenges and future research directions are concluded and prospected.

Control over phase structures’ evolution within the novel organic–inorganic hybrid system for achieving a comprehensive thermal, mechanical, and dielectric properties

Significant challenges persist in developing high-performance, wave-transparent capable of operating above 500 ℃ using organic–inorganic hybrid materials. This study introduced a novel, highly reactive terminal carborane monomer, 4-(3-carborylphenyl) phthalonitrile (CB-Ph), to create a cross-linked network structure and inorganic phase. By integrating this with the conventional high-performance poly (phthalazine ether nitrate ketone) (PPENK), a novel organic–inorganic hybrid system was successfully constructed. Simultaneously, the modifications in the inorganic layer and phase structure of the material with increasing CB-Ph content were examined through nanoindentation and SEM analysis systems, establishing a structural foundation for optimizing the balance between thermal resistance, mechanical strength, and dielectric properties (balance of T-M−D). The thermal performance testing results indicates that the hybrid materials achieved high glass transition temperatures (Tg exceeding 500 ℃). This enhancement is attributable to the synergistic effects of cyanide side group micro-crosslinking and the phthalonitrile crosslinking network, which collectively restricted the movement of chain segments. The P-CB50 resin (PPENK+50 wt% CB-Ph), with its distinctive transition phase structure, boasts the most outstanding comprehensive performance. In terms of thermal stability, it not only features a Tg surpassing 500 ℃ In terms of thermal stability, it not only has a Tg exceeding 500 °C, but also loses only 5 % weight at 599.3° C in a nitrogen atmosphere (Td5%–N2 = 599.3 °C). Mechanical testing reveals that the flexural strength of the P-CB50 composite reaches an impressive 384.3 MPa, while the impact strength attains a significant 109.4 KJ/m2. Even at temperatures as high as 500 ℃, the dielectric constant of the P-CB50 composite material remains below 4, underscoring its superior high temperature wave-transparent properties. These results have firmly established a correlation between the phase structure of the hybrid system and the comprehensive performance of T-M−D, thereby laying a solid foundation for the development of high-temperature resistant and wave-transparent materials with enhanced overall performance.

Polyfluoride Acceptor with Limited Molecular Diffusion Enables Efficient and Stable Ternary Organic Solar Cells.

Due to the slow diffusion of photovoltaic molecules, in particular, small-molecule acceptors (SMAs), under light and heating, the morphology of the active layer in organic solar cells (OSCs) prefers to deviate from the favorably metastable status, leading to the challenge of stability during long-term operation. Employing materials with a high glass transition temperature (Tg) as the third component to suppress molecular diffusion is an efficient method to achieve the balance of efficiency and stability of OSCs. Herein, a dimerized small-molecule acceptor denoted as F6D is synthesized by introducing a polyfluoride moiety as the linker to enhance the Tg. Benefitting from a rational molecular design, F6D not only exhibits a higher Tg, complementary absorption, and cascade energy levels with the host materials of the polymer donor PM6 and the SMA Y6 but also has excellent miscibility and multiple intermolecular interactions with Y6. As a result, a champion power conversion efficiency of 17.52% is achieved in the optimal PM6:Y6:F6D-based device. More importantly, the ternary device exhibits superior stability under continuous heating and lighting compared with the binary device.

Aromatic Polymethacrylates from Lignin-Based Feedstock: Synthesis, Thermal Properties, Life-Cycle Assessment and Toxicity.

There is currently a great need for rigid, high-performance and processable bio-based polymers and plastics as alternatives to the fossil-based materials used today. Here, we report on the straightforward synthesis and polymerization of lignin-derived methacrylate monomers based on the methyl esters of syringic, vanillic, and 4-hydroxybenzoic acid, respectively. The corresponding homopolymethacrylates exhibit high glass transition temperatures (Tgs) at 106, 128, and 197°C, respectively. Rheological properties and thermal stability up to at least 277 °C indicate that these polymers are melt-processable. In addition, copolymers with methyl methacrylate are prepared to further vary and tune the polymer properties. An integrated ex-ante and prospective life-cycle assessment of key environmental impact parameters indicates similar or only slightly higher values compared to well-established fossil-based methyl methacrylate. Moreover, the toxicity towards human HeLa cell lines compares well with that of poly(methyl methacrylate). Hence, the potential availability of lignin-derived acids, combined with the straightforward and potentially upscalable monomer synthesis, make these rigid polymers appealing alternatives towards bio-based high-Tgthermoplastic materials with low toxicity.

Preparation and characterization of hydroxyethyl cellulose/nanolignin composite films

Hydroxyethyl cellulose/nanolignin composite films were prepared and characterized. The composite films were produced via casting of synthesized nanolignin added to hydroxyethyl cellulose at different concentrations (2.5%, 5%, 10%, and 20% by mass). A control film without nanolignin was also prepared for comparison. The thermal properties of the composite films were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), while the mechanical properties were determined by tensile testing and the surface properties were determined by water contact angle measurements. In addition, the morphologies of the samples were examined by scanning electron microscopy (SEM). It was observed that with the addition of nano lignin, the glass transition temperature of the composite films increased from 109 °C to 262 °C; the elongation at break increased from 19% to 51%; and the contact angles increased from 53 °C to 73 °C. The results showed that the presence of nanolignin produced materials being more flexible and more hydrophobic with higher glass transition temperatures.

Solubility Change Behavior of Fluoroalkyl Ether-Tagged Dendritic Hexaphenol under Extreme UV Exposure.

This study focuses on the discovery of a single-component molecular resist for extreme ultraviolet (EUV) lithography by employing the ionizing radiation-induced decomposition of carbon-fluorine chemical bonds. The target material, DHP-L6, was synthesized by bonding perfluoroalkyl ether moieties to amorphous dendritic hexaphenol (DHP) with a high glass transition temperature. Upon exposure to EUV and electron beam irradiation, DHP-L6 films exhibited a decreasing solubility in fluorous developer media, resulting in negative-tone images. The underlying chemical mechanisms were elucidated by Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy, and nanoindentation experiments. These analyses highlighted the possible electron-induced decomposition of C-F bonds in DHP-L6, leading to molecular network formation via recombination of the resulting C-centered radicals. Subsequent high-resolution lithographic patterning under EUV irradiation showed that DHP-L6 could create stencil patterns with a line width of 26 nm at an exposure dose of 110 mJ cm-2. These results confirm that single-component small molecular compounds with fluoroalkyl moieties can be employed as patterning materials under ionizing radiation. Nonetheless, additional research is required to reduce the relatively high exposure energy for high-resolution patterning and to enhance the line-edge roughness of the produced stencil.

Enhancing mechanical and thermal properties of blends with novel phenylethynyl-terminated siloxane-containing ortho-hydroxy polyimide

A novel phenylethynyl-terminated siloxane-containing ortho-hydroxy polyimide (O-SPI) was synthesized and physically blended with thermoplastic polyimide (PI) to enhance both the thermal and mechanical properties of polyimide, addressing the growing demand for high-performance materials in harsh environments. The blend underwent conversion to semi-Interpenetrating Polymer Networks ( semi-IPNs) and benzoxazole structures through thermal curing of reactive phenylethynyl groups and thermal rearrangement of ortho-hydroxy imide units. The trends in thermal and mechanical properties were investigated in relation to the chemical structures and varying mass fraction of O-SPI. The covalent incorporation of semi-IPNs and rigid benzoxazole structures restrict segmental motion while the backbone linkage confers the toughness of the blends. These synergistic effects insure the cured blends with high glass transition temperatures (472.51°C) and tensile strength (117.81 MPa) simultaneously, demonstrating their potential for applications in challenging conditions.

Data-Driven Design of Novel Polymer Excipients for Pharmaceutical Amorphous Solid Dispersions.

About 90% of active pharmaceutical ingredients (APIs) in the oral drug delivery system pipeline have poor aqueous solubility and low bioavailability. To address this problem, amorphous solid dispersions (ASDs) embed hydrophobic APIs within polymer excipients to prevent drug crystallization, improve solubility, and increase bioavailability. There are a limited number of commercial polymer excipients, and the structure-function relationships which lead to successful ASD formulations are not well-documented. There are, however, certain solid-state ASD characteristics that inform ASD performance. One characteristic shared by successful ASDs is a high glass transition temperature (Tg), which correlates with higher shelf stability and decreased drug crystallization. We aim to identify how polymer features such as side chain geometry, backbone methylation, and hydrophilic-lipophilic balance impact Tg to design copolymers capable of forming high-Tg ASDs. We tested a library of 50 ASD formulations (18 previously studied and 32 newly synthesized) of the model drug probucol with copolymers synthesized through automated photoinduced electron/energy transfer-reversible addition-fragmentation chain-transfer (PET-RAFT) polymerization. A machine learning (ML) algorithm was trained on the Tg data to identify the major factors influencing Tg, including backbone methylation and nonlinear side chain geometry. In both polymer alone and probucol-loaded ASDs, a Random Forest Regressor captured structure-function trends in the data set and accurately predicted Tg with an average R2 > 0.83 across a 10-fold cross validation. This ML model will be used to predict novel copolymers to design ASDs with high Tg, a crucial factor in predicting ASD success.

A bio-based low dielectric polymer at high frequency derived from paeonol

A fluorinated monomer with crosslinkable benzocyclobutene groups has been successfully synthesized starting from bio-based paeonol through the Suzuki and Grignard reaction. Treating this monomer at high temperature forms a cross-linked resin (cured PFB), which exhibits high glass transition temperature (Tg) of 439 °C, low coefficient of thermal expansion (CTE) of 87.4 ppm/°C, low dielectric constant (Dk) of 2.62, and low dielectric loss (Df) of 8.45 × 10-4 at a frequency of 10 GHz. In particular, cured PFB displays low water uptake of 0.1% even immersing it in boiling water for 96 h. These results demonstrate that the fluorinated bio-based monomer is a suitable precursor for the preparation of the low-dielectric packaging materials used in the microelectronic industry. Especially, this contribution provides a new way for the conversion of bio-based paeonol into the high-performance materials.

Functional dry powders of connexin-containing extracellular vesicles

Extracellular vesicles (EVs) have emerged as a promising drug delivery system. Connectosomes are a specialized type of EVs that contain connexins in their membranes. Connexin is a surface transmembrane protein that forms connexin hemichannels. When a connexin hemichannel on a connectosome docks with another connexin hemichannel of a target cell, they form a gap junction that allows direct intracellular delivery of therapeutic cargos from within the connectosome to the cytoplasm of the recipient cell. In the present study, we tested the feasibility of converting connectosomes into dry powders by (thin-film) freeze-drying to enable their potential storage in temperatures higher than the recommended −80 °C, while maintaining their activity. Connectosomes were isolated from a genetically engineered HeLa cell line that overexpressing connexin-43 subunit protein tagged with red fluorescence protein. To facilitate the testing of the function of the connectosomes, they were loaded with calcein green dye. Calcein green-loaded connectosomes were thin-film freeze-dried with trehalose alone or trehalose and a polyvinylpyrrolidone polymer as lyoprotectant(s) to produce amorphous powders with high glass transition temperatures (>100 °C). Thin-film freeze-drying did not significantly change the morphology and structure of the connectosomes, nor their particle size distribution. Based on data from confocal microscopy, flow cytometry, and fluorescence spectrometry, the connexin hemichannels in the connectosomes reconstituted from the thin-film freeze-dried powder remained functional, allowing the passage of calcein green through the hemichannels and the release of the calcein green from the connectosomes when the channels were opened by chelating calcium in the reconstituted medium. The function of connectosomes was assessed after one month storage at different temperatures. The connexin hemichannels in connectosomes in liquid lost their function when stored at −19.5 ± 2.2 °C or 6.0 ± 0.5 °C for a month, while those in dry powder form remained functional under the same storage conditions. Finally, using doxorubicin-loaded connectosomes, we showed that the connectosomes reconstituted from thin-film freeze-dried powder remained pharmacologically active. These findings demonstrate that (thin-film) freeze-drying represents a viable method to prepare stable and functional powders of EVs that contain connexins in their membranes.

Catalyst-free gallic acid-based epoxy vitrimers with reprocessability and high glass transition temperature

General approaches for preparing epoxy vitrimers required lots of catalysts to accelerate transesterification to form the cross-linked network and the residual catalyst not only resulted in toxicity but also poor compatibility with other components. Herein, a green and facile strategy for preparing gallic acid epoxy resin (GA-EP) was developed under catalyst-free condition using renewable gallic acid, xylitol and hexahydro 4-methylphthalic anhydride (MHHPA) as feedstocks. The results indicated that the bio-based epoxy vitrimer had higher glass transition temperature (122 °C), satisfactory mechanical, thermal and degradation properties compared to neat Bisphenol A-based epoxy vitrimer. Furthermore, recycled GA-EP was ground into powder and added to the fresh resin to investigate its reusability. Compared to the original, the recycled epoxy vitrimer system demonstrated comparable performance, except for minor reductions in glass transition temperature (Tg) and modulus, likely stemming from the inherent inhomogeneity of the reprocessed material. This work provides a new approach to the production of high Tg bio-based epoxy vitrimers without adding any catalyst.

Multiscale Modeling of Vinyl-Addition Polynorbornenes: The Effect of Stereochemistry.

Vinyl-addition polynorbornenes are candidates for designing high-performance polymers due to unique characteristics, which include a high glass transition temperature associated with a rigid backbone. Recent studies have established that the processability and properties of these polymers can be fine-tuned by using targeted substitutions. However, synthesis with different catalysts results in materials with distinct properties, potentially due to the presence of various stereoisomers that are difficult to quantify experimentally. Herein, we develop all-atom models of polynorbornene oligomers based on classical force fields and density functional theory. To establish the relationship between chemical architecture, chain conformations, and melt structure, we perform detailed molecular dynamics simulations with the fine-tuned atomistic force field and propose simpler coarse-grained descriptions to address the high molecular weight limit. All-atom simulations of oligomers suggest high glass transition temperatures in the range of 550-600 K. In the melt state (800 K), meso chains form highly rigid extended coils (C∞≈11) with amorphous structural characteristics similar to the X-ray diffraction data observed in the literature. In contrast, simulations with racemo chains predict highly helical tubular chain conformations that could promote assembly into crystalline structures.

Amorphous Solid Dispersions: Implication of Method of Preparation and Physicochemical Properties of API and Excipients.

The present study investigated the effect of different polymers and manufacturing methods (hot melt extrusion, HME, and spray drying, SD) on the solid state, stability and pharmaceutical performance of amorphous solid dispersions. In the present manuscript, a combination of different binary amorphous solid dispersions containing 20% and 30% of drug loadings were prepared using SD and HME. The developed solid-state properties of the dispersions were evaluated using small- and wide-angle X-ray scattering (WAXS) and modulated differential scanning calorimetry (mDSC). The molecular interaction between the active pharmaceutical ingredients (APIs) and polymers were investigated via infrared (IR) and Raman spectroscopy. The in vitro release profile of the solid dispersions was also evaluated to compare the rate and extend of drug dissolution as a function of method of preparation. Thereafter, the effect of accelerated stability conditions on the physicochemical properties of the solid dispersions were also evaluated. The results demonstrated higher stability of Soluplus® (SOL) polymer-based solid dispersions as compared to hydroxypropyl methylcellulose (HPMC)-based solid dispersions. Moreover, the stability of the solid dispersions was found to be higher in the case of API having high glass transition temperature (Tg) and demonstrated higher interaction with the polymeric groups. Interestingly, the stability of the melt-extruded dispersions was found to be slightly higher as compared to the SD formulations. However, the down-processing of melt-extruded strands plays critical role in inducing the API crystal nuclei formation. In summary, the findings strongly indicate that the particulate properties significantly influence the performance of the product.

Polymeric Fibers with High Strength and High Toughness at Extreme Temperatures.

Developing strong and simultaneously tough polymeric materials with excellent thermal stability and mechanical performance even under extreme temperatures is truly a challenge. In a disruptive progress, continuous polymeric yarns are developed with a combination of high tensile strength of (1145 ± 44) MPa and ultrahigh toughness of (350 ± 24) J g-1 and high thermomechanical properties from -196 to 200°C. The comprehensive thermomechanical performance of this yarn surpasses that of previously developed polymeric materials and dragline spider silks. The results demonstrate that the molecular structure of polyimide (PI) with the incorporation of flexible-rigid macromolecular, hierarchically spiral-oriented fibers, and high glass transition temperature (248°C) are keys for the yarn's notable comprehensive performance in thermomechanical properties. The materials are ideal for technical components exposed to high thermomechanical loadings, such as those encountered in spacecraft or automotive engineering for safety-critical applications.

6-Carboxycellulose Acetate Butyrate: Effectiveness as an Amorphous Solid Dispersion Polymer.

Amorphous solid dispersion (ASD) in a polymer matrix is a powerful method for enhancing the solubility and bioavailability of otherwise crystalline, poorly water-soluble drugs. 6-Carboxycellulose acetate butyrate (CCAB) is a relatively new commercial cellulose derivative that was introduced for use in waterborne coating applications. As CCAB is an amphiphilic, carboxyl-containing, high glass transition temperature (Tg) polymer, characteristics essential to excellent ASD polymer performance, we chose to explore its ASD potential. Structurally diverse drugs quercetin, ibuprofen, ritonavir, loratadine, and clarithromycin were dispersed in CCAB matrices. We evaluated the ability of CCAB to create ASDs with these drugs and its ability to provide solubility enhancement and effective drug release. CCAB/drug dispersions prepared by spray drying were amorphous up to 25 wt % drug, with loratadine remaining amorphous up to 50% drug. CCAB formulations with 10% drug proved effective at providing in vitro solubility enhancement for the crystalline flavonoid drug quercetin as well as ritonavir, but not for the more soluble APIs ibuprofen and clarithromycin and the more hydrophobic loratadine. CCAB did provide slow and controlled release of ibuprofen, offering a simple and promising Long-duration ibuprofen formulation. Formulation with clarithromycin showed the ability of the polymer to protect against degradation of the drug at stomach pH. Furthermore, CCAB ASDs with both loratadine and ibuprofen could be improved by the addition of the water-soluble polymer poly(vinylpyrrolidone) (PVP), with which CCAB shows good miscibility. CCAB provided solubility enhancement in some cases, and the slower drug release exhibited by CCAB, especially in the stomach, could be especially beneficial, for example, in formulations containing known stomach irritants like ibuprofen.

High Glass Transition Temperature Fluorinated Polymers Based on Transfer Learning with Small Experimental Data

High Glass Transition Temperature Fluorinated Polymers Based on Transfer Learning with Small Experimental Data

Thermally Stable and Transparent Polyimide Derived from Side-Group-Regulated Spirobifluorene Unit for Substrate Application.

Advancements in flexible electronic technology, especially the progress in foldable displays and under-display cameras (UDC), have created an urgent demand for high-performance colorless polyimide (CPI). However, current CPIs lack sufficient heat resistance for substrate applications. In this work, four kinds of rigid spirobifluorene diamines are designed, and the corresponding polyimides are prepared by their condensation with 5,5'-(perfluoropropane-2,2-diyl) bis(isobenzofuran-1,3-dione) (6FDA) or 9,9-bis(3,4-dicarboxyphenyl) fluorene dianhydride (BPAF). The rigid and conjugated spirobifluorene units endow the polyimides with higher glass transition temperature(Tg) ranging from 356 to 468 °C. Their optical properties are regulated by small side groups and spirobifluorene structure with a periodically twisted molecular conformation. Consequently, a series of CPIs with an average transmittance ranging from 75% to 88% and a yellowness index (YI) as low as 2.48 are obtained. Among these, 27SPFTFA-BPAF presents excellent comprehensive performance, with a Tg of 422 °C, a 5wt.% loss temperature (Td5) of 562 °C, a YI of 3.53, and a tensile strength (δmax) of 140MPa, respectively. The mechanism underlying the structure-property relationship is investigated by experimental comparison and theoretical calculation, and the proposed method provides a pathway for designing highly rigid conjugated CPIs with excellent thermal stability and transparency for photoelectric engineering.