Alicyclic Diamines Research Articles

Semiaromatic Poly(ester imide) Copolymers with Alicyclic Diamines for Low-K Properties at a High Frequency of 10–40 GHz

Semiaromatic Poly(ester imide) Copolymers with Alicyclic Diamines for Low-K Properties at a High Frequency of 10–40 GHz

Synthesis of Highly Transparent Semi-aromatic Poly(amide–imide)s from Alicyclic Diamines and Dicarboxylic Acids Derived from 2,2'-Di(trifluoromethyl)benzidine with Trimellitic Anhydride

Synthesis of Highly Transparent Semi-aromatic Poly(amide–imide)s from Alicyclic Diamines and Dicarboxylic Acids Derived from 2,2'-Di(trifluoromethyl)benzidine with Trimellitic Anhydride

Photophysical analysis of dual fluorescence and phosphorescence emissions observed for semi-aliphatic polyimides at lower temperatures.

The photoluminescence (PL) properties of four types of blue fluorescent semi-aliphatic polyimides (PIs) derived from aromatic dianhydrides (ODPA, BPDA, HQDEA, and BPADA) and an alicyclic diamine (DCHM) were investigated at temperatures ranging from room temperature (RT, 298 K) to 30 K to analyse the origins of their non-radiative relaxation (NR) processes. These PIs exhibited significant increases in fluorescence (FL) intensity and lifetimes when lowering the temperature, stabilising below 100 K. The PIs containing ether (-O-) linkages showed a shoulder peak at around 500 nm below 150 K, which is attributable to phosphorescence (PH). These results show that the NR deactivation at RT includes three processes: intersystem crossing (ISC) from the excited singlet (S1) to the triplet (T1) state, temperature-dependent NR from the S1 state, which becomes suppressed below around 100 K, and temperature-independent NR. Based on the analyses of the temperature dependences, polymer structures, and quantum chemical analysis of molecular orbitals, we contemplate that the temperature-dependent NR is attributable to the excitation quenching by defect states mediated by excitation migration, and the temperature-independent NR may be caused by the deactivation of the excited state induced by molecular vibrations.

Synthesis and Characterization of Multicolor Luminescent and Thermally Stable Thioureas and Polythioamides.

Two new polythioamides were prepared through the polycondensation reaction between thiourea monomers and terephthaloyl dichloride, while the thiourea monomers were synthesized by the interaction of aromatic (4,4'-diaminophenylsulfone) or alicyclic (1,2-cyclohexanediamine) diamine with ammonium thiocyanate. The elemental composition of polythioamides was confirmed through CHN microanalysis. The structure and properties of thiourea monomers and polythioamides were determined through proton NMR, UV-Vis, FT-IR spectroscopy, fluorescence, TGA/DTA and SEM. The polythioamides indicated high thermal stabilities which were assessed from their Tmax (temperature indicating highest rate of weight loss) values (670 °C and 346 °C) observed in their DTG graphs. The thioureas and polythioamides were fluorescent and showed multicolor (violet, green, yellow, orange and red) emissions at different excitation wavelengths. All the synthesized compounds were also tested for their antifungal and antibacterial functions and showed antibacterial activity against Salmonella typhi, Bacillus subtilis and Staphylococcus aureus, and antifungal activity against Candida albicans.

Optically transparent (co)polyimides based on alicyclic diamines with improved dielectric properties

Optically transparent (co)polyimides based on alicyclic diamines with improved dielectric properties

A Transparent, Healable and Recyclable Alicyclic Poly(ether-b-amide) Multiblock Copolymer with Ultrahigh Toughness.

Self-healing polyamide multiblock copolymer with robust mechanical properties is highly desired. Here, an alicyclic diamine monomer, isophoronediamine (IPDA), with asymmetric structure and substantial steric hindrance was incorporated into the backbone of poly(ether-b-amide) multiblock copolymer. Based on the phase-lock effect, the mechanical properties and segmental mobility of copolymers can be modulated on a large scale via adjusting the molecular weight of hard segments. An extraordinary tensile strength of 32.0 MPa and an excellent elongation at break of 1881 % were simultaneously achieved, which leaded to a record-high toughness of 328.9 MJ m-3 for self-healable polyamide elastomers. The synergism between the dynamic H-bonding networks and the diffusion of polymer chains contributed to a balance between the mechanical performance and self-healing efficiency of copolymers. Due to the adjustable mechanical performance, rapid scratch self-healing ability and superior impact resistance, the resultant copolymers showed great potential in the fields of protective coatings and soft electronics.

Design and synthesis of novel arylurea derivatives of aryloxy(1-phenylpropyl) alicyclic diamines with antimicrobial activity against multidrug-resistant Gram-positive bacteria.

The alarming increase in the resistance of bacteria to the currently available antibiotics necessitates the development of new effective antimicrobial agents that are active against bacterial pathogens causing major public health problems. For this purpose, our in-house libraries were screened against a wide panel of clinically relevant Gram-positive and Gram-negative bacteria, based on which compound I was selected for further optimization. Synthetic efforts in a group of arylurea derivatives of aryloxy(1-phenylpropyl) alicyclic diamines, followed with an in vitro evaluation of the activity against multidrug-resistant strains identified compound 44 (1-(3-chlorophenyl)-3-(1-{3-phenyl-3-[3-(trifluoromethyl)phenoxy] propyl}piperidin-4-yl)urea). Compound 44 showed antibacterial activity against Gram-positive bacteria including fatal drug-resistant strains i.e., Staphylococcus aureus (methicillin-resistant, MRSA; vancomycin-intermediate, VISA) and Enterococcus faecium (vancomycin-resistant, VREfm) at low concentrations (0.78-3.125μg/mL) comparable to last resort antibiotics (i.e., vancomycin and linezolid). It is also potent against biofilm-forming S. aureus and Staphylococcus epidermidis (including linezolid-resistant, LRSE) strains, but with no activity against Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa). Compound 44 showed strong bactericidal properties against susceptible and drug-resistant Gram-positive bacteria. Depolarization of the bacterial cytoplasmic membrane induced by compound 44 suggests a dissipation of the bacterial membrane potential as its mechanism of antibacterial action. The high antimicrobial activity of compound 44, along with its selectivity over mammalian cells (lung MCR-5 and skin BJ fibroblast cell lines) and no hemolytic properties toward horse erythrocytes, proposes arylurea derivatives of aryloxy(1-phenylpropyl) alicyclic diamines for development of novel antibacterial agents.

Synthesis and evaluation of properties of the optically transparent (co)polyimides based on cyclic and alicyclic diamines and dianhydrides of aromatic tetracarboxylic acids

Synthesis and evaluation of properties of the optically transparent (co)polyimides based on cyclic and alicyclic diamines and dianhydrides of aromatic tetracarboxylic acids

Preparation and properties of light-colored and transparent semi-alicyclic polyimide films with enhanced flame retardancy from alicyclic dianhydrides and aromatic diamine containing phenolphthalein unit

Preparation and properties of light-colored and transparent semi-alicyclic polyimide films with enhanced flame retardancy from alicyclic dianhydrides and aromatic diamine containing phenolphthalein unit

White-Light Emission and Tunable Luminescence Colors of Polyimide Copolymers Based on FRET and Room-Temperature Phosphorescence.

Thermally stable copolyimide (CoPI) films exhibiting high optical transparency and room-temperature phosphorescence (RTP) were prepared by copolymerizing fluorescent dianhydride and brominated phosphorescent dianhydride with an alicyclic diamine. The CoPI films underwent a 5 wt % degradation at a temperature higher than 349 °C and exhibited dual fluorescent and phosphorescent emissions owing to their efficient Förster resonance energy transfer from the fluorescent to phosphorescent dianhydride moieties in the main chains, followed by an intersystem crossing from the singlet to triplet state of the latter moiety atoms. The CoPIs displayed bright RTP under a vacuum with various colors produced when adjusting the copolymerization ratio. CoPI with 5 mol % phosphorescent moiety (CoPI-05) emitted white light with high optical transparency owing to the suppression of the PI chain aggregation that causes a yellowish coloration. The copolymerization of fluorescent and phosphorescent PI moieties can control the photoluminescent properties of PI films and is applicable to color-tunable solid-state emitters, ratiometric oxygen sensors, and solar-spectrum converters.

Ru/g-C3N4 as an efficient catalyst for selective hydrogenation of aromatic diamines to alicyclic diamines.

A series of Ru/g-C3N4 materials with highly dispersed Ru were firstly prepared by an ultrasonic impregnation method using carbon nitride as a support. The catalysts were characterized by various techniques including BET and elemental analysis, ICP-AES, XPS, XRD, CO2-TPD and TEM. The results demonstrated that Ru/g-C3N4 materials with a mesoporous structure and highly dispersed Ru were successfully prepared. The chemo-selective hydrogenation of p-phenylenediamine (PPDA) to 1,4-cyclohexanediamine (CHDA) over Ru/g-C3N4 as a model reaction was investigated in detail. PPDA conversion of 100% with a CHDA selectivity of more than 86% could be achieved under mild conditions. It can be inferred that the carbon nitride support possessed abundant basic sites and the Ru/g-C3N4-T catalysts provided suitable basicity for the aromatic ring hydrogenation. Compared to the N-free Ru/C catalyst, the involvement of nitrogen species in Ru/g-C3N4 remarkably improved the catalytic performance. In addition, the recyclability of the catalyst demonstrated that the aggregation of Ru nanoparticles was responsible for the decrease of the catalytic activity. Furthermore, this strategy also could be expanded to the selective hydrogenation of other aromatic diamines to alicyclic diamines.

Soluble copolyimides containing 4,4′-isopropylidenedicyclohexanol (HBPA) isomer units: Synthesis, characterization, thermal, mechanical, and optical properties

In this work, 4,4′-isopropylidenedicyclohexanol (HBPA)-based dinitro isomers mixture (H″BPBN and H′BPBN) was synthesized and separated, and the structures of dinitro isomers were confirmed by differential scanning calorimetry and proton nuclear magnetic resonance spectroscopy. A series of copolyimides were prepared from diamino monomers with different percentages of novel diamine H″BPDA and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride via a conventional two-step procedure. All the copolyimides could afford flexible, tough, and transparent films with transmittance no less than 73% at 450 nm, which was attributed to the fact that nonplanar alicyclic diamine and the bulky and weakly polarizable trifluoromethyl hampered the formation of charge-transfer complex. Moreover, all the copolyimides were soluble not only in polar solvents such as N,N-dimethylformamide but also in low-boiling-point solvents such as dichloromethane, which was related to the fact that the existence of alicyclic diamine and bulky trifluoromethyl decreased the intermolecular force. In addition, the conformation effects of H″BPDA and H′BPDA on the aspects of thermal, mechanical, optical, and soluble performance of copolyimides were investigated and their structure–property relationships were discussed in detail.

Towards High-performance Materials Based on Carbohydrate-Derived Polyamide Blends.

A bio-derived monomer called 2,3:4,5-di-O-isopropylidene-galactarate acid/ester (GalXMe) has great potential in polymer production. The unique properties of this molecule, such as its rigidity and bulkiness, contribute to the good thermal properties and appealing transparency of the material. The main problem, however, is that like other biobased materials, the polymers derived thereof are very brittle. In this study, we report on the melt blending of GalXMe polyamides (PAs) with different commercial PA grades using extrusion as well as blend characterization. Biobased PA blends showed limited to no miscibility with other polyamides. However, their incorporation resulted in strong materials with high Young moduli. The increase in modulus of the prepared GalXMe blends with commercial PAs ranged from up to 75% for blends with aliphatic polyamide composed of 1,6-diaminohexane and 1,12-dodecanedioic acid PA(6,12) to up to 82% for blends with cycloaliphatic polyamide composed of 4,4′-methylenebis(cyclohexylamine) and 1,12-dodecanedioic acid PA(PACM,12). Investigation into the mechanism of blending revealed that for some polyamides a transamidation reaction improved the blend compatibility. The thermal stability of the biobased PAs depended on which diamine was used. Polymers with aliphatic/aromatic or alicyclic diamines showed no degradation, whereas with fully aromatic diamines such as p-phenylenediamine, some degradation processes were observed under extrusion conditions (260/270 °C).

Pressure-Induced Variations of Aggregation Structures in Colorless and Transparent Polyimide Films Analyzed by Optical Microscopy, UV-Vis Absorption, and Fluorescence Spectroscopy.

Pressure-induced variations in the main chain and aggregation structures of colorless and transparent semialiphatic polyimide (PI) films were investigated by optical microscopy, UV-vis absorption, and fluorescence spectroscopy up to 8 GPa. Upon application of pressures up to 2 GPa, a gradual volumetric compression was clearly observed by microscopy, and definite bathochromic shifts of locally excited (LE) absorption bands were detected, which was attributed to the compression of interchain free volume and enhanced intermolecular interactions. In addition, a significant reduction in fluorescence intensity was observed for PIs with quasilinear structures below 2 GPa due to enhanced energy transfer in the excited states caused by the densification of PI chain packing. In contrast, the volumetric compression of the PI films and bathochromic shifts of the LE absorption bands were gradually reduced at pressures above 2 GPa. The former is closely correlated with the bulkiness and flexibility of the alicyclic diamine structure. The latter reflects the intense compression stress generated around the dianhydride moiety, associated with the deformability and in-plane orientation of the main PI chains. High-pressure experiments on PI films are beneficial to investigate variations in aggregation structures and local electronic structures of PI chains induced by dense molecular packing and enhanced intermolecular interactions.

Some Peculiarities of Creation of Stable Polyimide - Azo Chromophore System

<p>Azo dyes: methyl orange, methyl red, congo red have been suggested as doping agents for formulation of stable soluble azo dye - polyimide (PI) system according to guest-host scheme. The dyes were added to<br />the reactive mixture of monomers: dianhydrides of alicyclic tetracarboxylic acids and aromatic diamines. Polyimide synthesis was carried out by one step polycyclocondensation in protolytic media. Addition of azo dyes influences on the molecular weights of final PIs. In great extent they depend on the nature and concentration of doping agent. Investigation of dependence of reduced viscosity of PI on monomers concentration, duration and temperature of synthesis, concentration of doping agent. It has been determined that addition of dyes to the reaction mixture up to definite value rises molecular weights of PIs from 45-50 000 up to 320-330 000. The most efficient catalyst is congo red. However some functional groups of azo dyes disturb equimolarity of the reaction by interaction with one of main monomers. The colour of thus doped PIs is stable under processing and high temperatures. Stability of the azo dye - polyimide system depends on interaction of NLO agent with polyimide chain. It is suggested that congo red molecules can coordinate with carbonyl groups of polymer. PI films display solvatochromic properties.</p>

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

Polymerization mechanism for radiation-induced grafting of styrene into alicyclic polyimide films for preparation of polymer electrolyte membranes

Alicyclic polyimides (APIs) derived from 1, 2, 4, 5-pyromellitic dianhydride (PMDA) bis(4-aminocyclohexyl)methane (DCHM) were successfully applied to radiation-induced graft polymerization for developing polymer electrolyte membranes for fuel cells. Pyromellitic-type CoPIs were prepared from PMDA and a mixture of aromatic and alicyclic diamines with certain molar ratios, and the radiation-induced grafting of styrene was then examined using pre-irradiation with a dose of 220kGy, followed by graft polymerization in a bulk styrene solution at 60°C. The grafting into fully aromatized polyimide barely proceeded (degree of grafting (DG) of less than 5%), whereas that of styrene into the API films proceeded with styrene DGs of up to 70%.Electron spin resonance measurements clearly showed that the irradiated API with the highest alicyclic component possessed the largest amount of radicals (up to 1.13 × 1018spins/g). Furthermore, in combination with ultraviolet–visible (UV–vis) spectroscopy, the radical species was identified as a long-lived intermediate with a spectrum containing λmax = 420 and 600nm, and 10% of the radicals were consumed as grafting initiators. Note that the alicyclic structure of the API films is advantageous for radiation-induced graft polymerization because of the generation of high-concentration initiation radicals.The moderate reaction conditions allowed for selective sulfonation on the polystyrene grafts, and not on the API substrates, to give API-based polymer electrolyte membranes (PEMs) with ion exchange capacities (IECs) of 1.7–2.8mmol/g. The PEMs exhibited appropriate proton conductivity (0.06 ≤ σ ≤ 0.34S/cm) and low water uptake (≤100%), together with excellent mechanical properties (tensile strength, 90MPa), compared with conventional PEMs such as Nafion®.

Short-block polyurea-polydimethylsiloxane block copolymers based on secondary diamines

New short-block polyurea-polydimethylsiloxane block copolymers based on aliphatic and alicyclic secondary diamines and diisocyanates as well as on oligodimethylsiloxanes with glycidyl end groups were synthesized through a two-stage method. With the use of DSC and small-angle X-ray scattering methods, it was shown that, in the resulting block copolymers, in spite of the short block lengths, microphase separation occurs. The sizes of the formed domains, which correspond to the interplanar distances, decrease monotonically with a decrease in the sizes of the rigid and elastic blocks and become as low as 6.0–11.1 nm. The stress-strain characteristics of block copolymers are dependent above all on the ratio of blocks.

Proton-Bridge Motions in Amine Conjugate Acid Ions Having Intramolecular Hydrogen Bonds to Hydroxyl and Amine Groups

Vibrational spectra of two gaseous cations having NH···O intramolecular ionic hydrogen bonds and of nine protonated di- and polyamines having NH···N internal proton bridges, recorded using IR Multiple Photon Dissociation (IRMPD) of mass-selected ions, are reported. The band positions of hydroxyl stretching frequencies do not shift when a protonated amine becomes hydrogen bonded to oxygen. In three protonated diamines, lower frequency bands (550-650 cm(-1)) disappear upon isotopic substitution, as well as several bands in the 1100-1350 cm(-1) region. By treating the internal proton bridge as a linear triatomic, theory assigns the lowest frequency bands to N-H···N asymmetric stretches. A 2-dimensional model, based on quantization on a surface fit to points calculated using a double hybrid functional B2-P3LYP/cc-pVTZ//B3LYP/6-31G**, predicts their positions accurately. In at least one case, the conjugate acid of 1,5-cis-bis(dimethylamino)cyclooctane, a N-H···N bend shows up in the domain predicted by DFT normal mode calculations, but in most other cases the observed bands have frequencies 20-25% lower than expected for bending vibrations. Protonated Me(2)NCH(2)CMe(2)CH(2)CH(2)CH(2)NMe(2) shows three well-resolved bands at 620, 1200, and 1320 cm(-1), of which the lowest can be assigned to the asymmetric stretch. Other ions observed include doubly protonated 1,2,4,5-(Me(2)NCH(2))(4)-benzene and 1,2,4-(Me(2)NCH(2))(3)-benzene-5-CH(2)OH. Apart from the aforementioned rigid ion derived from the alicyclic diamine, the other ions enjoy greater conformational mobility, and coupling to low-frequency C-C bond torsions may account for the shift of vibrations with N-H···N character to lower frequencies. Low-barrier hydrogen bonding (LBHB) accounts for the fact that N-H···N asymmetric stretching vibrations of near linear proton bridges occur at frequencies below 650 cm(-1).

Nanoporous thin films of fully alicyclic polyimides

Nanopore generation could be accomplished in thin films of fully alicyclic polyimides derived from an alicyclic dianhydride and diamines. A silylation method for the alicyclic diamines was used to synthesize high molecular weight alicyclic polyimides. Triblock copolyimides were prepared using N-silylated alicyclic diamines, alicyclic dianhydride, and a thermally labile polymer. Nanoporous films of fully alicyclic polyimides were prepared through heating of the copolyimide films to induce thermal degradation of the labile block. Open image in new window