Papers by Keyword: Hydrogen Bonding

Abstract: The protic ionic liquids (PILs) comprising with N-2-ethylhexylethylenediaminium cation (HEtHex⁺) and bis (trifluoromethanesulfonate) imide anion (TFSA^-) forming [HEtHex][TFSA] which has two amines in the polar group and available to absorbs acid gases such as CO₂ and SO₂. In order to study the CO₂/SO₂ absorption mechanism of [HEtHex][TFSA], the stable configurations of [HEtHex][TFSA]-nCO₂ (n=1, 2, 3, 4) and [HEtHex][TFSA]-nSO₂ (n=1, 2, 4, 6) are investigated using the density functional theory at the M06-2X/6-311G (d, p) level, then the interaction energy, molecular vibration frequency, second-order perturbation energy, electron density and Laplace value are calculated and analysed for the most stable configurations. The results show that N–H^...O type weak or medium hydrogen bonding are mainly formed between [HEtHex][TFSA] and CO₂/SO₂ molecules. The hydrogen bonding interaction is stronger for [HEtHex][TFSA]-nSO₂ comparing with [HEtHex][TFSA]-nCO₂ and increases with increasing the number of CO₂/SO₂ molecules.

Abstract: Shape memory polyurethane (SMPU) is a very versatile material that has a broad array of applications. The selection of soft segments and hard segments play critical roles in determining the structure-property behaviors of SMPU. This research was conducted to evaluate the role of distinct types of diisocyanate on the final properties of polyurethane (PU). Palm kernel oil polyol (PKO) based PU were produced by using two-step bulk polymerization method with variations of diisocyanates. Isophorone diisocyanate (IPDI), 4,4-methylenebis (cyclohexyl isocyanate) (HMDI) and hexamethylene diisocyanate (HDI) were used in the preparation of PU and the soft segment crystallinity, thermal and shape memory properties of the PU were evaluated. Based on the analyses, it was found that different types of diisocyanate and combination of diisocyanates had huge impact on the properties of the synthesized PU. The Fourier transformation infrared (FTIR) analysis revealed that IPDI based PU achieved the highest hydrogen bonding index value which promoted the phase separation. This is in accordance with differential scanning calorimetric (DSC) and x-ray diffraction (XRD) analysis which showed that IPDI based PU exhibited crystalline soft phase, hence resulted in an excellent shape fixity behavior. On the other hand, HDI and HMDI based polyurethane prepared showed absence of crystalline soft phase based on the DSC thermogram and XRD diffractogram. These results suggest the phase mixing phenomenon between soft and hard segments which contributed to low shape memory behavior of the resulting polyurethane.

Abstract: The purpose of this study is the development and characterizations of novel polyvinyl alcohol (PVA)/polyvinyl pyrolidone (PVP) hydrogel blends. Different mixtures of the two polymeric solutions leaded to several hydrogels that were further characterized using X-ray difraction (XRD), differential thermal and thermogravimetric analysis (DTA/TGA) and Fourier transform infrared spectroscopy (FTIR). The influence of the polymer type on hydrogel hydration was also studied, by observing and comparing the samples after drying and rehydration in bidistilled water. The results revealed the maintenance of the amorphous character of the hydrogels after rehydration as well as a higher softening and decomposition temperature in direct relation with the increase of PVA content. The best wetting and swelling results were also given by the hydrogel with the highest PVA content prepared at pH 6.

Abstract: Results of the study of Mn (II)/Mn (III)-NEt₃ complex self-assembled with the formation of hydrophobic core are considered in terms of hydrogen bonding between the ligands of manganese octahedral complexes. It is found that the hydrogen bonding plays important role in spin-spin interaction of the coupled Mn-aquacomplexes. Number of H₂O molecules in the shell of the latter is suggested to estimate according to the peak-to-peak width (ΔB_pp) of the broadened ESR pattern.

Abstract: A new molecular complex constructed by fumaric acid with piperazine has been prepared and characterized by single crystal X-ray diffraction. The number of fumaric acid involved in the complex equals to the number of N-protonated binding sites in the piperazine molecule. The structure contained infinite 1D supramolecular chains held together by robust, primary O–H•••O charge-assisted hydrogen bonds, and the 2D sheet like pattern constructed via the expected carboxyl-piperazine heterosynthon. Persistent N–H•••O interactions were found to play an important role in the formation of the final 3D arrays. The five dominant supramolecular synthons in the crystal structure are the heteromeric carboxylic acid•••piperazine hydrogen bond interactions, which prevail in the presence of widely differing chemical functionalities. Thermal stability of the compound has been investigated by thermogravimetric analysis (TGA) of mass loss.

Abstract: In this work, the physicochemical property and its Effect of hydrous amorphous cellulose has been studied using molecular dynamics. Both intramolecular and intermolecular hydrogen bonds in cellulose molecules decrease with increasing water content, directly leading to the decline of cellulose cohesive energy density, solubility parameters, and mechanical parameters. High water content in amorphous cellulose gives bigger interchain distance of cellulose molecules, indicating that the intermolecular interaction of cellulose molecules is weakened greatly by water.

Abstract: In this research, a regioregular poly (3-alkylthiophene) derivative had been synthesized via the post-polymerization functionalization, poly (3-hexylamine thiophene), which are soluble in water and water miscible solvents such as methanol, DMSO. The suitable energy level, good thermal stability and water/alcohol solubility of polymers which promising applied in polymer solar cells and processed by water or environmental-friendly solvents. In blend of functionalization polymers and fullerene derivative potassium [6,6]-phenyl-C₆₁-butyrate shows significant UV absorption decay phenomenon and occur precipitates follow with time increase. To further investigate the mechanism of composite, FT-IR analysis and TEM investigate were used, the polymer would be bonded with carboxyl of fullerene derivative via hydrogen bonding in the carboxyl region and TEM images demonstration the mixture that be able to self-assembly a interpenetrating network composite.

Abstract: A series of waterborne polyurethane (WPU) with different soft segment structures were sythesised, and the effects of the structure and molecular weight of the soft segment on the degree of PU microphase separation were evaluated by the infrared spectroscopy (FTIR) computer peak fitting. The experiment results indicated that phase separation between hard and soft segments of poly (ether–urethane) was more significant than poly (ester–urethane), based on the qualitative analysis on the N–H stretching region of the FTIR spectrum. And the qualitative analysis on the carbonyl stretching region showed that PU with lower soft segment molecular weight had a higher relative amount of hard segment, and possesses higher microphase separation degree. The addition of polyether soft segment PEG had an internal plasticization by actuating the PCD molecular chain. Therefore, it becomes easier for PU to conduct structure adjustment and increased the phase separation degree.

Abstract: Herein we report the first example of benzene-1,3,5-tricarboxamide bearing hydrophobic aminododecane side chains (1) which spontaneously forms supramolecular network by a hydrogen bonding interaction. The compound 1 was synthesized by Schotten-Baumann reaction of 1,3,5-benzenetricarbonyl trichloride and 1-aminododecane in the presence of N,N-diisopropylethylamine. Nuclear Magnetic Resonance (NMR), Mass Spectrometry (MS), and Fourier Transform Infrared (FTIR) spectroscopies have proved the successful synthesis of 1 in 93% as white powder solid. The supramolecular organization was successfully utilized for sensing of nitrate anions by deformation of the hydrogen bonding to form inactive nitroso groups.

Abstract: Biomass cushioning packaging material has been gaining attention in the properties of the materials because of biodegradable and green environmental protection, and the starch plastics play an important role. Urea, formamide, glycerol, ethylene glycol four material compounded with starch respectively, for the purpose to forming hydrogen bonds by the test in this paper, the ability to hydrogen bond with the starch has been observed by infrared spectrum analysis. The results showed that urea, formamide as strong electronegative group stronger binding, glycerol and ethylene glycol are more preferably to form hydrogen bonds with the starch because of more hydroxyl group content.