Polyimide Networks Research Articles

Anti-adhesive and bactericidal polymeric coating based on Schiff-base reaction

Herein, we report an effective bacterial anti-adhesive and bactericidal coating based on a Schiff-base reaction. The hydrophilic polyoxyethylene-bis-amine (PEG-bis-amine) is introduced in the system to endow the coating with valid bacterial anti-adhesive performance, while the tobramycin (Tob) with multi-amines serves as both a bactericidal agent and one of the cross-linkers for the construction of polyimide networks. The coating is obtained via a facile solvent-annealing method. This type of dual-functional antibacterial coating may provide as an excellent antibacterial platform for broad applications in bactericidal surfaces.

Molecular design of interpenetrating fluorinated polyimide network with enhanced high performance for heat-resistant matrix

Novel reactive phenylethynyl-endcapped diluents were synthesized and physically mixed with fluorinated cooligoimides (molecular weights of 5000 g/mol) derived from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 2,2′-bis(trifluoromethyl)-4,4′-diamino biphenyl (TFDB) and para-phenylenediamine (p-PDA) at 25/75 M ratio, and 4-phenylethyethynylphthalic anhydride (PEPA) to formulate blends served as matrix resins for developing high-performance composites with excellent processabilities. The uncured blend shows very low minimum melt viscosity (<1 Pa s) and extended process window achieved using molten solvation of reactive diluent to prevent intermolecular interactions and recrystallization at higher temperature. This blend was converted to interpenetrating polyimide network through thermal-curing of phenylethynyl end-groups in each constituent. The morphology, relaxation transition and mechanical property were investigated as functions of mass fraction and chemical configuration of reactive diluent. The covalent incorporation of crosslink structures restricts segmental motion while backbone linkage induces strength and toughness retention. This cooperative effect endows homogeneous networks with high glass transition temperatures (435 °C) and flexural strength (130 MPa) simultaneously.

Fabrication of microporous polyimide networks with tunable pore size and high CO2 selectivity

Developing porous organic polymer materials with plenty micropores is of great importance for highly selective CO2 capture under ambient conditions. Here, to tune the pore size, two novel microporous hyperbranched polyimide networks, in which the distance between the polymer skeleton and crosslinking points is different, are successfully prepared by a two-step pathway combining polymerization and crosslinking reaction. It is intriguingly found that both porosity and CO2 sorption performance of microporous hyperbranched polyimides can be finely tuned by reducing the distance between the polymer skeleton and crosslinking points from PEPHQDA-HBPI-CL to PEQDA-HBPI-CL. The micropore size decrease from 1.18 nm to 0.86 nm, and CO2 adsorption capacity increase from 6.38 to 6.51 wt% (298 K and 1 bar). More excitingly, the PEQDA-HBPI-CL demonstrates the high CO2/N2 and CO2/CH4 selectivity up to 109 and 15 (273 K, 1 bar) according to the Henry's law, which are superior to those of many other microporous organic polymers and among the best results for porous inorganic/ organic materials. This work reveals that the shorter-distance between the polymer skeleton and crosslinking points is in favor of fabricating microporous hyperbranched polyimide networks with abundant smaller micropore and high CO2 selectivity, which are crucial importance for the CO2 capture and storage.

Porphyrin-based porous polyimides: Synthesis, porous structure, carbon dioxide adsorption

A novel dianhydride 3,3’-bis(3,4-dicarboxyphenoxy)-4,4’-diphenylethynyl biphenyl dianhydride (BPEBPDA) and a new tetramine monomer 5,10,15,20- tetra[4-[(3-aminophenyl)ethynyl]phenyl]porphyrin (TAPEPP) were successfully synthesized. Porphyrin-based polyimides (PPBPIs) were synthesized from BPEBPDA and porphyrin-based building blocks (TAPP and TAPEPP) via polymerization reactions. The porphyrin-based porous polyimide networks (PPBPI-CRs) were obtained from PPBPIs through thermal crosslinking reactions. The PPBPI-CRs exhibited BET surface areas (682 m2 g−1 and 693 m2 g−1) and CO2 uptakes (2.0 mmol g−1 and 1.67 mmol g−1 at 273 K and 1 bar) as well as the separation factors of CO2/N2 (37.63, 28.97) and CO2/CH4 (7.51, 5.61). Meanwhile, PPBPI-CRs showed an enhanced CO2 isosteric enthalpies of adsorption (25.1 kJ mol−1 and 30.1 kJ mol−1) than other porous polymers.

Adsorption of acid orange 10 on cross-linked porous polyimide

In this work, a cross-linked porous polyimide (PI) network, fabricated from an “elongated” dianhydride and melamine, was synthesized by polycondensation and thermal dehydration. The as-prepared PI revealed an excellent adsorption performance and removal for acid orange 10 (AO-10) from aqueous solution. The adsorption quantity can reach 599 mg/g when the initial concentration is 500 mg/L with the temperature 298 K and pH value of 3. The maximum desorption ratio can be 38.9%. It is expected that the adsorption quantity and desorption ratio can be optimally improved by changing the length of PI monomer, indicating the cross-linked porous PI network is not only served effectively in sewage treatment but also recycled. Pseudo-2nd-order kinetic model and Langmuir isotherm are better fitted with the kinetic data and the adsorption equilibrium data respectively.

Construction and carbon dioxide capture of microporous polymer networks with high surface area based on cross-linkable linear polyimides

Microporous polyimide networks with high surface area and excellent CO2 adsorption performance have been constructed based on cross-linkable linear polyimides through crosslinking reaction.

Highly Selective Separation of CO2, CH4, and C2-C4 Hydrocarbons in Ultramicroporous Semicycloaliphatic Polyimides.

Ultramicroporous semicycloaliphatic polyimides with major pore sizes less than 0.5 nm are synthesized through imidization reaction between different aromatic tetraamines and cycloaliphatic dianhydrides. The synergistic role of abundant CO2-philic imide rings and the molecular sieving effect of ultrasmall pores in the polyimide network bring about high adsorption selectivity of CO2/CH4 (37.2) and CO2/N2 (136.7). In addition, it is interesting to observe that, under ambient condition (298 K/1 bar), n-butane exhibits the highest uptake (3.15 mmol/g) among the C1-C4 alkanes, and the adsorbed amount significantly drops with the reduction of the number of carbon atoms. As a result, the mixed light alkanes can be effectively separated according to the carbon numbers. The separation factors of n-butane/propane and propane/ethane reach 3.1 and 6.5, whereas those of n-butane, propane, and ethane over methane are as high as 414.5, 217.4, and 19.6, respectively. Moreover, the polyimides display large adsorption capacities for 1,3-butadiene (4.64 mmol/g) and propene (2.68 mmol/g) with good selectivity over 1-butene and propane of 3.2 and 3.0, respectively. Together with the excellent thermal and physicochemical stabilities, the ultramicroporous polyimides obtained in this work show promising applications in adsorption/separation for CO2, CH4, and C2-C4 hydrocarbons.

Skin-inspired highly stretchable and conformable matrix networks for multifunctional sensing

Mechanosensation electronics (or Electronic skin, e-skin) consists of mechanically flexible and stretchable sensor networks that can detect and quantify various stimuli to mimic the human somatosensory system, with the sensations of touch, heat/cold, and pain in skin through various sensory receptors and neural pathways. Here we present a skin-inspired highly stretchable and conformable matrix network (SCMN) that successfully expands the e-skin sensing functionality including but not limited to temperature, in-plane strain, humidity, light, magnetic field, pressure, and proximity. The actualized specific expandable sensor units integrated on a structured polyimide network, potentially in three-dimensional (3D) integration scheme, can also fulfill simultaneous multi-stimulus sensing and achieve an adjustable sensing range and large-area expandability. We further construct a personalized intelligent prosthesis and demonstrate its use in real-time spatial pressure mapping and temperature estimation. Looking forward, this SCMN has broader applications in humanoid robotics, new prosthetics, human–machine interfaces, and health-monitoring technologies.

Facile preparation of cross-linked polyimide aerogels with carboxylic functionalization for CO2 capture

In this study, highly cross-linked and completely imidized polyimide aerogels containing carboxyl groups were successfully synthesized using a mild sol-gel method at room temperature from 3,5-diaminobenzoic (DABA) and biphenyl-3,3′,4,4′-tetracarboxylic (BPDA) and cross-linked with 1,3,5-triaminophenoxybenzene. The densities of the obtained polyimide aerogels are between 0.116 and 0.386g/cm3, the specific surface areas range from 173 to 461m2/g, and the porosities are as high as 97%. The CO2 adsorption-desorption isotherms are reversible, and the CO2 uptakes at 25°C and 1bar are as high as 21.10cm3/g, which are comparable to those of previously reported microporous organic polymers. The high CO2 adsorptions are attributed to the abundance of electron-rich heteroatoms in the polyimide networks and to the presence of carboxyl groups, a type of CO2-philic group. The facile preparation and high CO2 adsorptive capacity indicate that polyimide aerogels may be ideal candidates for capturing CO2.

From a flexible hyperbranched polyimide to a microporous polyimide network: Microporous architecture and carbon dioxide adsorption

A dianhydride monomer 2, 5-bis(3, 4-dicarboxyphenoxy)-4′-phenylethynyl biphenyl (PEPHQDA) containing a chain extendable phenylethynyl pendant group has been successfully synthesized via successive nucleophilic substitution, Sonogashira cross-coupling, hydrolysis and dehydration reactions. A flexible microporous polyimide network has been prepared based on the use of triamine (TAPOB), affording hyperbranched polyimide, followed by the curing of phenylethynyl groups to give network structure. Specifically microporous features such as a well-defined surface morphology, microporous structure and nanometer-sized pore channels have been introduced to the flexible polyimide networks through this two-step pathway. This network exhibit a BET surface area (322 m2 g−1) as well as a comparable CO2 uptake (1.25 mmol g−1 at 273 K and 1 bar) and enthalpy of adsorption (30.3 kJ mol−1) to that of other microporous polyimides derived from rigid tridimensional monomers.

The Triazine‐based Porous Organic Polymer: Novel Synthetic Strategy for High Specific Surface Area

The tetraphenylmethane modified with 2,4-diaminotriazine can effectively provide a hyperbranching point in the polyimide network, resulting in high specific surface area with 1150 m2/g, and its pore structure in the solid state can be simply controlled by the surface activation method.

Microporous polyimide networks constructed through a two-step polymerization approach, and their carbon dioxide adsorption performance

A series of microporous polyimide networks were preparedviaa novel two-step pathway combining polymerization and crosslinking reactions.

Microporous Organic Polyimides for CO2 and H2O Capture and Separation from CH4 and N2 Mixtures: Interplay between Porosity and Chemical Function

Porous polyimides have been considered to be a promising material class for gas capture and sequestration, leading to the synthesis of a substantial number of individual networks with noteworthy sorption properties. In spite of these efforts, the vision of a chemical control of adsorption and desorption of small molecules, in particular, for the competing uptake of technical relevant gas mixtures, is still hardly investigated. Here, we present a systematic study of five new polyimide networks based on a set of linkers with chemical functionalities covering the full range from hydrophobic to hydrophilic interactions. The corresponding microporous organic polyimides (MOPI-I to -V) were synthesized successfully based on a condensation reaction between amino and anhydride linker molecules in m-cresol at high temperatures, resulting in cross-linking degrees beyond 95% in all cases. Argon and carbon dioxide isotherms reveal surface areas up to 940 m2/g with ultramicroporosity, about 50% microporosity and high t...

Mechanical and thermal characterization of a novel nanocomposite thermal interface material for electronic packaging

This paper presents a novel nanocomposite thermal interface material (Nano-TIM) consisting of a silver coated polyimide network and the indium matrix. One of the potential applications of this Nano-TIM is for heat dissipation in integrated circuits and electronic packaging. The shear strength of the Nano-TIM was investigated with DAGE-4000PSY shear tester. The shear strength of Nano-TIM is 4.5MPa, which is 15% higher than that of the pure indium thermal interface material. The microstructure of cross-section and fracture surface was studied using Scanning Electron Microscopy (SEM). SEM pictures show a uniform polymer fiber distribution and solid interface between silver coated fibers and indium matrix. The thermal fatigue resistance of the Nano-TIM was evaluated by monitoring the variation of thermal interface resistance during the thermal cycling test (−40 to 125°C). The thermal interface resistance was measured with a commercial xenon flash instrument after 100, 200, 300, 400, 500, and 1000 temperature cycles. The results of thermal cycling test show that Nano-TIM presented consistent reliability performance with pure indium. Furthermore, the cooling effect of Nano-TIM was demonstrated through measuring the power chip temperature in the die attached structure by using an Infrared Camera. In the test, the Nano-TIM shows a comparable cooling effect to pure indium TIM for die attach applications in electronics packaging.

Reversely swellable porphyrin-linked microporous polyimide networks with super-adsorption for volatile organic compounds

A series of microporous polyimide networks with porphyrin units (Pr-MPIs) were facilely synthesized through a one-step solution polymerization process. Of particular interest is that Pr-MPI-1 containing distorted spirobisindane unit revealed the highest BET surface area (953 m2/g), total pore volume (0.75 cm3/g), and extreme hysteresis between the N2 adsorption and desorption isotherm. Further study revealed the prepared Pr-MPI-1 exhibited a synergistic structural effect on exceptional uptake of volatile organic compounds (VOCs) due to the high porosity and highly distorted spirobisindane structure enabled large interface and the swellability. This new approach would open up a facile approach toward the preparation of highly swellable high performance polymeric microporous materials, which are deeply wanted for environment-related applications such as VOCs adsorption and oil/water separation.

Fluorescent Microporous Polyimides Based on Perylene and Triazine for Highly CO2-Selective Carbon Materials

Carbon dioxide (CO2) capture from point sources like coal-fired power plants is a potential solution for stabilizing atmospheric CO2 content to avoid global warming. Sorbents with high and reversible CO2 uptake, high CO2 selectivity, good chemical and thermal stability, and low cost are desired for the separation of CO2 from N2 in flue or natural gas. We report here, for the first time, on the synthesis of new microporous polyimide (PI) networks from the condensation of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and 1,3,5-triazine-2,4,6-triamine (melamine) using a Lewis acid catalyst zinc acetate/imidazole complex. These PI network materials, prepared in the absence and presence of dimethyl sulfoxide (DMSO) as weak solvent template, exhibit strong fluorescence. Nitrogen-containing carbons can be accessed from our PI networks via a simple thermal pyrolysis route. The successful construction of new microporous PI networks and derived N-containing carbons is shown here to provide promising CO2 sor...

Tetraphenyladamantane-Based Microporous Polyimide and Its Nitro-Functionalization for Highly Efficient CO2 Capture

A new microporous polyimide network (PI-ADNT) is synthesized from 1,3,5,7-tetrakis(4-aminophenyl)adamantane and naphthalene-1,4,5,8-tetracarboxylic dianhydride. Subsequently, PI-ADNT is nitrated in fuming nitric acid with different nitration time to produce three nitro-decorated porous polyimides (PI-NO2s). Their chemical structures and nitration degrees are characterized by FTIR, solid-state 13C CP/MAS NMR spectra and element analysis. The interesting evolution of porous morphology and porosity of PI-NO2s with nitration time is investigated in detail. The results show that PI-ADNT has the BET surface area of 774 m2 g–1 with microporous size centering at 0.75 nm. After nitration-modifications, PI-NO2s display decreased surface area but remarkably increased CO2 uptake up to 4.03 mmol g–1, which is superior to most of porous polymers reported in the literature. Moreover, the CO2 adsorption selectivites over CH4 and N2 in PI-NO2s are also significantly improved in comparison with PI-ADNT. The CO2 adsorption/separation properties of PI-ADNT and its nitrated products are studied and explained in terms of the variations of porous structure and chemical composition as well as the interaction parameters between CO2 molecule and polymer skeleton such as Henry’s constant, first virial coefficient, and enthalpy of adsorption.

Synthesis and characterization of fully aliphatic polyimides from an aliphatic dianhydride with piperazine spacer for enhanced solubility, transparency, and low dielectric constant

A new series of fully aliphatic polyimide (API) based on a novel aliphatic dianhydride monomer-2,20-(1,4-piperazinediyl)-disuccinic anhydride (PDA), in which two units of succinic anhydride have been connected by an aliphatic heterocyclic piperazine spacer that possesses aminomethylene (-NCH2) moiety in the aliphatic/alicylic backbone capable of inducing charge transfer (CT) interactions in the polyimide network, was successfully synthesized. The APIs were soluble in common polar organic solvents. The polyimide films of PDA with alicyclic diamines were almost colorless. T10 (temperature of 10% weight loss) of APIs were ranged from 299–418 C and Tg of API3-API6 were in the temperature range of 170 to 237 C. The light-colored polyimide films of API3-API6 possessed good mechanical properties with tensile strength of 54–72 Mpa, tensile modulus of 1.6–2.3 Gpa and elongation at break of 4–9%. The polyimide films of API3-API6 were highly flexible and freestanding which is quite rare in fully APIs. The dielectric constant of one of the synthesized API (API4) was as low as 2.14. VC 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 00, 000–000

Macromol. Chem. Phys. 10/2014

Front Cover: The framework structure of rigid poly(amide acid) and polyimide networks can be tuned by the selection of a robust and symmetric crosslinker structure. The S4-symmetric four-armed crosslinker can provide homogeneous network structures compared with the C3-symmetric three-armed crosslinker. Further details can be found in the article by N. Yoshihara, N. Hosono,* R. Ohshima, K. Totani, and T. Watanabe* on page 988.

Rigid Polyimide Networks End-Linked with Tri- and Tetra-armed Crosslinkers

Rigid polymer networks with aromatic polyimide (PI) backbones end-linked with symmetric crosslinkers are designed. 1,3,5-Tris(4-aminophenyl)benzene (TAPB) and tetra(4-aminophenyl)methane (TAPM) are used as the crosslinkers. Whereas TAPB has three reactive amines at planar threefold symmetric (C3) positions, TAPM has four amines at tetragonal (S4) positions. Poly(amide acid) (PAA) precursors are end-linked with TAPB or TAPM to make PAA networks. The crosslinking reaction efficiencies and mechanical properties of the PAA gels are investigated by the sol fraction method and compressive stress–strain tests, respectively. The PAA gels are successively transformed to PI gels through chemical imidization treatments. From the swelling behavior, it is found that the PI gels have high void contents up to 70%.