Molecular Rigidity Research Articles

Side-chain cyclization enhancing molecular rigidity and π-π stacking yields as-cast binary organic solar cells with 19.1% efficiency

Side-chain cyclization enhancing molecular rigidity and π-π stacking yields as-cast binary organic solar cells with 19.1% efficiency

A butterfly shape acceptor with rigid skeleton and unique assembly enables both efficient organic photovoltaics and high-speed organic photodetectors

Abstract It remains challenging to design efficient bifunctional semiconductor materials in organic photovoltaic and photodetector devices. Here, we report a butterfly-shaped molecule, named WD-6, which exhibits low energy disorder and small reorganization energy due to its enhanced molecular rigidity and unique assembly with strong intermolecular interaction. The binary photovoltaic device based on PM6:WD-6 achieved an efficiency of 18.41%. Notably, an efficiency of 19.42% was achieved for the ternary device based PM6:BTP-eC9:WD-6. Moreover, the photodetection device based on WD-6 demonstrated an ultrafast response speed (205 ns response time at λ of 820 nm) and a high cutoff frequency of -3 dB (2.45 MHz), surpassing the values of most commercial Si photodiodes. Based on these findings, we show-cased an application of the WD-6-based photodetection device in high-speed optical communication. These results offer valuable insights into the design of organic semiconductor materials capable of simultaneously exhibiting high photovoltaic and photo detective performance.

Optimization across-the-Board: Centro-Arylated Push-Pull Tetraene Chromophores and Guest-Host Polymers for Electro-Optics.

The research and development of push-pull tetraene chromophores (PPT-phores) have contributed greatly to the field of organic electro-optic (EO) materials and devices since the inauguration of CLD-1 in 2001. This study is thus a systematic contribution to synthesize and characterize a series of centro-arylated PPT-phores based on strong electron-donating tetrahydroquinolinyl groups and variable strong electron-accepting tricyanofuran derivatives. In particular, we report the crystallographic data to show various packing modes of these PPT-phores with detailed information about bond length alternation and intermolecular interactions, the optical absorption edges of guest-host polymers by the Tauc model, and the anisotropy and dispersion of Pockels tensors for the poled polymers by attenuated total reflection spectroscopy. Such analyses have not been addressed to any significant extent previously and are fundamentally important to the future development of PPT-phore-based EO materials and devices. The poled films of several centro-arylated PPT-phores in polycarbonates exhibited large EO activities, excellent thermal stability, and tunable optical transparency at the telecom O- and C-band. The study demonstrates the effectiveness of π-bridge centro-arylation enabled by molecular shape modification and rigidity enhancement, over the relatively flexible and labile thioether or alkoxy groups, in rational design of hyperpolarizable PPT-phores for high-performance EO polymers.

Promoting WLED‐Excited High Temperature Long Afterglow by Orthogonally Anchoring Chromophores into 0D Metal‐Organic Cages

AbstractAfterglow materials have garnered significant interest due to distinct photophysical characteristics. However, it is still difficult to achieve long afterglow phosphorescence from organic molecules due to aggregation‐caused quenching (ACQ) and energy dissipation. In addition, most materials reported so far have long afterglow emission only at room or even low temperatures, and mainly use UV light as an excitation source. In this work, we report a strategy to achieve high temperature long afterglow emission through the assembly of isolated 0D metal‐organic cages (MOCs). In which, both ACQ and phosphorescence quenching effects are effectively mitigated by altering the stacking mode of organic chromophores through orthogonally anchoring into the edges of cubic MOCs. Furthermore, improvement in molecular rigidity, promotion of spin‐orbit coupling and broadening of the absorption range are achieved through the MOC‐engineering strategy. As a result, we successfully synthesized MOCs that can produce afterglow emission even after excitation by WLEDs at high temperatures (380 K). Moreover, the MOCs are capable of generating afterglow emissions when excited by mobile phone flashlight at room temperature. Given these features, the potential applications of MOCs in the visual identification of explosives, information encryption and multicolor display are explored.

Smoothening Perfluoroalkylated Surfaces: Liquid‐Like Despite Molecular Rigidity?

AbstractThe rational design of surfaces at the molecular level is essential toward realizing many engineering applications. However, molecular‐scale defects affect processes such as triboelectrification, scaling, and condensation. These defects are often detectable via contact angle hysteresis (CAH) measurements. Liquid‐like surfaces exhibit extremely low CAH (≤5°) and rely on the use of highly flexible molecular species such as long‐chain alkyls or siloxanes. Their low glass transition temperatures lead to the so‐termed self‐smoothing behavior, reducing sensitivity to defects formed during fabrication. However, utilizing rigid molecular species such as perfluoroalkyl chains often results in higher hysteresis (10° to 60°) as defects are not self‐smoothed after fabrication. Consequently, state‐of‐the‐art perfluoroalkylated surfaces often show sub‐optimal interfacial properties. Here, a customizable chemical vapor deposition process creates molecularly‐thick, low‐defect surfaces from trichloro(1H,1H,2H,2H‐perfluorooctyl)silane. By implementing moisture‐exposure controls, highly homogenous surfaces with root‐mean‐square roughness below 1 nm are fabricated. CAH is achieved down to ≈4° (average: 6°), surpassing the state‐of‐the‐art by ≈5°. Reduction of CAH (26° to 6°) results in condensation suppression, decreasing surface droplet density by one order and surface droplet coverage by 40%. This work guides the synthesis of high‐quality surfaces from tri‐functional perfluoroalkylsilanes with liquid‐like properties despite their molecular rigidity.

Promoting WLED-Excited High Temperature Long Afterglow by Orthogonally Anchoring Chromophores into 0D Metal-Organic Cages.

Afterglow materials have garnered significant interest due to distinct photophysical characteristics. However, it is still difficult to achieve long afterglow phosphorescence from organic molecules due to aggregation-caused quenching (ACQ) and energy dissipation. In addition, most materials reported so far have long afterglow emission only at room or even low temperatures, and mainly use UV light as an excitation source. In this work, we report a strategy to achieve high temperature long afterglow emission through the assembly of isolated 0D metal-organic cages (MOCs). In which, both ACQ and phosphorescence quenching effects are effectively mitigated by altering the stacking mode of organic chromophores through orthogonally anchoring into the edges of cubic MOCs. Furthermore, improvement in molecular rigidity, promotion of spin-orbit coupling and broadening of the absorption range are achieved through the MOC- engineering strategy. As a result, we successfully synthesized MOCs that can produce afterglow emission even after excitation by WLEDs at high temperatures (380 K). Moreover, the MOCs are capable of generating afterglow emissions when excited by mobile phone flashlight at room temperature. Given these features, the potential applications of MOCs in the visual identification of explosives, information encryption and multicolor display are explored.

New AIEgens based on thieno[2,3-d]pyrimidine derivatives: Synthesis, DFT calculations, and molecular docking

In this paper, new thieno[2,3-d]pyrimidine analogs have been synthesized and characterized through different spectroscopic techniques. The photophysical properties of the molecules (7b-7f) and the quantum chemical calculations have been investigated. These molecules exhibited aggregation-induced emission behavior and showed efficient emission in both solid and solution states. A shift toward shorter wavelengths (hypsochromic shift) was observed when transitioning from the solution to the solid state, which could be explained by photoinduced intramolecular charge transfer (ICT) processes. DFT calculations confirmed that the diverse behavior of the thieno[2,3-d]pyrimidine analogs could be attributed to variations in molecular packing and rigidity. This study illustrates how luminophores aggregation can occur without significantly impacting the excited state, emphasizing the unconventional behavior resulting from minor alterations in terminal substituents. These findings hold implications for the advancement of luminescent materials. Additionally, theoretical calculations were conducted to compare the excitations and emissions of the new AIEgens with practical observations. Furthermore, a molecular docking study of the five AIEgens suggested their potential utility as anticancer drugs. Compound 7c exhibited a high affinity for human cyclin-dependent kinase 2 (CDK-2) protein, with a binding energy of 9.6 kcal/mol, indicating its potential as an inhibitor for this specific protein.

An efficient thermally activated delayed fluorophore featuring an oxygen-locked azaryl ketone acceptor

Thermally activated delayed fluorescence (TADF) dyes are promising for applications like bioimaging, sensing, and optoelectronic devices due to their efficient exciton utilization without noble metals, making them ideal for organic light-emitting diodes (OLEDs). In this contribution, we introduce a new TADF emitter, 3-(9,9-dimethylacridin-10(9H)-yl)-12H-chromeno[2,3-b]quinolin-12-one (CQLO-DMAC), which incorporates an intramolecular oxygen-locked azaryl ketone acceptor, CQLO. This design enhances molecular rigidity and electron-accepting strength. The CQLO-DMAC compound, featuring a bulky donor, shows significant intramolecular charge transfer and TADF emission. Comprehensive analyses, including spectroscopic studies and theoretical calculations, reveal high luminescence efficiency and reduced non-radiative losses. Utilizing CQLO-DMAC in OLEDs, we achieved a green-yellow emission peak at 548 nm and a maximum external quantum efficiency of 17.4%. The findings highlight the potential of CQLQ as a highly effective acceptor in designing of TADF electroluminescent dyes.

Protein Corona Formation on Cadmium-Bearing Nanoparticles: Important Role of Facet-Dependent Binding of Cysteine-Rich Proteins.

Cadmium-bearing nanoparticles, such as nanoparticulate cadmium selenide (CdSe) and cadmium sulfide (CdS), widely exist in the environment and originate from both natural and anthropogenic sources. Risk assessment of these nanoparticles cannot be accurate without taking into account the properties of the protein corona that is acquired by the nanoparticles upon biouptake. Here, we show that the compositions of the protein corona on CdSe/CdS nanoparticles are regulated collectively by the surface atomic arrangement of the nanoparticles and the abundance and distribution of cysteine moieties of the proteins in contact with the nanoparticles. A proteomic analysis shows that the observed facet-dependent preferential binding of proteins is mostly related to the cysteine contents of the proteins, among commonly recognized protein properties controlling the formation of the protein corona. Theoretical calculations further demonstrate that the atomic arrangement of surface Cd atoms, as dictated by the exposed facets of the nanoparticles, controls the specific binding mode of the S atoms in the disulfide bonds of the proteins. Supplemental protein adsorption experiments confirm that disulfide bonds remain intact during protein adsorption, making the binding of protein molecules sensitive to the abundance and distribution of Cd-binding moieties and possibly molecular rigidity of the proteins. The significant conformational changes of adsorbed proteins evidenced from a circular dichroism spectroscopy analysis suggest that disrupting the structural stability of proteins may be an additional risk factor of Cd-bearing nanoparticles. These findings underline that the unique properties and behaviors of nanoparticles must be fully considered when evaluating the biological effects and health risks of metal pollutants.

C─H Activation Enables the Construction of New Bis-Polyaryl Phenylpyridine Ruthenium Complexes: Conjugation and Rigidity Synergistic Effect for Advanced Electrochemiluminescence.

The access to bench-stable organometallic compounds unfolds new chemical space for medicinal and material sciences. In particular, stable organoruthenium compounds with constitutional and stereoisomeric forms for subtle regulation of electrochemiluminescence are intriguing and challenging. Here, coordination of polycyclic aromatic hydrocarbons on (2-phenylpyridine)2(CO)2Ru complex allows access to bis-polyaryl phenylpyridine (BPP) Ruthenium complex through C─H activation strategy and coupling reactions for installation of the functionalities with steric and electronic purposes. The photoluminescence and electrochemiluminescence of BPP Ru complexes are affected by the actual polycyclic aromatic hydrocarbons inherent properties. The anthracene derivatized BPP Ru complex (BPP-Ant) shows the best ECL performance and reveals an enormous ECL quantum efficiency of 1.6-fold higher than the golden standard Ru(bpy)3 2+. The unprecedentedly high efficiency is due to the best compromise between the structural conjugation and molecular rigidity from BPP-Ant providing a providential energy gap that facilitated the feasibility of electron transfer and favored the radiative energy release by experimentally and DFT calculations. Moreover, PL and spooling ECL spectroscopies are used to track and link multiple emission peaks of BPP-Ant at 445, 645, and 845nm to different emissive species. These discoveries will add a new member to the efficient ECL ruthenium complex family and bring more potentials.

Constructing Stiffness Tunable DNA Hydrogels Based on DNA Modules with Adjustable Rigidity.

DNA hydrogel represents a potent material for crafting biological scaffolds, but the toolbox to systematically regulate the mechanical property is still limited. Herein, we have provided a strategy to tune the stiffness of DNA hydrogel through manipulating the rigidity of DNA modules. By introducing building blocks with higher molecular rigidity and proper connecting fashion, DNA hydrogel stiffness could be systematically elevated. These hydrogels showed excellent dynamic properties and biocompatibility, thus exhibiting great potential in three-dimensional (3D) cell culture. This study has offered a systematic method to explore the structure-property relationship, which may contribute to the development of more intelligent and personalized biomedical platforms.

Illuminating tetracycline: The role of metal coordination in fluorescence emission and its optical detection potential

Rapid on-site detection of antibiotics such as tetracycline (TC) is crucial for understanding their elusive environmental fate. Fluorescence-based strategies are promising owing to their sensitivity and ease of use. This study demonstrates that Al3+–TC coordination significantly enhances the intrinsic fluorescence of TC at excitation/emission wavelengths of 395/490 and 270/490 nm. The fluorescence emission intensity is proportional to the TC concentration between 0.005 and 7.5 μmol/L TC, which increases the detection sensitivity by 40 times compared with the commonly used absorption signals. Density functional theory calculations, when combined with the independent gradient model, indicate that the six-membered chelate ring in the octahedral Al3+–TC complex restricts molecular motion, along with two intramolecular hydrogen bonds formed between TC and water ligands. These factors lead to a narrowing of the energy gap between the highest occupied and lowest unoccupied molecular orbitals upon complexation with Al3+. Consequently, the enhanced molecular rigidity and facilitated electron transfer result in a significant increase in the fluorescence quantum yield. This captivating fluorescence response significantly enhances the proficiency of optical signals in detecting TC, thereby enriching future environmental monitoring systems with greater diversity and adaptability.

Solving the dilemma between reprocessability and mechanical properties faced by recyclable bio-based polyurethane foam through confining imine bonds in the hard domains

Introducing dynamic covalent bonds (DCBs) into polyurethane (PU) foams can solve the problem of their poor recyclability. However, a dilemma arises between reprocessability and mechanical robustness because of the low bond energies of DCBs. In this work, an aromatic diol (VAN-AM) containing imine bonds is synthesized to serve as the polyol together with castor oil. A series of bio-based polyurethane foams (BPUFs) with tunable bio-based carbon content, apparent density, cell properties and mechanical properties are prepared by adjusting the proportions of VAN-AM and castor oil. Benefiting from the molecular rigidity of VAN-AM, the dynamic imine bonds are enriched in the hard domains of PU. This allows for the kinetic control of the dynamicity of the PU networks. When the foams work at ambient temperature, which is much lower than the glass transition temperature of PU (113 ºC), the frozen segments of the hard domains inhibit the dynamic behavior of the imine bonds even if the latter may be somewhat activated (their triggering temperature ≈ 50 ºC). Consequently, the good mechanical properties of BPUFs can be maintained during service. At higher temperatures (> 113 ºC) or swollen state, the segmental mobility in the hard domains and dynamicity of imine bonds are greatly enhanced. Recycling of BPUFs is enabled as evidenced by hot-pressing the crushed foams into the compact sheets under mild conditions. The findings would facilitate the rational design of crosslinked polymeric foams with both high reprocessability and mechanical performance.

Modulating the Locally Excited States with a Regulating Substituent for Highly Efficient Red/Near‐Infrared Thermally Activated Delayed Fluorescence Emitters

AbstractDeveloping highly efficient red/near‐infrared (NIR) thermally activated delayed fluorescence (TADF) materials is important for organic light‐emitting diodes (OLEDs). Here, two TADF emitters, APTT and APTI, which have the same D/A backbone but different attaching groups at acenaphtho‐[1,2‐b]pyrazine‐8,9‐dicarbonitrile (APDC) core, are reported. The appended regulating groups can not only suppress the D/A rotation due to the space confinement effects but also modulate the locally excited triplet state (3LE). The improved molecular rigidity suppresses the non‐radiative process, accounting for the improved photoluminescence quantum yields (PLQYs), while the modulated 3LE promotes the reverse intersystem crossing (RISC) process due to the high utilization efficiency of triplets. Consequently, both APTT and APTI demonstrate high PLQY and fast RISC process, thereby enhancing TADF efficiency. The doped devices based on APTT and APTI achieve maximum external quantum efficiency (EQEmax) values of 20.5% and 25.4% with emission peaks at 664 and 670 nm, respectively. The non‐doped devices of APTT and APTI achieve the EQEmax of 2.8% and 2.9% with emission peaks at 788 and 794 nm, respectively. Encouragingly, the non‐doped devices of APTI have set new records for near‐infrared TADF OLEDs based on the APDC core. This study provides an efficient approach to modulating the optoelectronic properties of highly efficient NIR TADF OLEDs.

Plasticizer-based and polymer-free ion-selective optodes on cellulose paper

Paper-based ion-selective optodes (ISOs) allow for low-cost ion measurements using widely accessible optical detectors such as smartphones, representing an attractive analytical platform for medical testing and environmental monitoring. Previously reported paper-based ISOs rely on plasticized PVC membranes or PVC/plasticizer-free adsorption layers containing hydrophobic sensing chemicals. In this paper, we studied a new format of paper-based ISOs, in which a plasticizer phase containing sensing chemicals is deposited onto cellulose paper without using a hydrophobic polymer like PVC. Compared to ISOs without plasticizers and polymers, the plasticizer-based ISOs show much higher pH sensitivity when using chromoionophore I and tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the sensing chemicals. When the sensing layer further contains a solid ionophore with high molecular rigidity, the plasticizer-based ISOs for cations also exhibit enhanced sensitivity than the plasticizer-free ISOs. However, when the ionophore is a liquid at room temperature or has a long alkyl chain, the plasticizer-based and plasticizer-free ISOs have comparable responses because the ionophore behaves as a pseudo-plasticizer. Compared to ISOs with both plasticizers and polymers, the elimination of hydrophobic polymers like PVC makes inkjet printing more efficient and preserves the capillary action of the porous paper. By using the newly launched Samba cartridge with smaller nozzles, the plasticizer-based and polymer-free optodes for sodium, potassium, and calcium ions are prepared by inkjet printing for the first time. In an example application, the inkjet-printed plasticizer-based and polymer-free ISOs are used for colorimetric measurements of urine calcium.

Ionic Cross-Linked MOF-Polymer Mixed-Matrix Membranes for Suppressing Interfacial Defects and Plasticization Behavior.

To address the plasticization phenomenon and MOF-polymer interfacial defects, we report the synthesis of ionic cross-linked MOF MMMs from a dual brominated polymer and MOF components by using N,N'-dimethylpiperazine as the cross-linker. We synthesized brominated MIL-101(Cr) nanoparticles by using mixed linkers and prepared brominated polyimide (6FDA-DAM-Br) to form ionic cross-linked MMMs. The gas permeation properties of the polyimide, ionic cross-linked MOF-polymer MMMs, and non-cross-linked MOF-polymer MMMs with various MOF weight loadings were investigated systematically to effectively understand the effects of MOF weight loading and ionic cross-linking. The ionic cross-linked 40 wt % MOF-polymer MMM exhibited significantly enhanced gas permeability with an H2 permeability of 1640 Barrer and CO2 permeability of 1981 Barrer and slightly decreased H2/CH4, H2/N2, CO2/CH4 and CO2/N2 selectivities of 16.9, 15.4, 20.5, and 18.6, respectively. The H2 and CO2 permeabilities are approximately 2-3 fold higher than those of the pure polyimide (6FDA-DAM) membrane. Moreover, the ionic cross-linked 40 wt % MOF-polymer MMM exhibited significantly increased resistance to plasticization. This is because the brominated MOF incorporation boosted molecular transport and polymer chain rigidity, and ionic cross-linking further reduced the number of interfacial defects and polymer chain mobility.

Manipulating noncovalent conformational lock via side‐chain engineering for luminescence at aggregate level

AbstractThe unfavorable photochemical processes at the molecular level have become a barrier limiting the use of aromatic amides as high‐performance luminescent materials. Herein, we propose a reliable strategy for manipulating noncovalent conformational lock (NCL) via side‐chain engineering to burst out eye‐catching luminescence at the aggregate level. Contrary to the invisible emission in dilute solutions, dyad OO with a three‐centered H‐bond gave the wondrous crystallization‐induced emission with a quantum yield of 66.8% and clusterization‐triggered emission, which were much brighter than those of isomers. Theoretical calculations demonstrate that crystallization‐induced planarized intramolecular charge transfer (PICT), conformation rigidification, and through‐space conjugation (TSC) are responsible for aggregate‐state luminescence. Robust NCL composed of intramolecular N‐H···O interactions could boost molecular rigidity and planarity, thus greatly facilitating PICT and TSC. This study would inspire researchers to design efficient luminescent materials at the aggregate level via rational conformational control.

Novel indolocarbazole-based bipolar host materials for fabricating green phosphorescent organic light-emitting diodes with high efficiency and low roll-off

Herein we report two novel host materials, viz., 2-(dibenzo [b,d]furan-2-yl)indolo [3,2,1-jk]carbazole (ICz-DBF) and 3-(indolo [3,2,1-jk]carbazol-2-yl)furo [2,3-b:5,4-b']dipyridine (ICz-PFP), for fabricating highly stable and efficient organic light-emitting diodes (OLEDs). Green phosphorescent OLEDs (PhOLEDs) based on ICz-DBF and ICz-PFP exhibited less efficiency roll-off than those based on 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) host, and especially, the ICz-DBF-based device achieved a high external quantum efficiency (EQE) of 20.5 %. Bipolar hosts composed of indolocarbazole (ICz) exhibit strong molecular rigidity, high triplet energy, and fast electron transport properties; therefore, they act as acceptors, but dibenzofuran (DBF) and dipyridofuran (PFP) substitutions endow them with controlled electron-donating characteristics. The bipolar properties of the new host materials were demonstrated by single-carrier device analysis, confirming the effectiveness of our research strategy for developing hosts for high-quality OLEDs.

Exploring the aqueous solubility and intermolecular interactions of diclofenac Diethylammonium: A molecular modeling study in solid state and solvation processes

Diclofenac, a widely used non-steroidal anti-inflammatory drug with analgesic, anti-inflammatory, and antipyretic properties, presents a challenge in oral administration due to its low aqueous solubility and subsequent low bioavailability. This issue, primarily attributed to the drug's high hydrophobicity, can lead to adverse side effects. To address this, our study delves into the aqueous solvation process of diclofenac through molecular modeling, employing both Carr-Parrinello molecular dynamics and Density Functional Theory. This combined approach enables a comprehensive investigation of the molecular interactions that influence solubility, encompassing non-polar interactions (van der Waals dispersion forces), dipole interactions, and hydrogen bonding. Our results highlight the formation of intermolecular interactions with water molecules through OH⋯Owater and CO⋯Hwater hydrogen bonds. Additionally, we observe intramolecular hydrogen bonds within diclofenac (NH⋯OH and NH⋯Cl) and weaker interactions involving CH⋯Cl. Notably, the protonation of diclofenac contributes to molecular rigidity, hindering hydrogen bonding with adjacent water molecules further. These insights offer a deeper understanding of the solubility challenges associated with diclofenac, paving the way for improved drug formulations that enhance bioavailability. The application of Carr-Parrinello molecular dynamics and density functional theory in this study highlights their valuable role in addressing complex drug solubility and design issues.

Observation of anomalous low friction and wear behavior of polyimide in alkaline environment under high load

Polyimide (PI) was first discovered to exhibit excellent tribological properties in alkaline environments. PI is widely used because of its low thermal expansion coefficient, excellent mechanical properties, and resistance to high and low temperatures. The high manufacturing cost of PI makes its waste recycling a hot topic. The most common way of recycling is to hydrolyze PI in strong alkaline environments (C(OH−)>2 mol/L). Therefore, the intuition is that the friction performance of PI decline in highly corrosive environments. However, this paper found a counter-intuitive phenomenon. PI exhibits excellent tribological properties in alkaline environments. This paper studied the behavior of ball-on-disk contact between ceramic ball and PI disk tribopair in an alkaline environment. Results show a very low coefficient of friction (COF, 0.013) and wear rate (1.4 × 10−6 mm3/NM) in sodium hydroxide (NaOH) solution with pH = 13 under the average Hertzian contact pressure of 60 MPa. The COF and wear rate decreased by 80% and 63.4%, respectively, compared with those in solutions with pH = 7. The worn surface was characterized to explore the tribological mechanism. NaOH reacts with PI to form a polymer containing sodium ions during the friction process. The polymer adheres to the friction surface and improves the friction performance of PI. The chemical reaction breaks the C–N–C chemical bond of PI, thereby reducing the molecular rigidity and improving the adhesion of the PI surface. This paper provides a new modification method for improving the tribological properties of PI.