Hydrogen Bonds and FTIR Peaks of Polyether Polyurethane-Urea

2019 ◽  
Vol 815 ◽  
pp. 151-156
Author(s):  
Xu Zhao ◽  
Yu Hong Qi ◽  
Ke Jiao Li ◽  
Zhan Ping Zhang
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Steric Effect ◽  
Electronic Effect ◽  
Theoretical Foundation ◽  
Microphase Separation ◽  
Ether Linkage ◽  
Proton Donors ◽  
Hard Segments ◽  
Degree Of Order

Various types of hydrogen bonds exist in polyether polyurethane, polyurethane-urea and polyurea (PUA) and can cause microphase separation. The morphology, properties and applications of polyether PUA are determined by the microphase separation. All kinds of hydrogen bonds make it difficult to assignments of Fourier transform infrared spectroscopy (FTIR) peaks of ether linkage, amine and carbonyl group. This affects the calculation of the hydrogen bonding degree of the hard segments for estimating the degree of microphase separation. This paper summarized hydrogen bonding structures between proton donors and proton acceptors. By analyzing the influence of electronic effect, steric effect, various types of hydrogen bonds and the degree of order of hydrogen bonding on infrared peaks, the relationships between hydrogen bonding structures and infrared peaks are established. Lay the theoretical foundation for evaluating the degree of microphase separation by FTIR method.

Basicité de liaison hydrogène de formamidines substituées sur l'azote imino

1992 ◽  
Vol 70 (8) ◽  
pp. 2203-2208 ◽  
Author(s):  
Ewa D. Raczyńska ◽  
Christian Laurence ◽  
Michel Berthelot
Keyword(s):  
Hydrogen Bonding ◽  
Nitrogen Atom ◽  
Hydrogen Bonds ◽  
Frequency Shift ◽  
Field Effect ◽  
Formation Constant ◽  
Steric Effect ◽  
Imino Nitrogen ◽  
Alkyl Groups ◽  
Electron Withdrawing Substituents

The basicity of the hydrogen bonds of formamidines 1–19 was measured by means of the formation constant KHB of their complexes with p-fluorophenol and the frequency shift Δν(OH) of methanol hydrogen-bonded to 1–19. The study of the ν(C=N) band shows that hydrogen bonding takes place with the imino nitrogen atom. On the hydrogen-bonding basicity scale, the formamidines appear to be more basic than the corresponding amides and pyridines, and as basic as the imidazoles. The field effect of electron-withdrawing substituents and the steric effect of bulky alkyl groups on the imino nitrogen atom markedly decrease the hydrogen-bonding basicity.

scholarly journals Hydrogen Bonds: Raman Spectroscopic Study

2021 ◽  
Vol 22 (10) ◽  
pp. 5380
Author(s):  
Boris A. Kolesov
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Spectroscopic Study ◽  
Raman Spectra ◽  
Temperature Region ◽  
Vibrational Frequency ◽  
Chemical Compounds ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Proton Dynamics

The work outlines general ideas on how the frequency and the intensity of proton vibrations of X–H×××Y hydrogen bonding are formed as the bond evolves from weak to maximally strong bonding. For this purpose, the Raman spectra of different chemical compounds with moderate, strong, and extremely strong hydrogen bonds were obtained in the temperature region of 5 K–300 K. The dependence of the proton vibrational frequency is schematically presented as a function of the rigidity of O-H×××O bonding. The problems of proton dynamics on tautomeric O–H···O bonds are considered. A brief description of the N–H···O and C–H···Y hydrogen bonds is given.

scholarly journals Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4705
Author(s):  
Boer Liu ◽  
Xi Chen ◽  
Glenn A. Spiering ◽  
Robert B. Moore ◽  
Timothy E. Long
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Microphase Separation ◽  
Triblock Copolymers ◽  
Random Copolymer ◽  
Thermomechanical Properties ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Central Block ◽  
Quadruple Hydrogen Bonding

This work reveals the influence of pendant hydrogen bonding strength and distribution on self-assembly and the resulting thermomechanical properties of A-AB-A triblock copolymers. Reversible addition-fragmentation chain transfer polymerization afforded a library of A-AB-A acrylic triblock copolymers, wherein the A unit contained cytosine acrylate (CyA) or post-functionalized ureido cytosine acrylate (UCyA) and the B unit consisted of n-butyl acrylate (nBA). Differential scanning calorimetry revealed two glass transition temperatures, suggesting microphase-separation in the A-AB-A triblock copolymers. Thermomechanical and morphological analysis revealed the effects of hydrogen bonding distribution and strength on the self-assembly and microphase-separated morphology. Dynamic mechanical analysis showed multiple tan delta (δ) transitions that correlated to chain relaxation and hydrogen bonding dissociation, further confirming the microphase-separated structure. In addition, UCyA triblock copolymers possessed an extended modulus plateau versus temperature compared to the CyA analogs due to the stronger association of quadruple hydrogen bonding. CyA triblock copolymers exhibited a cylindrical microphase-separated morphology according to small-angle X-ray scattering. In contrast, UCyA triblock copolymers lacked long-range ordering due to hydrogen bonding induced phase mixing. The incorporation of UCyA into the soft central block resulted in improved tensile strength, extensibility, and toughness compared to the AB random copolymer and A-B-A triblock copolymer comparisons. This study provides insight into the structure-property relationships of A-AB-A supramolecular triblock copolymers that result from tunable association strengths.

scholarly journals Impact of Macrodiols on the Morphological Behavior of H12MDI/HDO-Based Polyurethane Elastomer

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2060
Author(s):  
Shazia Naheed ◽  
Mohammad Zuber ◽  
Mahwish Salman ◽  
Nasir Rasool ◽  
Zumaira Siddique ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Chain Length ◽  
Microphase Separation ◽  
Soft Segment ◽  
Group Identification ◽  
Degree Of Crystallinity ◽  
Polyurethane Elastomers ◽  
Hard Segments ◽  
Morphological Behavior

In this study, we evaluated the morphological behavior of polyurethane elastomers (PUEs) by modifying the soft segment chain length. This was achieved by increasing the soft segment molecular weight (Mn = 400–4000 gmol−1). In this regard, polycaprolactone diol (PCL) was selected as the soft segment, and 4,4′-cyclohexamethylene diisocyanate (H12MDI) and 1,6-hexanediol (HDO) were chosen as the hard segments. The films were prepared by curing polymer on Teflon surfaces. Fourier transform infrared spectroscopy (FTIR) was utilized for functional group identification in the prepared elastomers. FTIR peaks indicated the disappearance of −NCO and −OH groups and the formation of urethane (NHCOO) groups. The morphological behavior of the synthesized polymer samples was also elucidated using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The AFM and SEM results indicated that the extent of microphase separation was enhanced by an increase in the molecular weight of PCL. The phase separation and degree of crystallinity of the soft and hard segments were described using X-ray diffraction (XRD). It was observed that the degree of crystallinity of the synthesized polymers increased with an increase in the soft segment’s chain length. To evaluate hydrophilicity/hydrophobicity, the contact angle was measured. A gradual increase in the contact angle with distilled water and diiodomethane (38.6°–54.9°) test liquids was observed. Moreover, the decrease in surface energy (46.95–24.45 mN/m) was also found to be inconsistent by increasing the molecular weight of polyols.

Viscoelastic Behavior of Segmented Elastomers

1967 ◽  
Vol 40 (4) ◽  
pp. 1105-1110 ◽  
Author(s):  
Stuart L. Cooper ◽  
Arthur V. Tobolsky
Keyword(s):  
Hydrogen Bonding ◽  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscoelastic Behavior ◽  
Temperature Transition ◽  
Hydrogen Bonding Interactions ◽  
Structural Nature ◽  
Hard Segments

Abstract Viscoelastic behavior of linear segmented elastomers was examined. The unusual properties found in spandex systems are also observable in hydrocarbon block co-polymers, indicating that hydrogen bonding interactions are perhaps not essential. Low temperature properties of segmented systems are governed by the structural nature of the associated flexible segments, which determines the value of the major glass transition temperature (Tg). It appears that an association of the hard segments provides a broad temperature range of enhanced rubbery modulus. This occurs between the major Tg and a secondary high temperature transition.

2-Hydroxy-3-methoxybenzaldehyde (pyridinium-4-ylcarbonyl)hydrazone chloride hemihydrate

2006 ◽  
Vol 62 (5) ◽  
pp. o2043-o2044 ◽  
Author(s):  
Shao-Wen Chen ◽  
Han-Dong Yin ◽  
Da-Qi Wang ◽  
Xia Kong ◽  
Xiao-Fang Chen
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Compound C

The crystal structure of the title compound, C14H14ClN3O3 +·Cl−·0.5H2O, exhibits O—H...O, C—H...O, C—H...Cl, N—H...Cl and O—H...Cl hydrogen bonds. The chloride anions participate in extensive hydrogen bonding with the aminium cations and link molecules through multiple N—H+...Cl− interactions.

A small-angle X-ray scattering study of microphase separation transition of polyurethanes: Effect of hard segments

1995 ◽  
Vol 2 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Kung Linliu ◽  
Show-An Chen ◽  
T. L. Yu ◽  
Tsang-Lang Lin ◽  
Chih-Hao Lee ◽  
...  
Keyword(s):  
Small Angle ◽  
Microphase Separation ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Hard Segments ◽  
Ray Scattering
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