Carbon-13 NMR investigation of a poly(urethane-urea) system

Okamoto, David T.; Cooper, Stuart L.; Root, Thatcher W.

doi:10.1021/ma00029a009

Cited by 36 publications

(28 citation statements)

References 4 publications

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“…1 H and 13 C NMR experiments were performed on a Varian VXR-300S multinuclear spectrometer with 1 H and 13 C resonance frequencies of 300.0 and 78.2 MHz, respectively. In the MAS measurements, a Doty high-speed MAS probe was used.…”

Section: Solid-state Nmrmentioning

confidence: 99%

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Characterization of Local Structures in Flexible Polyurethane Foams by Solid-state NMR and FTIR Spectroscopy

Oka

Tokunaga

Masuda³

et al. 2006

Journal of Cellular Plastics

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The article examines the characterization of local structures in water-blown flexible polyurethane foams with various amine catalysts.In this study, the authors have applied solid-state nuclear magnetic resonance (NMR) relaxation, nuclear spin diffusion, and Fourier transform infrared (FTIR) microscope analysis on flexible polyurethane foams. Quantitative knowledge of the polymer structure and dynamics by these methods provides a significant insight on understanding the microphase separation and the domain structure of urethane and urea hard segments and polyether soft segments in foam.Furthermore, the authors analyze the influence of hydrothermal degradation on the microphase structure of the foams. A detailed comparison of the fundamental results with conventional foam durability tests (e.g., humid aged compression sets) is described, and the hydrothermal degradation mechanism and the influence of catalysts on the foam stability are discussed.

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Section: Solid-state Nmrmentioning

confidence: 99%

“…The formation reaction of polyurethane foams basically consists of two reactions: (1) isocyanate with alcohol to form urethane and (2) isocyanate and water to form urea and carbon dioxide i.e.,…”

mentioning

confidence: 99%

Characterization of Local Structures in Flexible Polyurethane Foams by Solid-state NMR and FTIR Spectroscopy

Oka

Tokunaga

Masuda³

et al. 2006

Journal of Cellular Plastics

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“…Findlay and Harris showed that transient NOE effects in polyester films necessitate the use of long recycle delays in gated decoupler experiments if accurate spectral intensities are desired.16 Root and co-workers observed similar complications in saturation-recovery experiments on block copolymers with a mobile soft segment. 17 McDowell and co-workers established that mobile methyl groups control the relaxation and transient NOE's in crystalline alanine and that relaxation is anisotropic in accordance with the anisotropic motion of the rapidly rotating methyl gr0up.18J9 White and Haw measured steady-state NOEs and growth rates for several crystalline organic solids and suggested that for Bisphenol A, the NOE growth rates were a function of the distance from the rapidly rotating methyl group.20 Douglass and McBrierty, in an earlier wideline study, included transient lH-19F NOE measurements in their evaluation of polymer miscibility in poly(viny1idine fluoride)/poly(methyl methacrylate) blends. 21 In this study, we report the use of steady-state and truncated driven 13C magic-angle spinning (MAS) NOE experiments for probing polymer-polymer miscibility and intermolecular interactions in solid polymer blends at temperatures well below Tr This work was motivated by our continuing effort to characterize solid polymer blends and the desire to extend NOE measurements to true solid polymer blends in a high-resolution magic-angle spinning 0 1993 American Chemical Society mode for the first time.…”

Section: Introductionmentioning

confidence: 99%

Probing miscibility and intermolecular interactions in solid polymer blends using the nuclear Overhauser effect

White¹,

Mirau²

1993

Macromolecules

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We discuss a new strategy for probing polymer-polymer miscibility and detecting specific intermolecular interactions in polymer blends by exploiting nuclear Overhauser effects (NOE) in 13C magicangle spinning (MAS) NMR spectra of solid blends. In the comparison of deuterated polystyrene (PS)/ poly(viny1 methyl ether) (PVME) blends cast from toluene versus chloroform, steady-state equilibrium NOE enhancements of the PS signals were observed for the toluene-cast films but not for the chloroform-cast films. Since cross-relaxation of the PS carbons may occur only through dipolar interactions with PVME protons (which have an inverse sixth power dependence on the internuclear distances), this demonstrates molecular level miscibility for the blends cast from toluene only. Below Tg, methyl group rotation about the C3 axis is the only motion fast enough to stimulate dipolar cross-relaxation in the blend. Additional information concerning the molecular structure of the blend was obtained from the NOE growth rates for each type of carbon nucleus in the blend. The cross-relaxation rate constants for the PS aromatic ring carbons were several times greater than that of the PS main-chain carbons. This implies that the phenyl ring is much closer to the methyl group of PVME than to the main-chain carbons of PS. These results suggest that there exists a specific intermolecular interaction between the PS phenyl ring and the PVME methyl group in the solid state. Such an interaction has previously been suggested for polymer blend solutions. IntroductionPolymer blends, mixtures, and composites are commercially important materials, and the increased interest in these materials is reflected by the variety of methods that have been developed to study polymer-polymer interfaces, to probe polymer miscibility, and to detect specific intermolecular interactions. Magnetic resonance methods have played an important role in evaluating the length scale of polymer mixing and for characterizing the intramolecular interactions. The 'H spin diffusion measured via the T1 and T1, relaxation times are frequently used to establish the length scale over which the blend is homogeneously m i~e d .~J A single averaged value for the lH 2' 1, is observed if the two constituents in a polymer

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“…Those assignments are consistent with published results. 36 The peak observed in the carbonyl region at 154 ppm ( Figure 2) are attributed to the urethane/urea carbonyl (C4) carbon. The aliphatic region is dominated by three carbon peaks at 27, 65 and 71 ppm that arise from the PTMO soft segment.…”

mentioning

confidence: 99%

“…The peaks at 125 and 133 ppm may result from conformational differences in the solid state, as indicated by dipolar dephasing experiments. 36 13 C CP/MAS NMR Spectra of PUU-OPA Figure 3 shows the 13 C CP/MAS spectra of PUU-OPA-x for various OPA contents. The OPA carbons and the aromatic rings of the PU-prepolymer all contribute to the aromatic region.…”

mentioning

confidence: 99%

Morphology of Segmented Polyether Based Poly(urea-urethane) Thermoplastic Elastomers

Liu

Hsu

Wang

2006

Polym J

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ABSTRACT:New aniline-containing segmented poly(urea-urethane) (PUU-OPA) based on polyether polyurethane prepolymer and an oligomer of amine-terminated polyaniline (OPA) were prepared as a conductive material. The amine-terminated functional groups of OPA were introduced into the poly(urea-urethane) (PUU) structure as a chain extender to form the hard segment of the copolymer with urea-linkage. The morphology of PUU-OPA was examined by the transmission electron microscopy (TEM) and solid-state 13 C NMR approaches. The conductivity of the copolymers is found to be ranged from 0.83 S/cm for the neat OPA to 1:96 Â 10 À6 S/cm for the resultant copolymers. TEM measurements clearly reveal the microphase separation. Various contact time CP experiments indicate that T CH and T 1 (H) of the soft segment carbons declined as the OPA content increased. These results indicate that the chain mobility and the domain size of the soft segment in the copolymer on the nanophase scale gradually decreased as the OPA content increased. [doi:10.1295/polymj.PJ2005204] KEY WORDS 13 C NMR / TEM / Poly(urea-urethane) / Morphology / Polyurethane / Polyaniline (PANI), one of the most promising intrinsically conducting polymers, has been attracted considerable attention in recent years because it has a relatively high conductivity and potential application in electronic devices.1,2 Polyaniline is generally prepared by oxidative the polymerization of aniline in acid media using an external oxidant such as ammonium peroxydisulfate, (NH 4 ) 2 S 2 O 8 , and can exist as a number of unique structures, characterized by the oxidation state, which determines the ratio of amine to imine nitrogens, and the extent of protonation. 3 The emeraldine base (EB) is one of the several possible structures. The conducting form of polyaniline can be easily prepared by doping the EB with a protonic acid resulting in a complex acid salt. The members of the polyaniline family are difficult to handle because of their brittleness and poor solubility in polar organic solvents. The processing of emeraldine base is difficult, because EB decomposes below its softening or melting temperature.4-7 Therefore, the processibility of EB has been the subject of several investigations over the last few years. [8][9][10][11] The earlier attempts at processing polyaniline focused on modifying the chain structure by copolymerization or derivation with hydrophilic or alkyl groups. These attempts resulted in a first successful step toward the so-called soluble polymer. Recently, attempts have been made to synthesize aniline oligomers with well-defined structures and amine end-groups and thus improve their solubility and capacity to undergo further polymerization have been reported.12-18 Polyurethanes (PU), comprising a polyether or polyester soft (flexible) segment and a diisocyanate-based hard (rigid) segment, are well known to be tough materials and are typically employed as additives to improve the toughness of brittle materials. The incompatibility between the hard segment and the ...

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Carbon-13 NMR investigation of a poly(urethane-urea) system

Cited by 36 publications

References 4 publications

Characterization of Local Structures in Flexible Polyurethane Foams by Solid-state NMR and FTIR Spectroscopy

Characterization of Local Structures in Flexible Polyurethane Foams by Solid-state NMR and FTIR Spectroscopy

Probing miscibility and intermolecular interactions in solid polymer blends using the nuclear Overhauser effect

Morphology of Segmented Polyether Based Poly(urea-urethane) Thermoplastic Elastomers

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