Impact of clay modifier on structure, thermal, mechanical and transport properties in polyurethane/Maghnite nanocomposites as barrier materials

A thermoplastic polyurethane (TPU) nanocomposite was synthesized based on Maghnite as an inorganic reinforcement phase. The result of this study was to evaluate the gas barrier properties of a thermoplastic polyurethane (TPU) material containing clay nanoparticles. The preparation of the thermoplastic polyurethane prepolymer with NCO terminations was carried out using an in situ solution polymerization method. The clay has already been modified by intercalation of 12-amino decanoic acid molecules NH2(CH2)11COOH (12-Mag). The polyethylene glycol/tolylene matrix 2,4-diisocyanate (PEG/TPI) was widely compatibilized with 12-Maghnite organo-modified clay. The results obtained by XRD, transmission and scanning electron microscopy (TEM and SEM) revealed that 1% (by weight) of the modified Maghnite was well dispersed in the polyurethane matrix. Thermogravimetric (TG) tests showed that nanocomposites could improve thermal stability. The gas permeability was examined by means of a membrane separation device. Significant improvements to the barrier properties were observed. The mechanical properties of the nanocomposites were evaluated according to the filler material used and the TPU matrix.


Introduction
TPU is a thermoplastic elastomer consisting of linear segmented block copolymers composed of rigid and flexible segments, synthesized by two different processes: a one-step polymerization process and a two-step polymerization process [1]. Due to their versatility, polyurethanes have a great diversity in the polymer sector, whether in adhesive, varnish, paint or elastomer. By adjusting the monomer composition, additives and reaction conditions, polyurethanes can be converted into a wide range of extremely soft elastomers with densities of 6 to 1220 kg/m 3 to rigid plastics [2][3][4]. Polyurethanes refer to a group of polymers whose main sequence is composed of aromatic or aligned sections connected to each other by urethane groups. For the synthesis of polyurethanes, substances such as Lewis bases and acids as well as organometallic compounds are generally used [5,6]. Catalyzing the production of polyurethane reduces production time and creates economic savings. It is, therefore, essential from a commercial point of view that the synthesis of polyurethane can be carried out within a limited period. PU is a multifunctional polymer material with many properties including high abrasion resistance, low tear resistance, high shock absorption, flexibility, and elasticity. An organic load significantly increases the performance capacity of polyurethane (PU) [7,8]. The surface treatment process consists of two phenomena: the toxicity effects that can be more controlled (compared with isocyanates), as well as the reactivity of the components, their structure, their characteristics, their processing potential, and the total quality of the materials obtained [9][10][11]. Physical factors, in particular thermal conditions and the duration of annealing, have a strong influence on the morphology of polyurethanes, as per the evidenced by the studies of Cooper et al., who have established a direct and obvious phase separation relationship between the rigid and soft segments of the polyurethanes as a function of temperature [12,13]. Fabrication of materials by in situ polymerization led to the design of crosslinked polyurethane nanocomposites, and the presence of clay channels became more important as the polymerization process progressed [14,15]. Clay particles, with size distribution of 5 nm range, help to improve the properties of polyurethane nanocomposites, including tensile strength, tensile modulus, and stress-at-break [16,17]. The contribution of clays to a variety of environmental contexts and their applications are increasing [18,19]. Clays also have considerable adsorption properties, mainly because of their large specific area [20]. In addition, effluent is treated by aqueous adsorption from clay modified by inorganic or organic molecules [21][22][23]. The aim of this research work is to synthesize and study the structure-property relationships of nanocomposite polymers based on PU and Maghnite as clay reinforcements. In this study, the objective is to exploit the use of a new montmorillonite-type clay as a nano-reinforcement material in a polymer matrix. We selected Algerian clay to disperse to obtain a highly improved ultimate material with physical properties. To this aim, we were interested in: the pre-treatment and surface modification of Maghnite and its use as a nano-reinforcement for the in situ preparation of TPU/12-Maghnite (12-Mag) nanocomposite. In the first part, the interest of Algerian clay as a nano-reinforcement material was highlighted through the study of the properties of simple TPU-Maghnite systems elaborated by in situ process. The load rate of Maghnite modified to a cationic exchange capacity of 1CEC was evaluated to determine the physico-chemical and thermal characteristics of the developed materials. The second part is entirely intended for the synthesis of TPU/12-Mag, obtained by in situ polymerization, in which 12-Mag acts both as a booster and a catalyst. Different compositions were developed to consider the influence of the 12-Mag content on its dispersion quality. Thermal and mechanical properties were analyzed to assess the thermal stability and mechanical strength of the filled systems compared to the unfilled systems. We have also synthesized polyurethane/ clay nanocomposites that are used as a gas barrier property.

Preparation of Maghnite organophile (12-Mag)
The unmodified Maghnite referred to as Na-Mag (Sigma Aldrich, 99%) with a cation exchange capacity equal to 92 meq/100 g was dried at a temperature of 110 °C and under vacuum for at least 2 days. We prepared a modified clay (12-Mag) by cation exchange process, which involved the exchange of the sodium ions Na + present in Maghnite with 12-aminodecanoic acid in aqueous solution according to the procedure described in the literature [24].
Magnetite was organomodified with 12-aminodecanoic acid to make this clay organophilic and use it more effectively.

Synthesis of nanocomposites
The synthesis of polyurethane/Maghnite nanocomposites was carried out by a solution polymerization process with 1:2 ratio of polyethylene glycol (PEG 2000) and tolylene 2,4-diisocyanate (TPI) with 12-Mag as the catalyst. The TPU clay nanocomposites were developed according to the method reported in the literature [25]. A 5 g of polyethylene glycol was introduced into a three-necked reaction vessel and dissolved in dimethylformamide. After swelling of the polyethylene glycol in DMF, a specified amount of 12-Mag (based on monomer weight percentage) and tolylene 2,4-diisocyanate (TDI) (0.018 mol/L) were gradually incorporated into a reaction vessel. The potassium salt of hydroquinone sulphonic acid was dissolved in DMF and added dropwise at 65 ºC. The reaction mixture was heated under a nitrogen atmosphere at a temperature of 90 ºC for 6 h. A film of TPU/12-Mag nanocomposites was obtained by pouring the emulsion onto a Teflon mold. These nanocomposites were dried under vacuum at 70 °C before being weighed to determine the yield of the reaction. Table 1 gives an overview of the content of the samples obtained and sorted according to their 12-Mag content. The codes and composition of the nanocomposites are given in Table 1 ( Scheme 1).

Characterization
FTIR analysis was performed on a Bomem FTLA 2000-ABB (SPECAC Golden Gate: ATR) using an ATR in the 400-4000 cm −1 range. The XRD analyses were performed at room temperature using a Bruker D8 Advance X-ray diffractometer with a monochromatic Cu-Kα 1 radiation source (λ CuKα1 = 0.1542 nm) operating at an accelerating voltage of 40 kV and a current of 35 mA. The dispersion of the clay sheets (12-Maghnite) in polyurethane was examined by transmission electron microscopy (TEM) (Hitachi H800 MT at 200 kV and LEO 922 Omega at 160 kV) under an accelerating voltage of 80 kV. Scanning electron microscopy was used to visualize the micro-dispersion of montmorillonite within the various mixtures. The visualization of the samples was carried out using a Jeol JSM-7001 F microscope. The applied electric field was higher than 109 v/m and the required accelerating voltage was between 0.1 and 30 kV. Measurements by thermogravimetric analysis (TGA) were carried out using a Perkin & Elmer type instrument (TGA4000) in an inert atmosphere (nitrogen) and over a temperature range of 30 to 880 °C with a heating rate of 20 °C/min. A Brookfield DV-I + rotational viscometer was used to perform the rheological evaluations. Measurements were obtained using an 18.66 mm diameter vessel and a 5.88 mm diameter S31 rod. At rotational speeds between 5 and 100 rpm, a correlation was established between the viscosity measurements and the shear rate using the following equations: ω (rad/s) = 2π (speed)/60; S (s −1 ) = 2ωRc 2 / (Rc 2 -Rb 2 ). The conversion factor ω, Rc, and Rb correspond to the angular velocity rate, vessel radius rate, and spindle rate, respectively. All specimens were tested in their  1 3 branched form. The tensile test was carried out to evaluate the tensile properties of different nanocomposite compositions, to determine the influence of the clay addition on the tensile properties of the virgin matrix. Young's modulus, tensile strength, and elongation-at-break were evaluated as a function of clay mass fraction in all series of nanocomposites. Tensile tests were carried out at room temperature on a Universal testing machine (Zwick Roell) assisted by a microcomputer. The specimens were held during the test by pneumatic jaws to prevent slippage of the specimen during the tensile test. The initial strain rate was set at 5 mm/min. Permeability was tested at constant pressure using a membrane separation unit. As shown in Fig. 1, the IR spectrum of 12-Maghnite has features combining bands specific to montmorillonite and 12-aminodecanoic acid. A broad band between 3254 and 3028 cm −1 is associated with the nitrogen stretching band. New bands appear at 2933 and 2858 cm −1 , respectively, attributed to asymmetric/symmetric C = H stretching. A combination of O-H deformation and N-H stretching was observed at 1625 cm −1 [26]. These IR results clearly demonstrate the fictionalization of the clay. Figure 1 shows the intensity and the amount of water adsorbed by the clay samples used in this study. The presence of adsorbed water contributes to the H-O-H bending region (1625 cm −1 ). The intensities of the two strong adsorption bands at 2933 and 2858 cm −1 represent the anti-symmetric and symmetric CH 2 stretching modes of the amine, respectively, and they proportionally increase the stacking density of the ammonium chains in Maghnite galleries [27]. Figure 2 shows the FTIR spectra of 12-Mag, pure TPU, and the different TPU% nanocomposites that were synthesized. The infrared spectrum curve of the nanocomposites is in perfect agreement with that of the pure polyurethane, we detected numerous bands characterizing the PU, namely more exactly a band around 1739 cm −1 , which is due to the stretching of the carbonyl group associated with the urethane grouping HN-COOCH of the ester function. A new band at 1097 cm −1 corresponds to the stretching of C-O-O ester group [28]. There are also distinct bands at 2909 and 2846 cm −1 , respectively, which correspond to the asymmetric and symmetric elongation vibrations of methylene group. The presence of the peak characteristic at 3300 cm −1 was attributed to the NH flexion vibration of the urethane produced during the reactions of NCO and OH groups.

FTIR analysis
The peak observed at about 3626-3623 cm −1 is due to the presence of hydroxyl groups (OH) associated with octahedral aluminum in the constitution of Maghnite. It becomes  significantly more intense when the Maghnite content is high. However, a band at 3336-3340 cm −1 reflects extension of N-H groups from primary amines of aliphatic character. There are also two bands at 1251 and 1531 cm −1 associated with the extension of C-N groups and out-of-plane bending of NH groups, respectively. The stretching of CH chains in the nanocomposites was largely invariant, indicating that the clay grains were not responding during the formation of H-link of -NH groups in the urethane. In addition, we also identified several absorption bands as follows: 660 cm −1 (CH out of the bending plane), 1157 cm −1 (CO stretching), 1390 cm −1 (CH bending), 1458 cm −1 (CH 2 plane shearing), 2954 cm −1 (CH 2 symmetric stretching), respectively, as well as groups appearing around 1050-1300 cm −1 , corresponding to the C-O stretching vibration of the ester group. Data processing by FTIR spectra showed a good sequestration capacity and the strong interaction that exists between the clay and polymer [29].

X-ray diffraction analysis
The XRD patterns of the modified clay and TPU% nanocomposites at various weight strengths are both illustrated in Fig. 3. In this figure, the diffractograms of sodium Maghnite (Na-Mag) and modified Maghnite (12-Mag) are illustrated. The peak is identified at 2θ = 5.6° for Na-Mag, corresponding to a spacing distance of d(001) = 12.9 Å. After the incorporation of alkyl ammonium ions, the peak spacing distance between the silicate layers became d(001) = 19.12 Å. A strong peak was observed at 2θ = 4.21 ± 0.03° (d-spacing of 19.12 ± 0.1 Å) that was coincided with values reported by others [30]. A slight increase in the interfoliar distance is observed, which can be explained by the short alkyl chains of the surfactant and the heterogeneous organization (dispersion) of the Maghnite sheets. The X-ray diffraction patterns of pure PU and PU nanocomposites are shown in Fig. 4. No peaks are noticeable in the PU nanocomposites containing 3% (by weight) clay. This result illustrates the total loss of the organized and the orderly arrangement of the clay layers, with the exfoliation of the clay platelets. The exfoliated clay structure further indicates that the silicate layers are well distributed in the PU matrix. TPU nanocomposites containing 1% and 5% (by weights) of clay show weak and broad peaks at 2θ = 2.44 ± 0.07° (d-spacing of 17.9 ± 0.3 Å), and 2θ = 2.34 ± 0.03° (d-spacing of 19.4 ± 0.2 Å), respectively. In cases where the percentages of modified Maghnite are 1% and 5% (by weights), the spacing of the clay galleries increases compared to 12-Maghnite, revealing that polyurethane chains have penetrated into the structure of Maghnite layers, resulting in an intercalated clay morphology [31]. The intensity peaks present in the nanocomposites have decreased compared to 12-Mag, indicating that parts of the nanocomposites have been partially exfoliated. The presence of the peak located in the montmorillonite zone at 2.44° for TPU1% is an indication that the intercalated phases are adjacent to the montmorillonite in its original state. There has been no reaction between 12-Mag and TPU, and because the mixture is not miscible, the conventional materials were obtained (composites). For a clay load of 7% (by weight) (12-Mag), the basal spacing d(001) is slightly lower than the modified clay spacing, which means that nanocomposites are likely agglomerated. It is assumed that the 12-Maghnite aggregate has lower gallery spacing due to a tighter stack of platelets, which would increase the 2θ value. An inadequate dispersion of the silicate layers in the PU matrix would be the consequence of a high amount of 12-Maghnite present in the structure, so that the free volume is reduced considerably.

Transmission electron microscopy analysis
To confirm the relevance of the X-ray diffraction results, the attached Maghnite (Na-Mag) and its organo-modified counterpart were exposed to a transmission electron microscopy (TEM) study, as illustrated in Fig. S1 (in Supplementary  Materials). The TEM images are obtained on Na-Magshow structural homogeneity in terms of interlayer distance. In contrast, 12-Mag revealed a striped pattern at the nanoscale, revealing an intercalated structure where surfactants were interspersed between Maghnite layers. These results are consistent with those obtained by XRD analysis. In Fig. 5, we display the TEM images of TPU% nanocomposites with the 1%, 3%, 5%, and 7% (by weights) of 12-Mag. The TEM analyses of the synthesized nanocomposites incorporating 3% (by weight) of 12-Mag are illustrated in Fig. 5b. On the images, we can see the different clays marked with rows and lines, each line corresponding to an exfoliated structure. The segments are broken apart, forming an exfoliated structure. In contrast, TPU% nanocomposites containing 1% and 5% (by weights) of 12-Mag are illustrated by ordered lines that reflect an intercalated structure [32]. For an organic clay contents of 1% and 5% of the modified 12-Mag clay (Figs. 5a, c), the lamellar fillers are arranged in a linear intercalated assembly with almost uniform d-spacing. The TEM image profiles of TPU1% and TPU5% nanocomposites favor the constitution of an intercalated morphology according to the order and disposition of the montmorillonite layers. In the case of TPU1%, the presence of intercalated nanoplatelets in the form of small tactoids associated with Maghnite aggregates can be observed. In part 5d for TPU7%, the difference between the polymer matrix and the modified Maghnite agglomerates can be clearly seen during the polymerization process of the monomer outside the montmorillonite cage areas. This result could be attributed to the presence of large proportions of Maghnite, whose active surface was only around clay agglomerates, while the active sites were located in the center of the clay blocks, where Maghnite retained its crystalline structure.

Scanning electron microscopy analysis
The scanning electron microscopy (SEM) images of Na-Mag and organo-modified Maghnite are shown in Fig. S2 (in Supplementary Materials). The SEM images reveal that the morphology of the modified Maghnite is maintained after treatment with 12-aminododecanoic acid. It should be noted that the granulometry of the Maghnite produced varies according to size between 1 and 10 µm. The intercalation process is being established in the interlamellar space. This explains the morphological similarity between sodium Maghnite and organically modified clay (12-Maghnite). In the SEM image of the modified Maghnite presented in Fig. S2 (in Supplementary Materials), the aggregates are largely dominant in Figures 6a-d may illustrate different morphologies of pure TPU and its nanocomposite samples. In the cross-section of pure PU and TPU3% samples (Figs. 6a, b), a smooth and regular morphology is evident, which indicates the homogeneity of their structure. Stress interaction at the ends of the failure lines occurs and restricts cracking propagation of the stresses. The images taken have revealed a homogeneous and uniform dispersion of the Maghnite fillers in the TPU matrix and coarse roughness of the surface films. Once the silicates are well distributed, numerous fissures of the non-linear type take shape and tend to grow to the point of interfering with each other. The high viscosity of the dispersion phase and its cross-linking during the polymerization process generate an irregular interface. Furthermore, the strength of polymeric materials is greatly impacted by fissure development at the molecular level. The more these winding and tortuous cracks are formed, the more energy must be absorbed to break the material [33]. Slight fibrous structures were observed during morphological tests at the time the Maghnite concentration reached 1% (by weight). Pore size measurements showed that the average diameter was 3 ± 2 µm for a 1% (by weight) of 12-Mag nanocomposite and the perimeter was 5 ± 3 µm for a 5% (by weight) of 12-Mag nanocomposite. This study shows that high concentrations of 12-Mag favor the phase breaking performance as a result of the aggregation found in the TPU matrix. At higher magnifications of a 5% by weight of 12-Mag nanocomposite (Fig. 6c), more voids appear within the cavities, demonstrating that intercalation/aggregation exists throughout the TPU matrix. In the case of a 7% (by weight) nanocomposite (Fig. 6), 12-Mag aggregates would saturate the matrix so that the morphology becomes visibly layered and rough.

Thermogravimetric analysis
The thermal stability of TPU-based thermoplastic materials and TPU% nanocomposites was studied by thermogravimetric analysis (TGA), the result of which is shown in Fig. 7. The results show that, compared to pure TPU thermoplastic polyurethane, the thermal stability of nanocomposites was improved after using a significant proportion of 12-Mag. In Fig. 7, the TGA thermogram curve of TPU and TPU% containing different weight percentages of clay nanocomposites  Table 2. In most cases, the presence of 12-Mag affects the thermal stabilities of the realized nanocomposites in two distinct ways: catalytic degradation of the polymer and stability enhancement by oxygen according to the barrier effect principle [34]. The materials synthesized on the basis of TPU% (TPU/12-Mag) exhibit two distinct phases of thermal degradation. The phases of the degradation process are as follows: the first degradation phase is related to the disappearance of the acetate group, which occurs at temperatures of 300-400 °C. The degradation of the acetate main chain leads to a second phase. Above the limit of 211.17 °C, the samples show very low weight losses and undergo decomposition at about 312.78 °C. The degradation temperature of TPU% nanocomposites is slightly higher than that of pure TPU material. The TPU is fully dehydrated and has a relatively good thermal stability. According to Fig. 7, the temperature range of 461.3 ºC to 600 ºC corresponds to a significant mass loss due to dehydroxylation of the OH structural units of the 12-Mag clay. The corresponding peaks are associated with 12-Maghnite dehydroxylation. It should be noted that there is a significant change at lower temperatures of organoclay dehydroxylation. This development is due to the penetration of groups of methyl surfactants in the siloxane layer. After reaching the temperature of 750 °C, a residue of about 28% of the TPU% nanocomposite samples was generated while TPU generates a residue of about 20% at the same temperature. These results highlight that 89% of the initial modified Maghnite added was quantitatively incorporated into the polyurethane matrix as an exfoliated and intercalated structure, and that this may lead to a change in the degradation mechanism of TPU% nanocomposites at high temperature. The best dispersion is obtained for the TPU3% sample compared to the other percentages of organic Maghnite (12-Mag) [35]. Figure 8 shows the viscosity behavior of pure polyurethane (TPU) and TPU nanocomposites at ambient temperature. According to this figure, a reduction in the shear rate as well as in the overall viscosity of the pure polyurethane was observed throughout the procedure. This behavior is simply explained by the fact that Maghnite platelets interfere with the polymerization process, and thus cause the creation of polymer chains of lower molecular weight during the curing process. The reaction of pure polyurethane (TPU) exhibits a shear dilution phenomenon due to the low concentration of PU obtained during polymerization. Consistency of shear thinning behavior was also recorded and observed in the solutions of TPU-1%, TPU-3%, TPU-5%, and TPU-7%. In this context of coating applications, it is interesting to know that the shear thinning behavior promotes good material spread and reduces the possibility of aggregate formation during the processing.    Figure 9 illustrates the comparison of mechanical performance of a neat polymer (TPU) and those of TPU/12-Mag nanocomposites. The test results for tensile strength (TS), elongation-at-break (EB), and Young's modulus (MPa) are shown in Table 3. As shown in Fig. 9, the tensile strength and elongation-at-break increase as the Maghnite content increases up to 5% (by weight). The results obtained by combining TPU and 12-Mag are consistent with the diffusion of thermoplastic polyurethane (TPU) chains in the modified silicate layers and the intense interactions that exist between them. As such, it is reasonable to speculate that the nanocomposites can be moderately loadable compared to pure TPU. The tensile stress increases to 14.3 MPa, representing almost a 78% increase when 3% 12-Mag is added to TPU as compared to an untreated TPU. This is related to the hardening and strengthening of TPU by the insertion of the modified Maghnite uniformly dispersed throughout the TPU matrix. TS and EB are reduced in samples containing 5% (by weight) due to aggregation of Maghnite (12-Mag), resulting in a weak interaction between the Maghnite layers and the TPU matrix [36]. According to Fig. 9, an increase in stiffness, tensile strength, elongation-at-break is observed as a result of the presence of modified Maghnite  in the TPU thermoplastic. During the charging process, it is concluded that these properties will evolve due to a better coordination or association between the filler and the matrix and an optimal dispersion. Impact resistance was improved significantly at a loading rate of 3% (by weight). Figure 10 illustrates an apparent improvement in the Young's modulus of nanocomposites compared to pure TPU. The results obtained showed that the stiffness of the nanocomposites is proportional to the increase of the filler content, for a relatively significant stiffness limit. This is mainly due to the improved ability to adhere to the 12-Mag and the (TPU) matrix ( Fig. 10) [37]. In parallel to the previous results, better results regarding the improvement of the Young's modulus were obtained using a loading rate of 3% (by weight) of modified Maghnite (12-Mag). These results suggest that the presence of Maghnite (12-Mag) is likely to reduce the molecular mobility of polymer chains, resulting in a less flexible material with a high Young's modulus. The results indicate that the nano-reinforcement (12-Mag) has a synergistic effect on the tensile strength, and significantly reduces the flexibility of the polymers. According to Fig. 10, it is observed that the tensile strength and elongation-at-break of the nanocomposites concerning the modified Maghnite are better than those of the attached Maghnite (Na-Mag) at a loading rate of 3% (by weight).

Gas permeability adsorption study
The permeability tests were carried out using the constant pressure membrane separation method. Table 4 contains the oxygen permeability values for the TPU/12-Mag nanocomposites. The TPU membrane was hermetically sealed inside a dual pressure cell. High pressure oxygen (1.5 bar) was kept in one cell while the other cell was maintained at atmospheric pressure. The proportion of gas transported within the membrane is established on the basis of the following equation from the tortuous path model or Nielsen model where P is the gas permeability of nanocomposites, P 0 is the gas permeability of polymer,∅ c is the volume fraction of clay, and A c is the average aspect ratio of clay. For the TPU/12-magnanocomposites film, the oxygen and nitrogen permeability decreases as the clay loading increases, indicating that the organoclay strengthens the oxygen and nitrogen barrier of the TPU. The gas diffusion coefficient is related to the molecular size of the gas, the stiffness and mobility of the polymer chains, and the condensability of oxygen. Oxygen promotes higher solubility in the polymer due to the condensability of O 2 that is 108 K. The oxygen permeability is reduced by 62% by adding 5% (by weight) of clay. The barrier properties decrease when the clay loading is higher than 3% (by weight). From the dimensions of the clay platelets, the relative permeability can be calculated for different numbers of clay stacks (N). The aspect ratio of the clay platelets is assumed to be 218 nm, which is a typical MMT value. The permeation rates in oxygen and nitrogen gas are given in Fig. 11. The steady-state distribution of solutes across the loads of multilayer membranes with monodisperse loads aligned in a regular array is calculated according to the equation below [38,39]. (1) According to the Nelson's tortuous model (Eq. 1), the number of TPU nanocomposite stacks is around 2, as shown in Fig. 12. The main assumption made during the development of Eq. 2 is that the clay platelets are monodisperse and aligned in a regular pattern.

Conclusion
In this study, a clay type from Algeria (Maghnite) with a high catalytic capacity was selected as filler for the purpose of synthesizing polyurethane matrix-based nanocomposites. The FTIR results confirmed a good interaction between 12-Maghnite and the polymer. XRD, TEM, and SEM analyses revealed that the structure of the obtained nanocomposites exhibits an exfoliated and intercalated structure that results in a homogeneous dispersion and uniform distribution of the nano-reinforcement in the polymer chains.  The gravimetric results showed a significant improvement in thermal stability, reaching a significant increase in temperature. The mechanical measurements also showed that tensile strength, Young's module, and elongation-at-fracture increased with the modified Maghnite content (12-Mag).
The permeability factor to oxygen and nitrogen of the TPU was reduced after the integration of 12-Mag. The barrier properties were improved in the presence of Maghnite (12-Mag), perfectly dispersed in the thermoplastic polyurethane chain, increasing the oxygen permeability by 62%. The interactions observed between the modified Maghnite and the polyurethane matrix established that the composite material is likely to improve oxygen and nitrogen permeability. The study of nitrogen and oxygen adsorption showed a remarkable improvement in the specific surface area of the composites compared to pure PU, due to the effect of Maghnite, which is present in the form of layers.

Supplementary Information
The online version contains supplementary material available at https:// doi. org/ 10. 1007/ s13726-023-01167-8. ment of Chemistry, Faculty of Exact and Applied Sciences, University Oran1, the site Culture and Innovation Project of the graduate students of Polymer Chemistry Laboratory, Department of Chemistry, Faculty of Exact and Applied Sciences, University Oran1 is also recognized.
Funding Sources of funding are listed in the acknowledgements.

Data Availability
The data sets that were developed and/or evaluated in this study are available from the lead author upon request. The data from this study are included as S1 data and S2 data in this published article. The authors are in no way responsible for the invention or alteration of any data or images which may have been used in this work. All coauthors, as well as the directors of the institute where the work was carried out, have expressly, tacitly or explicitly agreed to submit the work. A link and/or reference to the publisher's version of the work on all digital copies for use within its institution. No reproduction or permission to reproduce an adaptation of the work that is substantially identical to the work has been granted for the purpose of commercial publication. Digital copies of the work as published by the publisher are not systematically networked to external users. Use of the work in a manner that implies approval by the publisher, journal or editors of any product or process described in the work.