Aliphatic Segments Research Articles

Equilibrium Structure, Hydrogen Bonding, and Proton Conductivity in Half-Neutralized Diamine Ionic Liquids.

Recent experiments on proton conducting ionic liquids point to half-neutralized diamine-triflate salts as promising candidates for applications in power generation and energy conversion electrochemical devices. Structural and dynamical properties of the simplest among these compounds are investigated by a combination of density functional theory (DFT) and molecular dynamics (MD) simulations based on an empirical force field. Three different cations have been considered, consisting of a pair of amine-ammonium terminations joined by a short aliphatic segment -(CH2) n- with n = 2, 3, and 4. First, the ground state structure, vibrational eigenstates, and hydrogen-bonding properties of single ions, neutral ion pairs, small neutral aggregates of up to eight ions, and molecularly thin hydrogen bonded wires have been investigated by DFT computations. Second, structural and dynamical properties of homogeneous liquid and amorphous phases are investigated by MD simulations over the temperature range of 200 ≤ T ≤ 440 K. Structure factors, radial distribution functions, diffusion coefficient, and electrical conductivity are computed and discussed, highlighting the inherent structural heterogeneity of these compounds. The core investigation, however, is the characterization of connected paths consisting of cation chains that could support proton transport via a Grotthuss-type mechanism. Since simulations are carried out using a force field of fixed bonding topology, this analysis is based on the equilibrium structure only, using geometrical criteria to identify potential paths for proton conduction. Paths of connected cations can reach a length of 80 cations and 30 Å, provided that bridging oxygen atoms from triflate anions are taken into account. The effects of water contamination at 1% weight concentration on the structure, dynamics, and paths for proton transport are discussed.

Crystal structure and Hirshfeld surface analysis of N,N'-bis-(2-nitro-phen-yl)glutaramide.

The asymmetric unit of the title compound, C17H16N4O6, contains two independent mol-ecules (A and B). The two benzene rings are twisted by an angle of 79.14 (7)° in mol-ecule A, whereas, in mol-ecule B, they are inclined by 19.02 (14)°. The conformations of the mol-ecules are stabilized by intra-molecular N-H⋯O hydrogen bonds between the amide nitro-gen atom and the O atom of the ortho-nitro substituent on the phenyl ring, enclosing an S(6) ring motif. In the amide and aliphatic segments, all the N-H, C=O and C-H bonds are anti to each other. In the crystal, the A and B mol-ecules are linked by inter-molecular amide-to-amide N-H⋯O hydrogen bonds, resulting in chains running along the b-axis direction. The inter-molecular inter-actions were analysed using Hirshfeld surface analysis. The two-dimensional fingerprint plots of the inter-molecular contacts indicate that the major contributions are from H⋯H and O⋯H inter-actions.

Redefining polyamide property profiles via renewable long-chain aliphatic segments: Towards impact resistance and low water absorption

A series of renewable, long-chain, fatty acid-derived polyamides (PA) ranging from PA 6,14 to PA 6,18 were synthesized via polycondensation, yielding very high molecular weights and a remarkable property profile distinct from short-chain commercial grades. Most notably, synthesized polyamides exhibited good impact resistance, excellent stiffness-to-toughness balance and very low water absorption yet high oxygen and water vapour permeability; with this property profile being exemplified by PA 6,18. The increased repeating unit length and reduced number of amide linkages able to participate in interchain hydrogen bonding imparted a strong influence on material properties. The data highlights the benefits and technical advantages of utilising long-chain polyamides, while also significantly expanding the repertoire, knowledge and property profile of the long-chain aliphatic polyamide family, and providing a basis for further development of polyamides from renewable sources.

Renewable polyamides via thiol-ene ‘click’ chemistry and long-chain aliphatic segments

Thiol-ene ‘click’ chemistry was utilised to prepare dicarboxylic acid monomers containing two sulphur units within the backbone, which subsequently underwent polycondensation to yield a series of renewable, long-chain, fatty-acid derived linear polyamides. The linear sulphur-containing polyamides displayed number-average molecular weights of 8000–55,000 g·mol−1 and broad polydispersities biased towards higher weight fractions. Glass transition values were slightly above room temperature (31–35 °C), while melting temperatures ranged from 121 to 170 °C. This novel class of polymers exhibited an impressive property profile, most notably exceptional impact resistance, tear strength, high elasticity, very low water absorption yet high oxygen- and water vapour permeability. The presence of sulphur and the increased aliphatic segment length influenced a wide spectrum of polyamide properties due to the reduced amide linkage (and inter-chain hydrogen bonding) density and less-effective chain packing ability due to the increased atomic radii of the sulphur atoms. The data highlights the technical advantages of these polymers, while also expanding the repertoire and structure-property relationships of both long-chain- and sulphur-containing polyamides, and encouraging further development of polyamide derivatives from renewable sources.

Synthesis and Study of Poly(ether-amide)s Containing Aromatic and Aliphatic Ether-Amine Segment and Isophthalic Acid

The paper describes some physical properties of poly(ether-amide)s (PEAs) prepared by solution polycondensation reaction of ether-amines such as 2,7-bis(4-aminophenoxy) naphthalene, 2,2-bis[4-(4-aminophenoxy)phenyl] propane, 1,4-bis(4-aminophenoxy methyl) cyclohexane and isophthalic acid. Resulting PEAs are high yield and have inherent viscosity ranging between 0.68–0.75 dL/g. The etheramines containing wholly, semi aromatic and aliphatic-aromatic segments were prepared by using two steps reaction. FTIR, 1H NMR, and elemental analyses were used for characterization of synthetic ether-amines and poly(ether-amide)s. PEAs films were prepared by solution casting technique then their thermal stability and mechanical properties were measured. TGA in nitrogen atmosphere shows that the PEAs are thermally stability, so 10% weight will be lost in the range of 335–358°C. Tensile strength and elongation at break of the PEA films ranged from 71.1–65.0 MPa and 6.48–8.41%, respectively.

Thermoplastic Polyurethane Elastomers with Aliphatic Hard Segments Based on Plant‐Oil‐Derived Long‐Chain Diisocyanates

AbstractNovel plant‐oil‐derived long‐chain (C19 and C23) α,ω‐diisocyanates, optionally in combination with the corresponding long‐chain diols, provide entirely aliphatic hard segments in segmented thermoplastic polyurethane elastomers (TPUs), with carbohydrate‐based poly(trimethylene glycol) soft segments. Compared to materials based on a mid‐chain monomer analog, phase separation is higher due to an increased flexibility of the aliphatic segments. Although melting points are slightly lower than for HDPE, the long‐chain TPU's solid‐state structure is still dominated by hydrogen‐bonding.

Cluster Formation of Polyphilic Molecules Solvated in a DPPC Bilayer.

We analyse the initial stages of cluster formation of polyphilic additive molecules which are solvated in a dipalmitoylphosphatidylcholine (DPPC) lipid bilayer. Our polyphilic molecules comprise an aromatic (trans-bilayer) core domain with (out-of-bilayer) glycerol terminations, complemented with a fluorophilic and an alkyl side chain, both of which are confined within the aliphatic segment of the bilayer. Large-scale molecular dynamics simulations (1 s total duration) of a set of six of such polyphilic additives reveal the initial steps towards supramolecular aggregation induced by the specific philicity properties of the molecules. For our intermediate system size of six polyphiles, the transient but recurrent formation of a trimer is observed on a characteristic timescale of about 100 ns. The alkane/perfluoroalkane side chains show a very distinct conformational distribution inside the bilayer thanks to their different philicity, despite their identical anchoring in the trans-bilayer segment of the polyphile. The diffusive mobility of the polyphilic additives is about the same as that of the surrounding lipids, although it crosses both bilayer leaflets and tends to self-associate.

Polyimides from an asymmetric hydroxyl‐containing aliphatic‐aromatic diamine synthesized via henry reaction

ABSTRACTAn aliphatic amino and an aliphatic hydroxyl group have been incorporated via Henry reaction highly efficiently toward the synthesis of a novel asymmetric aliphatic–aromatic diamine 2‐amino‐1‐[4‐(5‐aminopyridyloxy)phenyl]‐1‐ethanol (AAPyPhE) in three steps. AAPyPhE shows good copolymerization reactivity with 4,4′‐oxydianiline (ODA) toward different aromatic dianhydrides, especially 4,4′‐oxydiphthalic anhydride (ODPA). TGA measurement and mechanical test results show that all polymers maintain the inherent thermal performance and tensile properties, while the glass transition temperatures (Tg's) by DMA show moderate decrease ranging from 185.5 to 253.3 °C due to the presence of aliphatic segments. The introduction of AAPyPhE is found to improve the solubility of the polymers, and the polymer films' optical transparency with decreased cutoff wavelength (λ0) ranging from 328 to 370 nm. Comparative studies reveal that the pendent aliphatic hydroxyls in the polymer chains would lead to interchain cross‐linking via condensation and secondary weak cross‐linking by hydrogen bond depending on different loading of AAPyPhE, which result in a fluctuation of hydrophilic–hydrophobic properties, DMA tan δ and dielectric constant of the copolymer films. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3413–3423

Synthesis, Characterization, and Application Studies of Polyurethane Acrylate Thermoset Coatings: Effect of Hard Segment

ABSTRACTThe waterborne polyurethane acrylate coatings are smart option to reduce the environmental hazards. To evaluate the structure–property relationship, polyurethane acrylate coating dispersions were synthesized with aromatic and aliphatic hard segments. Furthermore, to evaluate the performance, dispersions were used to finish the cotton fabric. The dispersions were prepared by prepolymer method followed by emulsion polymerization in aqueous medium. The characterization of dispersions was performed by Fourier transform infrared, dynamic light scattering, atomic force microscopy, differential scanning calorimetry, and thermogravimetric analysis. In general, aliphatic hard segment has shown more appreciable results. But, thermal stability of aromatic polyurethane acrylate was more pronounced as inherent rigidity of aromatic diisocyanate dominates.

Thermal-oxidation of epoxy/amine followed by glass transition temperature changes

Thermal oxidation of three epoxy resins differing by the nature of prepolymer (bisphenol A diglycidyl ether and 1,4-butanediol diglycidyl ether) and hardener (isophorone diamine and 4,7,10-Trioxa-1,13-tridecanediamine) was studied by monitoring changes in glass transition temperature using DSC. Results were discussed using the DiMarzio's approach in which parameters are estimated from an additive group contribution. This theory allowed a fair assessment of Tg values for unaged networks. During oxidation, epoxy networks were shown to undergo chain scissions occurring in great part in hydroxypropyl ether and isophorone groups. However, the exploitation of Tg changes showed the coexistence and even the predominance of crosslinking in materials having linear aliphatic segments. The DiMarzio's approach was used to discuss the possibility of intramolecular cyclization or intermolecular crosslinks which were shown to predominate. Crosslinks were tentatively justified from a mechanistic point of view and quantified depending on experimental conditions.

Hydrolytic and thermal oxidative degradation behavior of thermotropic aromatic–aliphatic copolyesters

In this study, the hydrolytic and thermal oxidative degradation behavior of thermotropic aromatic–aliphatic copolyesters based on 4-hydroxybenzoic acid (HBA), 4-hydroxy-3-methoxybenzoic acid (VA), poly(butylene terephthalate) (PBT) and lactic acid (LA) have been investigated. The hydrophilicity and alkaline hydrolytic degradation rate of copolyesters increased with increasing LA contents. FTIR, DSC and TG results suggested that breakage of molecular chain mainly took place on aliphatic segments and also amorphous part. SEM analysis indicated the hydrolytic degradation followed surface corrosion mechanism. The dynamic TG results showed that all copolyesters exhibit total mass loss and two degradation stages under air atmosphere. The thermal oxidative degradation kinetics were evaluated by Kissinger and KAS method. The dependence of E values on conversion α has been observed in selected conversion range for all copolyesters, indicating complex degradation reaction existed.

Total synthesis of (3R,5R) and (3R,5S)-sonnerlactones

In this Letter, an enantioselective synthesis of (3R,5R)-sonnerlactone and (3R,5S)-sonnerlactone have been described. Stereochemistry at C-5 position was fixed using a suitable proline catalyzed reaction during the synthesis of aliphatic segment. To accomplish this target, Mitsunobu reaction for inversion of a stereocentre and ring-closing metathesis (RCM) for macrocyclic ring formations have been applied as key transformations.

An enantiocontrolled entry to the tricyclic polar segment of (+)-fusarisetin A

The tricyclic polar segment of fusarisetin A, designed for preparing analogues for structure–activity relationship studies of the aliphatic segment thereof, has been constructed in an enantiocontrolled manner, featuring the Yamamoto asymmetric epoxidation of a homoallylic alcohol, C3-selective ring-opening of a 3,4-epoxy alcohol, stereocontrolled merger of a γ-lactone with Garner’s counterpart, and ruthenium-catalyzed ring-closing metathesis.

A multiscale approach to model hydrogen bonding: The case of polyamide

We present a simple multiscale model for polymer chains in which it is possible to selectively remove degrees of freedom. The model integrates all-atom and coarse-grained potentials in a simple and systematic way and allows a fast sampling of the complex conformational energy surface typical of polymers whilst maintaining a realistic description of selected atomistic interactions. In particular, we show that it is possible to simultaneously reproduce the structure of highly directional non-bonded interactions such as hydrogen bonds and efficiently explore the large number of conformations accessible to the polymer chain. We apply the method to a melt of polyamide removing from the model only the degrees of freedom associated to the aliphatic segments and keeping at atomistic resolution the amide groups involved in the formation of the hydrogen bonds. The results show that the multiscale model produces structural properties that are comparable with the fully atomistic model despite being five times faster to simulate.

Synthesis and characterization of adipic acid/polyethylene glycol/poly(ethylene terephthalate) copolyester fiber

A series of aliphatic/aromatic copolyesters that contained different amounts of aliphatic segments, constructed from adipic acid (AA, 0∼0.117 mole ratios), were synthesized. The structure of each copolymer was confirmed by 1H nuclear magnetic resonance. The molecular weight was determined directly by gel permeation chromatography and indirectly by the intrinsic viscosity. The results of thermal tests revealed that both melting temperature ( T m) and crystallization temperature ( T c) decreased as the aliphatic segment content increased. The glass transition temperatures ( T g) that were determined by dynamic mechanical analysis followed the same trend as did T m. Moreover, the thermal stability, determined from thermogravimetric analysis, declined as polyethylene glycol (PEG) and AA were incorporated into the poly(ethylene terephthalate) (PET) main chains. All of the polymers that were synthesized herein were spun into fibers and then physically characterized. The tenacity of the fibers decreased as the soft-segment content increased. The crystalline structures, revealed by wide-angle X-ray scattering, indicated that the crystallinity decreased with increasing AA content because of the reduction of regularity of the PET chains. Most importantly, the tests that were carried out on the knitted fabric demonstrated that the moisture regain and cool feeling ( qmax) of the copolymer fabrics were better than those of fabrics that comprised neat PET chains, owing to the incorporation of soft PEG segments. Finally, the copolymer fabric exhibited better hydrolysis and enzymatic degradation than did neat PET fabric.

Surface modification of lignosulfonates for reinforcement of styrene–butadiene rubber compounds

ABSTRACTIn this study, surface modification of lignosulfonates (LSs) was investigated for potential reinforcement of styrene–butadiene rubber compounds. Lignins are naturally occurring amorphous, highly branched polymers consisting of aromatic and aliphatic segments with polar functional groups such as hydroxyl, methoxy, carbonyl, and carboxyl. The polarity and hydrophilic nature render lignin incompatible with nonpolar rubber materials. In this study, cyclohexylamine (CA) modification of LS was evaluated for enhancement of compatibility with rubber via proton transfer and hydrogen bonding interactions. X‐ray photoelectron spectroscopy data confirm attachment of CA onto the surface of LS. The cure and scorch times of rubber compounds were shortened, and the crosslink density enhanced with an increase of the amount of CA in modified LS. The tensile strength at break increased by almost 45%; the 100% modulus and elongation at break also showed significant improvements. The values of storage modulus and loss tangent increased by 13% and 18%, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40123.

Degradation of aliphatic and aliphatic–aromatic co-polyesters by depolymerases from Roseateles depolymerans strain TB-87 and analysis of degradation products by LC-MS

The degradation activities of bacterium, Roseateles depolymerans TB-87 and its depolymerases Est-H and Est-L against aliphatic as well as aliphatic–aromatic co-polyesters, were investigated. Strain TB-87 and its enzymes exhibited an ability to degrade aliphatic and aliphatic–aromatic co-polyesters. Monomers produced as a result of degradation of aliphatic polyesters [poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBSA)] as well as aliphatic–aromatic co-polyester [poly(butylene succinate/terephthalate/isophthalate)-co-(lactate) (PBSTIL) by depolymerases Est-H and Est-L were investigated by liquid chromatography mass-spectrometry (LC-MS). Some common monomers like succinic acid and 1,4-butanediol were detected besides adipic acid and terephthalic/isophthalic acids as degradation products from PBSA and PBSTIL, respectively, whereas lactic acid was not detected. The succinic acid monomer was detected prior to adipic acid as a result of degradation of PBSA. The enzymes depolymerized PBS also into respective monomers. The analysis of PBSTIL degradation products revealed that enzymes easily degraded aliphatic segments as compared to aromatic segments and resulted in production of succinic acid prior to terephthalic and isophthalic acid. On the basis of these results, we speculate that both the enzymes Est-H and Est-L, attacked succinic acid segments (BS) first instead of adipic acid (BA) and terephthalic/isophthalic acid (BT or BI) segments of PBSA and PBSTIL, respectively. It is concluded from the results that R. depolymerans strain TB-87 can depolymerize aliphatic as well as aliphatic–aromatic co-polyesters; therefore, its enzymes can be applied in the process of biochemical monomer recycling.

Synthesis of poly(3,4-ethylenedioxythiophene) nanoparticles via chemical oxidation polymerization

Poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles were synthesized via chemical oxidation polymerization using 3,4-ethylenedioxythiophene as the starting monomer and ammonium peroxydisulfate (APS) as the oxidant. The effects of APS concentration, surfactant concentration and type of surfactant, namely dodecylbenzenesulfonic acid and sodium dodecylsulfate, were investigated. Distinct particle shapes were obtained: irregular, raspberry agglomerate, coralliform, orange-peel, globular and plum shapes. The particle sizes and the electrical conductivity are in the ranges 60 to 900 nm and <1 to 153 S cm−1, respectively, depending on the polymerization conditions. PEDOT synthesis in the absence of a surfactant yields a smaller particle size because a larger amount of initiator induces lower molecular weights and smaller PEDOT particles. The smaller PEDOT particles correspond to higher electrical conductivity because of the larger surface areas for electron transfer and a smaller amount of obstructing surfactant aliphatic segments. Moreover, particle size and shape can be varied, depending on surfactant type and concentration which dictate the micellar shapes in the polymerization reaction. This work is focused on the tailor-made PEDOT shape and property relationship under synthesis conditions where several shapes have not been previously seen. © 2013 Society of Chemical Industry

Structure-property correlation of bromine substitution in polyimides

The influence of bromine substitution in polyimides onto physical properties is systematically investigated for the first time. A series of comparable polyimides with and without bromine substituents was synthesized and characterized. Thus, different aromatic or aliphatic diamines containing various flexible linkages were reacted with two analogous dianhydrides, from which one contains tetrabromo substituted phenylene rings. The structure of monomers and polymers was confirmed by infrared spectroscopy and proton nuclear magnetic resonance. The measurements showed that the bromine substitution did not significantly affect the thermal and dielectric properties of the corresponding polymers when compared to related structures. All polyimides exhibited enhanced solubility in polar and in less polar solvents. The introduction of bromine substituents led to the increase of glass transition temperature, being in the range of 147–274 °C for polymers containing only aromatic rings, and in the domain of 72–110 °C for polymers containing aliphatic segments. Also, by the introduction of bromine units thermal stability slightly decreased for the corresponding polymers, with initial decomposition temperature being in the range of 410–510 °C for polymers having only aromatic rings, and in the domain of 355–400 °C for polymers having aliphatic segments. The values obtained for dielectric constant, dielectric loss and activation energy of sub-glass relaxations for the polymer containing bromine units are slightly higher than those of polyimides without substituted phenylene rings.

High performance bismaleimide resins modified by novel allyl compounds based on polytriazoles

New poly(1,2,3-triazole)s functionalized with allyl groups were prepared by the 1,3-cycloaddition reaction (click reaction) of azido-imides to bispropargyl monomers containing allyl groups. The copolymers of 4,4'-bismaleimidodiphenylmethane with allylated polytriazoles were prepared and their properties investigated. Modified bismaleimide resins had excellent processing compared with neat bismaleimides, especially improved olubility and faster thermal polymerization rate. In addition, the new cured systems had good thermal and dielectric properties (dielectric constant at 1 kHz ranged between 3.09 and 3.39, except the polymer with aliphatic segment instead of the imide group that had a higher constant, namely 4.6).