Synthesis and characterization of novel aromatic polyamides derived from 2,2′‐bis(p‐phenoxyphenyl)‐4, 4′‐diaminodiphenyl ether

BACKGROUND: Wholly aromatic polyamides (aramids) are high‐performance polymeric materials with outstanding heat resistance and excellent chemical stabilities due to chain stiffness and intermolecular hydrogen bonding of amide groups. Synthesis of structurally well‐designed monomers is an effective strategy to prepare modified forms of these aramids to overcome lack of organo‐solubility and processability limitations. RESULTS: A novel class of wholly aromatic polyamides was prepared from a new diamine, namely 2,2′‐bis(p‐phenoxyphenyl)‐4,4′‐diaminodiphenyl ether (PPAPE), and two simple aromatic dicarboxylic acids. Two reference polyamides were also prepared by reacting 4,4′‐diaminodiphenyl ether with the same comonomers under similar conditions. M?_w and M?_n of the resultant polymers were 8.0 × 10⁴ and 5.5 × 10⁴ g mol^?1, respectively. Polymers resulting from PPAPE exhibited a nearly amorphous nature. These polyamides exhibited excellent organo‐solubility in a variety of polar solvents and possessed glass transition temperatures up to 200 °C. The 10% weight loss temperatures of these polymers were found to be up to 500 °C under a nitrogen atmosphere. The polymers obtained from PPAPE could be cast into transparent and flexible films from N,N‐dimethylacetamide solution. CONCLUSION: The results obtained show that the new PPAPE diamine can be considered as a good monomer to enhance the processability of its resultant aromatic polyamides while maintaining their high thermal stability. The observed characteristics of the polyamides obtained make them promising high‐performance polymeric materials. Copyright © 2009 Society of Chemical Industry     

One-dimensional coordination polymers based on first-row transition metals: A solid-state study of weak backbone interactions

We present further data on the solid-state structures of one-dimensional coordination polymers based upon dipositive transition metal hexafluoro-acetylacetonate (hfacac) complexes. A variety of linking subunits are employed in order to investigate and probe the relatively weak interactions that make up the backbones of these polymers. Reported in this study are metal complexes containing manganese, zinc, copper, and cobalt and a range of donor building blocks encompassing an array of bonding motifs, including pyridyl—metal, pyridyl(N-oxide)—metal, and hydrogen bonding. The specific linkers utilized are 4,4′-dipyridyl N,N′-dioxide hydrate, 2,5-bis(4-ethynylpyridyl)furan, 4,4′-trimethylenedipyridine, and trans-1-(2-pyridyl)-2-(4-pyridyl)-ethylene. A detailed discussion of the products is presented, as is a comparison to known compounds of a similar nature. All compounds are characterized via single-crystal X-ray diffraction and elemental analysis for the bulk of the sample.     

Steric Modulation of the Porphycene System by Alkyl Substituents: 9,10,19,20-Tetraalkylporphycenes

Porphycene ( 2 ), a planar structural isomer of porphyrin ( 1 ) recognized and synthesized only recently, exhibits short N … N distances allowing exceptionally strong N-H … N hydrogen bonds to be formed. Although the N₄-coordination hole of 2 is smaller than that of 1 , the new tetrapyrrolic macrocycle is capable of complexation with a broad spectrum of metal ions to give the respective metalloporphycenes. In accord with model considerations, both N-H … N hydrogen bonding and complexation of 2 may be modulated by peripheral alkyl groups through changes in the geometry of the porphycene skeleton arising from non-bonded repulsions between the substituents. In this publication are delineated some of the consequences of structural variation of 2 by introduction of alkyl groups at the 9,10,19,20-positions.     

Synthesis and properties of hydroxyapatite nanorod‐reinforced polyamide 6 nanocomposites

BACKGROUND: Polyamide 6 (PA6)/hydroxyapatite (HA) nanocomposites, which combine the bioactivity and biocompatibility of HA and the excellent mechanical performance of PA6, have emerged as new biomaterials with potential applications in the clinical setting. It has been shown that these nanocomposites show good similarity to natural bone in terms of chemistry and mechanical properties. RESULTS: In this study, highly crystallized hydroxyapatite nanorods (HANR) were used to fabricate PA6/HA nanocomposites via in situ hydrolytic ring‐opening polymerization of ε‐caprolactam. The effect of the HANR on the thermal stability, crystallization behavior and hydrogen bonding of PA6 was investigated using thermogravimetric analysis, differential scanning calorimetry and Fourier transform infrared (FTIR) spectroscopy, respectively. It was found that HANR can obviously increase the crystallization temperature and decrease the degree of supercooling. In addition, the thermal degeneration temperature of PA6 is also increased by the incorporation of HANR. FTIR analysis of the hydrogen bonded N? H stretching vibration revealed that, with increasing HANR loading, the hydrogen bonded N? H stretching band shifts to higher frequency and decreases in intensity. CONCLUSION: The thermal stability and crystallization ability of PA6 are improved considerably by the incorporation of HANR. However, the hydrogen bonding strength is weakened and the degree of ordering of hydrogen bonding is reduced by the incorporation of HANR, which can be explained by the formation of hydrogen bonds at the interface between ? OH groups of HANR and the ? N? H or ? C?O groups of PA6. Copyright © 2009 Society of Chemical Industry     

Absorption of water by proteins and related compounds

Isotherms have been obtained for the absorption of water by proteins and polyamides and by simple amides closely related to the repeat chemical unit of the polymers. The differential heat of absorption of water at zero water content has also been determined for these substances, from isosteres and from heats of mixing. In addition the nature of the hydrogen bonding of water to these compounds has been investigated by infrared spectroscopic methods. The large differences found between the heats of absorption by the polymers and the simple model compounds are discussed.     

聚氨酯红外光谱氢键化谱带的归属与定量分析

聚氨酯（ＰＵ）红外光谱图中与氢键化有关的基本谱带已有归属，但最近一些研究工作表明这些谱区的复杂性。胺基区中谱带数目多、重叠严重、摩尔吸光系数随波数的变化较大，用以分析ＰＵ的氢键化并不理想。羰基区中多重氢健化谱带的存在已得到确认，这些谱带的摩尔吸光系数差别不大，适宜于氢键化分析。用醚键区来分析ＰＵ的氢键化要慎重。由于多重氢键化谱带的存在，ＰＵ中的氢键解离平衡必然是一个多步平衡过程，求取氢键解离平衡的     

Aromatic polyamides bearing ether and isopropylidene or hexafluoroisopropylidene links in the main chain

Two multiring, flexible dicarboxylic acids, 4,4'-[isopropylidenebis(1,4-phenylene)dioxy] dibenzoic acid (3) and 4,4'-[hexafluoroisopropylidenebis(1,4-phenylene)dioxyldibenzoic acid (3-F), were synthesized through the nucleophilic fluorodisplacement ofp-fluorobenzonitrile by the dipotassium bisphenolates of the corresponding bisphenol precursors followed by alkaline hydrolysis. Two series of aromatic polyamides 5_a–k and 5_a–k-F containing both ether and isopropylidene or hexafluoroisopropylidene linkages between phenylene units were prepared by direct polycondensation of diacids 3 and 3-F, respectively, with various aromatic diamines using triphenyl phosphite and pyridine as condensing agents in aN-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride. The resulting polyamides of 5 and 5-F series have inherent viscosities of 0.92–1.29 dL/g and 0.60–0.92 dL/g, respectively. Most of these polymers are amorphous in nature, are soluble in polar solvents such as NMP,N,N-dimethylacetamide (DMAc), andN,N dimethylformamide (DMF), and can afford tough and flexible films by solution casting. Differential scanning calorimetry shows T_gs ranging from 175 to 239 °C for the 5 series polyamides and ranging from 172 to 267 °C for the 5-F series polymers. Both classes of polyamides show good thermal stability, with the 5-F series polyamides being more stable.     

Removal of N‐methylpyrrolidone hydrogen‐bonded to polyaniline free‐standing films by protonation–deprotonation cycles or thermal heating

Free‐standing films of polyaniline (PANI), in an emeraldine base state, prepared by evaporation of polymer solutions in N‐methylpyrrolidone (NMP) retain solvent even under dynamic vacuum drying as indicated by transmission Fourier transform infrared (FTIR) spectroscopy, where a band at 1670 cm^?1 is clearly observed. Upon protonation–deprotonation cycles in aqueous media the weight of the dry base film decreases indicating gradual loss of NMP. Transmission FTIR spectra shows also the washing out of NMP with a clear decrease in intensity of the hydrogen‐bonded >C?O stretching band (1670 cm^?1) of NMP. During this process the bands between 3500 and 3200 cm^?1, assigned to >N? H stretching in the PANI backbone, change intensity suggesting that intermolecular hydrogen‐bonded >N? H, with carbonyl oxygen of NMP, is replaced by free >N? H. This is clear evidence of specific interaction of NMP with the emeraldine base. A similar loss of NMP is observed during heating but evidence of polymer degradation is also present. A mechanism is proposed to account for the loss of hydrogen‐bonding ability upon protonation which requires delocalization of the radical cations in the protonated films. © 2001 Society of Chemical Industry     

Synthesis,characterization, and properties of novel fluorine containing aromatic polyamides

A series of novel fluorine containing aromatic polyamides were synthesized by the direct polycondensation of various fluorine containing aromatic diamines and commercially available 5‐t‐butyl isophthalic acid. These polyamides have good solubility in several organic solvents such as dimethylformamide, N,N‐dimethylacetamide, 1‐Methyl‐2‐pyrrolidone, dimethyl sulfoxide, and tetrahydrofuran. The synthesized polymers exhibited inherent viscosities up to 0.93 dL/g and M_w up to 1,52,000 with PDI of 2.49. The polyamides exhibited good thermal stability up to 489°C for 10% weight loss in nitrogen and high glass transition temperature up to 273°C. Dynamic mechanical analysis showed a very good retention of storage modulus up to the glass transition temperature. The tan δ peak value at 1 Hz was used to calculate the T_g and these values are in good agreement with differential scanning calorimetry data. The polyamide films were flexible with tensile strength up to 72 MPa, elongations at break up to 14%, and modulus of elasticity up to 1.39 GPa depending on the exact repeating unit structure. X‐ray diffraction measurements indicate that these polyamides are semicrystalline. Rheology study showed same trend of melt viscosity behavior with different shear rate for all polymers. Water absorption study indicates the hydrophobic nature of the polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Specific interactions in poly(styrene‐co‐2‐hydroxyethyl acrylate)/poly(styrene‐co‐N,N‐dimethylacrylamide) systems

Amphiphilic copolymers of poly(styrene‐co‐2‐hydroxyethyl acrylate) (SHEA) and poly(styrene‐co‐N, N‐dimethylacrylamide) (SAD) of different compositions were prepared by free radical copolymerization and characterized by different techniques. Depending on the nature of the solvent and the densities of interacting species incorporated within the polystyrene matrices, novel materials as blends or interpolymer complexes with properties different from those of their constituents were elaborated when these copolymers are mixed together. The specific interpolymer interactions of hydrogen bonding type and the phase behavior of the elaborated materials were investigated by differential scanning calorimetry (DSC) and Fourier transform infra red spectroscopy (FTIR). The specific interactions of hydrogen bonding type that occurred within the SHEA and within their blends with the SAD were evidenced by FTIR qualitatively by the appearance of a new band at 1626 cm^?1 and quantitatively using appropriate spectral curve fitting in the carbonyl and amide regions. The variation of the glass transition temperature with the blend composition behaved differently with the densities of interacting species. The thermal degradation behavior of the materials was studied by thermogravimetry. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Hydrogenated nitrile butadiene rubber and hindered phenol composite. II. Characterization of hydrogen bonding

This article reports on the relationship between the variation of hydrogen bonding and macroscopic properties of composites composed of hydrogenated nitrile butadiene rubber (HNBR) and 3,9‐bis {1,1‐dimethyl‐2 [β‐(3‐tert‐butyl‐4‐hydroxy‐5‐methylphenyl) propionyloxy] ethyl}‐2,4,8,10‐tetraoxaspiro [5,5]‐undecane (AO‐80). Hydrogen bonding of the composites was studied by Fourier‐transform infrared (FT‐IR) and ultraviolet (UV) spectroscopies. FT‐IR spectra at room temperature revealed that the stretching vibration peak of O? H and C?O of AO‐80 red shifted with increasing AO‐80 content, whereas that of C≡N of HNBR blue shifted only when the AO‐80 content exceeded 10 parts per 100 resin (phr). At elevated temperatures, the shift was the opposite for C?O and C≡N bands resulting from hydrogen bonding dissociation. In the UV spectra, the E₂ band of benzene ring of AO‐80 exhibited two peaks differing in shape. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

“Orientation induced memory effect” in polyamides and the relationship to hydrogen bonding

The influence of molecular orientation on the “memory effect” of polyamides was investigated by differential scanning calorimetry. Melt crystallization of undrawn and drawn polyamide 6 (N6) and polyamide 66 (N66) fibers showed no difference either in the rate of crystallization or crystallization temperature. We demonstrated that hydrogen bonding does not play a major role in melt crystallization kinetics of polyamides (N6 and N66), and the “memory effect” is only retained for polymers, including N6 and N66, because of insufficient time spent above the melting temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 772–775, 2003     

壳聚糖衍生物的红外光谱分析

合成了以下多种壳聚糖衍生物并测定了它们的红外光谱。这些衍生物是羧酸化壳聚糖 ,苯甲酰化壳聚糖 ,氰乙基壳聚糖 ,羟丙基壳聚糖 ,羟乙基壳聚糖 ,N -羧甲基化壳聚糖 ,壳聚糖的苯甲醛西佛碱 ,N -乙基壳聚糖 ,N -丁二酰化壳聚糖 ,N -顺丁烯二酰化壳聚糖 ,N -邻苯二甲酰化壳聚糖和N -乙酰化壳聚糖。观察到随壳聚糖脱乙酰度的增加 ,酰胺Ⅰ谱带移向低频 ,而酰胺Ⅲ谱带和醇羟基谱带移向高频 ,结果可用氢键的变化加以解释。脂肪族酰化壳聚糖的取代基长度对C =O位置影响很小 ,它们的C =O都能与邻近的N -H和O -H基生成相似的氢键。氰乙基壳聚糖的取代度影响了C -O谱带的位置 ,低取代的 1 0 70cm- 1 和 1 0 30cm- 1 双峰在高取代时被 1 0 61cm- 1 单峰所代替。通过IR测定 ,对丁二酰化壳聚糖和顺丁烯二酰化壳聚糖观察到含自由羧基端的线形取代 ,对邻苯二甲酰化壳聚糖 ,在反应程度较高时还出现环状取代。羧酰化壳聚糖、氰乙基壳聚糖和邻苯二甲酰化壳聚糖的取代度可分别用吸光度比A1 740 /A1 52 7,A2 2 4 9/A1 52 7和A1 71 2 /A1 391 测定     

Infrared spectroscopic studies of thermotropic polyamides

Summary Poly (3,3, 5,5-tetraethyldiphenylmethane-1, 18-octadecanedi carboxamide) (poly(TEDPM-ODDA)) and poly(diphenylmethane-1, 18-octadecanedicarboxamide) (poly(DPM-ODDA)) are newly synthesized and found mesomorphic phase between 493 and 502 K for the former and no mesomorphic phase for the latter by use of DSC measurements and polarizing microscope observation. In the IR spectra of enantiotropic mesomorphic poly(TEDPM-ODDA), the stepwise high frequency shift of the hydrogen-bonded N-H stretching vibration in crystalline-mesomorphic and mesomorphic-isotropic liquid phase transition suggest formation of the mesomorphic state due to balancing interchain hydrogen bonding and other interchain forces. On the contrary, nonmesomorphic poly(DPM-ODDA) the N-H bands shifts to higher frequency at melting to isotropic liquid at a stretch.     

Synthesis and characterization of novel Schiff‐base polyamides from copper/benzil bisthiosemicarbazone complexes

A new copper‐containing Schiff‐base diamine, benzil bis(thiosemicarbazonato)copper(II) (CuLH₄), was synthesized in two steps from benzil bisthiosemicarbazone (LH₆). The ligand LH₆ and the complex CuLH₄ were characterized with Fourier transform infrared spectroscopy, ¹H‐NMR, and elemental analysis. CuLH₄ was used to prepare novel polyamides. The low‐temperature solution polycondensation of the complex CuLH₄ with various aromatic and aliphatic diacid chlorides afforded copper‐containing Schiff‐base polyamides with inherent viscosities of 0.25–0.36 dL/g in N,N‐dimethylformamide (DMF) and 0.75 dL/g in H₂SO₄ at 25°C. The polyamides were generally soluble in a wide range of solvents, such as DMF, N,N‐dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, ethyl acetate, tetrachloroethane, hexamethylene phosphoramide, N‐methylpyrrolidone, and pyridine. Thermal analysis showed that these polyamides were practically amorphous, decomposed above 270°C, and exhibited 50% weight loss at and above 400°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of a novel amphiphilic polymer containing nucleobases in the self-organized nanospheres

A simple strategy to achieve molecular recognition in water is to make the polymers self-organized into nanospheres which could incorporate the functional groups containing hydrogen bonding sites into hydrophobic-lipophilic regions. A novel amphiphilic polymer, Poly(polyoxyethylene-600)-oxy-5-(6-(1-thymine)hexyl)) isophthaloyl (PPETHI), has been synthesized. The PPETHI polymer could self-organize into nanospheres in dilute aqueous solution, which were 150–300 nm in diameter as estimated by SEM. The isophthaloyl with side hexyl thymine of the polymer self-organized into hydrophobic regions and the PEG surrounded it. Molecular recognition between thymine in PPETHI polymer and adenine substrate has been studied by FT-IR. The FT-IR studies demonstrate that C₄=O of thymine has recognized with N-H of adenine through complementary nucleobases. It shows that the typical characteristic band at 3,352 cm⁻¹ of N-H stretching vibration of adenine shifted to 3,373 cm⁻¹ and the band at 1,685 cm⁻¹ of C₄=O of thymine shifted to 1,680 cm⁻¹. To confirm the formation of hydrogen bonds, the N-H band at 3,373 cm⁻¹ and C₄=O band at 1,680 cm⁻¹ have retrieved to 3,312 cm⁻¹ and 1,685 cm⁻¹ respectively upon heating to 115 °C or higher by means of variable temperature FT-IR. The formations of hydrogen-bonds between thymine in the polymer and adenine substrate in nanospheres were confirmed. It could enhance their interaction and loading capacity.     

Synthesis of N,N′-bis [(dialkoxyphosphinyl) methyl]-1,4-benzenediamines and the corresponding polymers

The title diamines were synthesized by condensation of 1,4-phenylenediamine with paraformaldehyde and a suitable phosphorus acid triester. The N,N′-dibenzoyl derivatives of the above compounds were also prepared. New flame-retardant polyamides were synthesized under various experimental conditions by condensation of these diamines with terephthaloyl dichloride. The polyamides produced have low viscosities. Blends with polystyrene (PS) have been made and their flammabilities determined.     

Application-relevant characterization of magnetron-sputtered carbon nitride films

Carbon nitride (CN_x) films were deposited onto Si substrates by radio frequency magnetron sputtering at nitrogen pressures up to 0.3 Pa (the resulting nitrogen concentration ranged from 32 to 41%). Their optical properties, structure and bonding were characterized by spectroscopic ellipsometry, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The films exhibit a behavior typical for disordered systems, and no known C₃N₄ structure was identified. A pronounced effect of the nitrogen partial pressure is found for the low pressure region. The presence of various types of CN bond, as well as of hydrogen and oxygen, is revealed. The complementarity of information inferred from Raman and IR spectra is discussed.     

Interpolymer interactions and miscibility in poly(n‐butyl methacrylate‐co‐methacrylic acid)/poly(styrene‐co‐N,N‐dimethyl acrylamide) blends

The miscibility of poly(n‐butyl methacrylate‐co‐methacrylic acid) containing 18 mol % methacrylic acid (BMAM‐18) and poly(styrene‐co‐N,N‐dimethyl acrylamide) containing 17 mol % N,N‐dimethyl acrylamide (SAD‐17) was investigated with viscometry, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The DSC analysis showed a single glass‐transition temperature for all the blends, indicating that these copolymers were miscible over the entire composition range. The glass‐transition temperatures of these blends were higher than those calculated with the additivity rule. This was characteristic of the presence of specific interactions. The interactions between BMAM‐18 and the tertiary amide of SAD‐17 were studied with FTIR spectroscopy, which revealed that hydrogen‐bonding interactions occurred between the hydroxyl groups of BMAM‐18 and the carbonyl amide of SAD‐17. A new band characterizing these interactions appeared around 1613 cm^?1. The quantitative results showed that the fraction of the associated amide increased with an increase in the amount of the acidic BMAM‐18 copolymer. Although BMAM‐18 and SAD‐17 led to homogeneous solutions in butan‐2‐one, as the concentration of N,N‐dimethyl acrylamide increased to 32 mol % [as within the poly(styrene‐co‐N,N‐dimethyl acrylamide) containing 32 mol % N,N‐dimethyl acrylamide], complexation occurred when this latter compound was mixed with BMAM‐18 in butan‐2‐one. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2717–2724, 2006