Hydrogen bonding in dicyclohexylmethane – or diphenylmethane based urea compounds and their polymer counterparts investigated by NMR spectroscopy: Interplay of electronic and geometrical factors

Мокеев, М. В.; Ostanin, Stepan A.; Zuev, Vjacheslav V.

doi:10.1016/j.cplett.2019.137047

Cited by 7 publications

(5 citation statements)

References 15 publications

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“…A complex structure of the soft polymer matrix (the presence of rigid and mobile amorphous phases) is supported by both NMR and dielectric spectroscopy. The local character of double relaxations (β and γ) indicates that rigid and mobile amorphous phases are related to H-bonded and free groups of soft segments [53,54].…”

Section: Discussionmentioning

confidence: 99%

Interplay of Structural Factors in Formation of Microphase-Separated or Microphase-Mixed Structures of Polyurethanes Revealed by Solid-State NMR and Dielectric Spectroscopy

Ostanin

Мокеев

Pikhurov³

et al. 2021

Polymers

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A set of aromatic-oxyaliphatic polyurethanes (PUs) with different mass fractions of components also containing fluorinated fragments was synthesized and studied using various solid-state NMR techniques and dielectric spectroscopy. In contrast to the common model suggested by Cooper and Tobolsky in 1966, the rigid domains of microphase separated PUs are formed, not only by units containing urethane bonds, but also by oxyethylene fragments that form a common rigid phase. The urethane bonds and oxyethylene fragments are incorporated into both rigid and soft phases. Good agreement with the Cooper and Tobolsky model is observed only when solubility parameters are significantly different for the hard and soft segments, such as hydrocarbon aromatics and perfluoroaliphatic blocks.

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Section: Discussionmentioning

confidence: 99%

Interplay of Structural Factors in Formation of Microphase-Separated or Microphase-Mixed Structures of Polyurethanes Revealed by Solid-State NMR and Dielectric Spectroscopy

Ostanin

Мокеев

Pikhurov³

et al. 2021

Polymers

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“…Therefore, the degree of phase separation (DPS) in the PU matrix grows, although not as significantly. Typically, the increase in DPS leads to an improvement in the mechanical performance [37]. The increase in DPS can be connected with the surface of the birch particle, which is covered by hydroxyl functionalities from cellulose and lignin macromolecules.…”

Section: Resultsmentioning

confidence: 99%

High-Performance Castor Oil-Based Polyurethane Composites Reinforced by Birch Wood Fibers

2023

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A new method for the preparation of coatings based on renewable biomaterials such as castor oil and birch flour is suggested in this study. The introduction of birch flour in a polyurethane matrix synthesized from castor oil and oligomeric methylene diphenyl diisocyanate (MDI) leads to a more than doubled value of tensile strength and almost doubled strength of adhesion to steel at 20 wt.% loading. The composite with such level loading has tensile strength equal to 7.1 MPa at an elongation at break of 31%, with an adhesion to steel of 3.71 MPa. Hence, the use of such level loading allows for an increase in tensile strength of 887.5% in comparison with that of polyurethane based on neat (as received) castor oil, leading to a decrease in the value of elongation at break. The adhesion to steel of these composites increases by 185.5% in comparison with starting polyurethane. FTIR and SEM studies identified the mechanism of the reinforcement effect of birch fibers. This reinforcement is based on the good wetting of birch fibers by polyurethane with the formation of chemical bonds between them, and the cellulose and lignin components of wood fillers. As a result, we obtained cheap bio-based coatings with acceptable mechanical and adhesion properties.

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“…A recent report showed that the intermolecular hydrogen bonds are weaker in phenyl-based urea than in their cyclohexane-based counterparts, as determined by variable-temperature 1 H NMR spectroscopy studies. 49 Characteristics of the Films. Optically transparent, colorless, and flexible freestanding films of 3a−f were obtained by casting the polymerization solutions in THF on Teflon sheets (Figure 2).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…This suggests that 3e forms stronger hydrogen bonds than the other nonphenylureas. A recent report showed that the intermolecular hydrogen bonds are weaker in phenyl-based urea polymers than in their cyclohexane-based counterparts, as determined by variable-temperature 1 H NMR spectroscopy studies …”

Section: Resultsmentioning

confidence: 99%

Synthesis of Low-Dielectric Polyureas by Incorporating Phenyl-Substituted Cage Silsesquioxanes in the Main Chain

Kamitani

Nakamura

Watase

et al. 2023

ACS Appl. Polym. Mater.

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Establishing a design concept for low-dielectric constant (ε r ) and low dissipation factor (tan δ) polymeric materials is vital to improve signal transmission rates. Polyurea-based polymers with strong dipole moments have been reported to achieve higher ε r (above 5.0) than most of the traditional polymer dielectrics. However, polyurea-based polymers with low ε r and tan δ values have not been reported yet. In this study, bis(3-aminopropyl)-doubledecker-shaped phenyl-substituted silsesquioxane (DDSQ) (1) was polymerized with various diisocyanates, i.e., methylenediphenyl 4,4′-diisocyanate (2a), 4,4′diisocyanato-3,3′-dimethylbiphenyl diisocyanate (2b), m-xylene diisocyanate (2c), 1,3-bis(isocyanatomethyl)cyclohexane (2d), 4,4′-methylenebis-(cyclohexyl isocyanate) (2e), and hexamethylene diisocyanate (2f), to obtain the corresponding polyureas (3a−f). Optically transparent, colorless, and flexible freestanding films were obtained by casting the polyurea solutions in tetrahydrofuran. Among the tested polymers, polyureas from 2a and 2e exhibited ε r less than 3.0. Incorporation of the DDSQ units produced free volume, resulting in low ε r . Polyureas from 2e and 2f exhibited the lowest tan δ of approx. 7 × 10 −3 . The polyurea from 2e had the lowest urea content and thus had the lowest density and lowest ε r . Additionally, strong hydrogen bonding in the polyurea from 2e inhibited local motion, resulting in a low tan δ even though the urea content was low. Water vapor permeability measurements revealed greater free volume content introduced by the co-oligomerization of polyhedral oligomeric silsesquioxanes (POSS), especially in the polyurea from 2e. Among the reported combinations, the combination of DDSQ and urea groups provides unique low ε r and low tan δ polymeric materials.

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Hydrogen bonding in dicyclohexylmethane – or diphenylmethane based urea compounds and their polymer counterparts investigated by NMR spectroscopy: Interplay of electronic and geometrical factors

Cited by 7 publications

References 15 publications

Interplay of Structural Factors in Formation of Microphase-Separated or Microphase-Mixed Structures of Polyurethanes Revealed by Solid-State NMR and Dielectric Spectroscopy

Interplay of Structural Factors in Formation of Microphase-Separated or Microphase-Mixed Structures of Polyurethanes Revealed by Solid-State NMR and Dielectric Spectroscopy

High-Performance Castor Oil-Based Polyurethane Composites Reinforced by Birch Wood Fibers

Synthesis of Low-Dielectric Polyureas by Incorporating Phenyl-Substituted Cage Silsesquioxanes in the Main Chain

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