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DMTA traces of the supramolecular polymer nanocomposites with 4 wt% functionalized silica nanoparticles and various contents of UPy in supramolecular polymers foamed under 9 MPa, 90 ∘ C for 5 h: (a) elastic modulus and (b) tan í µí»¿.
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In this study, we report fabrication of supramolecular polymer nanocomposite foams with uniform cell structure, high cell density, and expansion ratio using a soft matrix of poly (MA-co-HEMA) and silica nanoparticle fillers, both functionalized with Ureido- Pyrimidinone (UPy) supramolecular groups. Microcellular structures were formed using a batch...
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... seems that increasing the UPy units can form stronger interactions between the supramolecular polymer chains and the UPy-functionalized nanoparticles and make the higher density of physical networks lead to a decreased motion of the chain and consequently increase T g . 39 Figure 7(a) reveals the temperature dependence of the elastic modulus. The increase in elastic modulus is considerably higher for the nanocomposite foams prepared using the matrix with the highest side-chain UPy content (F-U5/SiO 2 (4%)-U). ...
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... dependence of the elastic modulus. The increase in elastic modulus is considerably higher for the nanocomposite foams prepared using the matrix with the highest side-chain UPy content (F-U5/SiO 2 (4%)-U). At 50 ∘ C, as can be seen in Tables 1 and 2, the elastic modulus of the foamed samples is lower than that of the unfoamed samples. In Fig. 7(b), the tan í µí»¿ curves show a complicated behavior. On increasing the side-chain UPy content, the first peak increases and the second peak shows complicated behavior. The increase in the first peak can be related to the higher density of UPy units that form the physical network, but the complicated behavior of the second peak is ...
Citations
... The preparation and structural characterization of UPy units were described by Feldman et al. [52]. 1 H NMR peaks at 2.1, 5.8, and 7.5 ppm corresponded to hydrogen-bonded protons in the UPy moiety. In the FTIR spectroscopy, peaks at 1700, 1667, 1584, and 1524 cm − 1 were related to UPy [53]. The organic-inorganic nanoparticles were functionalized by reacting UPy units with the hydroxyl groups on chains or SiO 2 , using dibutyltin dilaurate as a catalyst in DMF solvent (see Scheme 1) [53]. ...
... In the FTIR spectroscopy, peaks at 1700, 1667, 1584, and 1524 cm − 1 were related to UPy [53]. The organic-inorganic nanoparticles were functionalized by reacting UPy units with the hydroxyl groups on chains or SiO 2 , using dibutyltin dilaurate as a catalyst in DMF solvent (see Scheme 1) [53]. SiO 2 -P (MMA-co-HEMA) (0.07 mol, 7 g) was dissolved in 51 ml dry DMF, and then UPy (0.002 mol, 0.61 g) and DBTDL (3 drops) were added. ...
Novel gel polymer electrolytes (GPEs) based on blends of poly (vinylidene-fluoride) (PVDF) with synthesized organic-inorganic hybrid nanoparticles were prepared by phase inversion process. The hybrid nanoparticles, SiO2-poly (methyl-methacrylate) (SiO2-PMMA) and SiO2-poly (methyl methacrylate-co-hydroxyl ethyl methacrylate) (SiO2–P (MMA-co-HEMA) were synthesized by free radical polymerization. Then, SiO2–P (MMA-co-HEMA) was functionalized by reacting UPy units including the multiple functional groups with hydroxyl groups on chains and SiO2 to form the physical network of SiO2–P (MMA-co-UPy). The chemical structure, crystallinity, porosity, electrolyte uptake, and mechanical and electrochemical properties of the prepared membrane were investigated. The results exhibited that the nanocomposites had more amorphous regions, high porosity, and large electrolyte uptake. Furthermore, SiO2–P (MMA-co-UPy) doped PVDF (GPE-S3) due to synergistic effects of the hybrid nanoparticles and the unique physical network with some functional groups showed the best performance. The GPE-S3 displayed the maximum ionic conductivity of 3.10 × 10⁻³ Scm⁻¹ with electrochemical stability up to 4.8 V (vs. Li⁺/Li) and excellent interfacial compatibility with electrodes. The LiMn2O4/Li cells based on GPE-S3 had also a remarkable rate and cyclic performance. Moreover, it had a favorable modulus (54.6 MPa) at room temperature.
... It determines color loss, macroscopic fragmentation, and progressive reduction of molecular weight; hence, bettering understanding of the involved mechanisms and developing new methods to slow down this type of degradation are extremely active fields [4][5][6]. Modern additives for polymers are capable of absorbing the UV radiation or blocking the free radicals and peroxides produced during the degradation process [7,8]. These substances are generally produced from non-renewable sources, and bio-based materials should not rely on them to improve their performances [9][10][11]. ...
... The water contained in the tannin powder is not readily available and this reduces the reaction kinetics, thus promoting the development of the blowing agent when the viscosity of the polymer is higher and reducing the gas escape towards the outside. Furthermore, CT particles act as cell nucleation sites and enhance the formation of supramolecular structures contributing to the increase of the expansion ratio and cell density [7]. These effects are not significant at low CT content, and pristine PU, TaPU-10, and TaPU-20 foams have similar density. ...
A vegetable tannin, a flavonoid-type natural polyphenolic compound, was used to promote the stabilization of polyurethane foams against UV radiation. Several polyurethane foams were synthesized by using an isocyanate, and a mixture of ethoxylated cocoalkyl amine and vegetable tannin. The content of vegetable tannin was varied from 0 to 40 wt %. The effects of tannin and water (used as a blowing agent) on the foaming kinetics and cellular morphology of foams were investigated. Samples were subjected to accelerated weathering under UV radiation for 3 to 24 h, and FTIR and DMA analyses were conducted to assess the performance change. The former analysis revealed a strong inhibiting effect of tannin on urethane linkage degradation during the UV treatment. The mechanical properties were significantly affected by the addition of tannin. The capability of the foams to withstand UV radiation was dependent on the amount of tannin. At tannin contents higher than 20%, the decrease in mechanical properties under UV irradiation was almost avoided.
The dynamic mechanical properties of supramolecular associative polymer networks depend on the average number of entanglements along the network‐forming chains, Ne, and on their content of associative groups, f. In addition, there may be further influence by aggregation of the associative groups into clusters, which, in turn, is influenced by the chemical structure of these groups, and again by Ne and f of the polymer. Therefore, the effects of these parameters are interdependent. To conceptually understand this interdependency, we study model networks in which (a) Ne, (b) f, and (c) the chemical structure of the associative groups are varied systematically. Each network is probed by rheology. The clustering of the associative groups is assessed by analyzing the rheological data at the end range of frequency covered and by comparison of the number of supramolecular network junctions with the maximum possible number of binary transient bonds. We find that if the total number of the network junctions, which can be formed either by interchain entanglement or by interchain transient associations, is greater than a threshold of 13, then the likelihood of cluster formation is high and the dynamics of supramolecular associative polymer networks is mainly controlled by this phenomenon. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019
A facile way has been investigated to fabricate the phenolic-based carbon foam (PCF) modified with the unique three-dimensional structure of graphene oxide/SiO2 (GO/SiO2) hybrid nanomaterials which were obtained via in-situ preparation method. Results showed that the carbon foam sample modified by 1.5 wt% GO/SiO2 hybrid nanomaterial with a particle size of 80 nm had an electromagnetic interference shielding effectiveness (EMI SE) up to ∼50 dB in X-band only at a thickness of 10 mm. This phenomenon may be ascribed to stable porous structure and nanoparticles assisting in attenuating the electromagnetic wave transmittance. The result enables their application in lightweight electromagnetic protection devices.
