Preparation of flexible highly conductive polyurethane elastomers with low PEDOT:PSS content based on novel feasible pore collapse strategy for flexible conductor

doi:10.21203/rs.3.rs-3908908/v1

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Preparation of flexible highly conductive polyurethane elastomers with low PEDOT:PSS content based on novel feasible pore collapse strategy for flexible conductor

https://doi.org/10.21203/rs.3.rs-3908908/v1

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Meeting the requirements of flexible electronic devices remains a challenge in achieving stable and highly conductive polyurethane composites (CPCs) with minimal loading PEDOT:PSS. In this study, PEDOT:PSS based CPCs were prepared using a novel method involving pore collapse of aerogels. Initially, polyurethane aerogels (PUAs) were synthesized with varying pore sizes ranging from 3.2µm to 9.1µm based on specific formula ratios. Subsequently, solvent evaporation at 120°C caused shrinkage and collapse of the PUAs' pore structure, resulting in the formation of a continuous conductive circuit composed of PEDOT:PSS in polyurethane elastomers (CAPPs). CAPPs containing 1.53 wt% PEDOT:PSS exhibited remarkably high conductivity characteristics (1590 S/m). These CAPPs demonstrated excellent mechanical flexibility as they could withstand stretching, bending, and twisting without significant changes in resistance or affecting LED brightness. Moreover, they proved suitable for use as soft electrodes for electrocardiography (ECG) during exercise to monitor heart rate. This work presents an innovative approach for constructing highly conductive networks through pore collapse of aerogels and obtaining low-loading conductive polymers.

PEDOT:PSS

Conductive polyurethane composites

Aerogel pore collapse

ECG monitoring

In recent years, with the development of flexible electronic devices (e.g., wearable sensors[1–3], electronic skin[4], flexible medical devices[5–7], etc.), conductive polyurethane composites (CPCs) have received a great attention. They are mostly composed of polymer matrix and conductive fillers[8]. The polymer matrix ensures the flexibility and tensile properties of the CPCs, while the conductive filler achieves electrical conductivity by forming a continuous conductive network in the matrix. At present, most of CPCs are prepared via blending or surface deposition[9–16]. Blending (including solution blending and melt blending) is a commonly used method for CPCs. Tzounis et al.[14] prepared thermoplastic polyurethane/carbon nanotubes (TPU/MWCNTs) nanocomposites with MWCNTs (1.0, 2.5 and 5.0 wt%). Among them, the TPU/MWCNT composite containing 5.0 wt% showed higher electrical conductivity (133.1 S/m). Li et al.[15] prepared CNT/polypropylene (PP)/polycarbonate (PC) conductive composites by mixing PP/PC (1:1) with CNT using physical blending and hot pressing. When CNT content was 3 wt%, the CNT/PP/PC composite films had the best conductivity (5.53 S/m). The formation of conductive network is closely related to the dispersion and distribution of conductive fillers in the polymer matrix. Since the conductive filler is easy to aggregate or accumulate at high temperature or in solution, the packing aggregate leads to uneven dispersion and insufficient conductivity. It is difficult to achieve sufficient dispersion of conductive filler by either strong ultrasonic or mechanical stirring treatment[17]. Therefore, to obtain high conductivity, higher filler additives are required, but the flexibility of the polymer matrix is difficult to maintain at higher loads. Another approach to achieve high conductivity with low filler is surface deposition. Chen et al.[12] prepared 3D interconnected carbon nanotube/graphene-based multifunctional epoxy (EP) composites by depositing rGO and CNT onto PU sponge skeletons by layer-by-layer assembly. This hybrid rGO/CNT network provides a certain electrical conductivity (0.01 S/cm) for EP. Chen et al.[16] prepared a 3D porous PDMS (p-PDMS) skeleton by replicating the structure of nickel foam, and then assembled the CNT/graphene hybrid material on the p-PDMS scaffold. The p-PDMS/CNT/graphene (pPCG) conductivity was 27 S/m, while the loading of CNT/graphene was only 2 wt%. However, the interaction between the conductive filler deposited on the polymer surface and the matrix is weak. As a result, the conductive filler is easy to peel off, resulting in poor resistance to mechanical deformation. Surface deposition still cannot solve the problem of achieving good flexibility without losing conductivity and establishing a continuous conductive network in the polymer matrix. In summary, the establishment of a continuous conductive network in the matrix of CPCs is a crucial condition to ensure the uniform conductivity of composites. Therefore, it is still a challenge to study the conductive composite structure design of CPCs to construct a continuous conductive network using low loading conductive filler to achieve flexible deformation while maintaining stable high conductivity.

Among current conductive polymers, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is the most promising candidate for commercial applications due to its good mechanical flexibility/tensile properties, solution processability, excellent conductivity controllability and biocompatibility, high chemical and thermal stability[13, 18–20]. PEDOT:PSS is widely used in different areas of flexible electronic devices such as human health detection[21], electronic skin[22], light-emitting diodes[23], flexible displays[24], and sensors[25]. PEDOT:PSS consists of a conductive PEDOT (positively charged ionic polymer) and an insulating PSS (negatively charged ionic copolymer)[18]. Polycationic PEDOT with a conjugated framework has low solubility in organic solvents or water, and can be tightly bound to polyanionic PSS as a counterion through electrostatic interactions to form highly stable water dispersion[26–29]. PEDOT:PSS can be blended with insulating elastomers or polymers such as poly(dimethylsiloxane) (PDMS)[30], polyurethane (PU)[31], poly(vinyl alcohol) (PVA)[13, 19, 32], and PVP[33] to fabricate flexible stretchable conductors. Yin et al.[32] prepared a highly conductive reduced RGO/PEDOT:PSS/PVA composite fiber film by electrostatic spinning, resulting in an electrical conductivity of 1.7 S/m. Sau et al.[13] prepared stretchable conductive polymer films by blending the soft PVA and the conductive polymer PEDOT:PSS in the presence of different concentrations of the polar organic solvents dimethyl sulfoxide (DMSO) and diethylene glycol (DEG). The optimal conductivities of 32.7×10^− 3 S/cm and 92.6×10^− 3 S/cm were obtained in PVA/PEDOT:PSS films doped with 7 wt% DMSO and 3 wt% DEG, respectively. Mixing these elastomers or polymers with PEDOT:PSS results in conductive polymers that enhance their ductility and flexibility. However, PEDOT:PSS composites are usually prepared by blending or surface deposition, which makes the conductive network unstable and difficult to form a continuous state when the content of PEDOT:PSS is low in the polymer matrix. Therefore, it is necessary to prepare a conductive CPCs through composite structure design, which can not only provide stable and high conductivity at low content of PEDOT:PSS, but also achieve flexible characteristics.

In this study, a series of stretchable polyurethane aerogels (PUAs) were synthesized using the sol-gel method, and PEDOT:PSS was incorporated into the aerogel through capillary action. During solvent evaporation at a specific temperature, the internal pore strength of PUA is insufficient to maintain its original structure, resulting in collapse of the aerogel pores and formation of an embedded polyurethane elastomer with a dense continuous structure of PEDOT:PSS. The relationship between surface morphology, conductivity, and mechanical properties of highly conductive polyurethane elastomers (CAPPs) was characterized. CAPP serves as a conductor connected to luminous LEDs that can withstand stretching/bending/twisting without affecting LED brightness. Additionally, CAPP is utilized as a soft electrode for monitoring ECG signals and changes in human heart rate. These applications demonstrate the feasibility of utilizing pore collapse in aerogels to form a low-loading PEDOT:PSS conductive continuous structure.

2.1 Materials

1,3,5-tris(6-isocyanatohexyl)-1,3,5-triazinane-2,4,6-trione (HDI-trimer) and isophorone diisocyanate trimer (IPDI-trimer) were purchased from Wanhua Chemical Group Co., Ltd (China). Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS, 1.1wt%) aqueous solution was provided by Shanghai Organic Optoelectronic Materials Co., Ltd (China). Tetraethylene glycol (TTEG, AR) was purchased from Shanghai Shaoyuan Reagent Co., Ltd (China). Anhydrous ethanol (EtOH, AR), acetonitrile (ACN, AR), triethylene glycol (TEG, AR), poly(ethylene glycol) (PEG-300) and dibutyltin dilaurate (DBTDL, AR) were purchased from Tianjin Jiangtian Chemical Technology Co., Ltd (China). Moreover, all reagents were of analytical grade and were not further purified.

2.2 Preparation of PUAs

The synthetic route of PUAs is shown in Fig. 1. The synthetic process is as follows: the total molar amount of NCO group of HDI-trimer and IPDI-trimer and the total molar amount of hydroxyl group in TEG, TTGE and PEG-300 is 1:1 (NCO:OH = 1:1), wherein the NCO molar ratio of HDI-trimer and IPDI-trimer is fixed at 5:1. According to the molar ratio of TEG, TTGE and PEG respectively 8:4:0, 8:3:1, 8:2:2, 8:1:3 and 8:0:4, five kinds of hydroxyl mixtures are obtained, which are named A1, A2, A3, A4 and A5. HDI-trimer and IPDI-trimer are added to a 150 mL flask with ACN as the solvent, and dissolved at 25°C, then the one kind of hydroxyl mixture is added, and 0.5wt% DBTDL catalyst is added after stirring evenly. The stirring is stopped after 30 min to form an opalescent sol. The sol is poured into a mold, sealed at room temperature for 12 h to complete the cross-linking reaction, and a wet gel containing ACN solvent is obtained. The wet gel is soaked in EtOH for 5 h to replace the ACN in the gel, and dried at 100°C for 4 h until the mass is mainly volatile, and the final polyurethane aerogel is obtained. According to different mixed alcohols, they are named PUA1, PUA2, PUA3, PUA4 and PUA5.

2.3 Fabrication process of CAPPs

The schematic fabrication process of CAPP is shown schematically in Fig. 2. The preparation process of CAPPs: Firstly, 5 wt% ethylene glycol (EG) and 5 wt% dimethyl sulfoxide (DMSO) were added into the PEDOT:PSS (1.1wt%) aqueous solution, and then the solution was treated with ultrasonic for 30 min until evenly dispersed, and the PEDOT:PSS solution was obtained. The rectangular samples of PUA1, PUA2, PUA3 and PUA4 were cut into 60×2.5×1.5 mm and put into the PEDOT:PSS solution. The sample was vacuumed for 5 h at 25°C, so that the PEDOT:PSS solution entered the aerogel through vacuum effect. The aerogel was taken out and dried at 120°C for 4 h until constant weight. The polyurethane elastomers obtained from PUA1, PUA2, PUA3 and PUA4 according to the above preparation process were named CAPP1, CAPP2, CAPP3 and CAPP4 respectively.

2.4 Characterization

Morphology and chemical element distribution of PUAs and CAPPs were characterized by field emission scanning electron microscopy (FESEM, FEI-Apreo, USA). PUAs and CAPPs samples were treated by vacuum plasma coating and observed in FESEM at 20KV, with a magnification of 500–2000. The chemical groups of PUAs and CAPPs were characterized by Fourier transform infrared spectroscopy (FTIR, Bruker TENSOR 27, Germany), with wave number set at 400–4000 cm^− 1, resolution set at 4cm^− 1, and scanning for 32 times. The mechanical properties of PUAs and CAPPs were characterized by universal tensile testing machine (CMT-4254, Shenzhen, China). The stress and strain of the samples were tested at a tensile rate of 100mm/min and a temperature of 25°C, with each sample repeated 5 times. The elemental composition (C, N, O, S) of CAPPs were characterized by X-ray photoelectron spectroscopy (XPS, Thermo Scientific K-Alpha, USA). The detector was equipped with an Al Kα source (1486.6 eV), with a constant X-ray retention time of 100 ms, a scanning step size of 1.0 eV, and a scanning range of 1200-0 eV. The relative resistance of CAPPs at a fixed 10% strain was measured by an integrated digital source strain gauge (Keithley 2400, Tektronix, USA), and the stability of the relative resistance was investigated by cyclic tensile test. CPPA2 was cut into 8×8 mm size and connected to the sensor pad of an electrocardiograph (Philips M3046A, Netherlands) as a soft electrode. The electrocardiogram was used to monitor the changes of ECG signals in three parts of the human body (upper right, upper left and lower left of the chest and abdomen) in adults at running and resting states.

3.1 Characterization of PUAs and CAPPs

Morphology of PUAs aerogels is shown in Fig. 3. The cross-section of PUA1, PUA2, PUA3 and PUA4 samples shows that the aerogels present spherical interconnection, and is connected by openings pores. The cross-section of PUA5 shows the smooth surface which has less and smaller spherical interconnection, and the aerogel does not exist. The molar ratios of TEG, TTEG and PEG-300 in A1 to A5 of the PUAs synthetic formula are 8:4:0, 8:3:1, 8:2:2, 8:1:3 and 8:0:4, and the molecular weight of TTEG is 194, and the molecular weight of PEG-300 is 300. Because the NCO:OH ratio of the PUAs series samples remains unchanged at 1:1, the distance between the cross-linking points gradually increases from PUA1 to PUA4, and the cross-linking density gradually decreases. For PUA1 with high cross-linking density, the process of solvent evaporation and contraction is relatively weak, and the apparent performance is that the aerogel tends to be in the state of minimum interfacial tension, forming a loose structure with large diameter spherical connections. With the decrease of cross-linking density, the solvent is easier to evaporate from the matrix, and the apparent performance is that the aerogel presents smaller spherical interconnection. For PUA5, the cross-linking density is the lowest among the PUAs, so that it shows the smooth surface and does not have aerogel state after the solvent evaporation (Fig. 3e). Therefore, the preparation of PUAs aerogels needs to maintain a certain proportion of TTEG in order to obtain a certain cross-linking density. The size of the spherical interconnections in the aerogel gradually decreases as PUA1 > PUA2 > PUA3 > PUA4. The pore sizes of PUAs in the FESEM image in Fig. 3 were statistically analyzed by using image software (Nano Measurer 1.2.5). The average pore sizes of PUA1, PUA2, PUA3 and PUA4 were 9.10, 6.65, 5.54 and 3.20µm (Fig. S1), respectively. Morphology of the CAPPs elastomer was shown in Fig. 3a₁-d₁, which was obtained after the PEDOT:PSS solution was infiltrated into the PUAs and dried in a vacuum at 120°C. The pores of the PUAs were significantly reduced to form a kind of elastomers called CAPPs. The results showed that the pore sizes of CAPP1, CAPP2, CAPP3 and CAPP4 were 8.20µm, 5.84µm, 2.36µm and 0.68µm (Fig. S1), respectively, which were reduced by 10%, 12%, 57% and 79%, respectively. According to Table. S1, the mass content of PEDOT:PSS in the CAPPs was between 1.37% and 1.53%, so it could not have a great effect on the pore size. Therefore, the significant reduction in pores was mainly caused by the collapse of pores, where the smaller the cross-linking density of PUAs, the greater the reduction in pores of CAPPs. In the EDS mapping, it was observed that C, N, O and S were uniformly distributed and the mass distribution was 65.9%, 17.7%, 15.6% and 0.8%, respectively, demonstrating the uniform distribution of PEDOT:PSS in the CAPPs (Fig. 3f).

The characteristic functional groups of PEDOT:PSS, PUA4 and CAPP4 were characterized by FTIR spectra. As shown in Fig. 4a, the infrared spectral absorption peak of PEDOT:PSS at 1140 cm^− 1 is related to the asymmetric and symmetric vibration of S-O in the sulfonate group (SO₃H and − SO₃−) of the PSS chain. The peak at 1085 cm^− 1 corresponds to the S-C phenyl bond in the sulfonate. The vibration of the C-S bond of the thiophene ring appears at 945 cm^− 1. It is shown that the absorption peaks of PUA4 at 3365 cm^− 1, 2930 and 2580 cm^− 1, 1697 cm^− 1 and 1125 cm^− 1 are attributed to the N-H bond, CH₂ group, the carbonyl stretching and ether bond of polyurethane, respectively. The spectrum of CAPP4 has almost all the absorption peaks of PUA4 and PEDOT:PSS, and it is found that the positions of the N-H bond and the carbonyl of polyurethane in the spectrum are shifted (from 3365 to 3360 cm^− 1,from 1691 cm^− 1 to 1697 cm^− 1, respectively) due to the hydrogen bond interaction between the amine functional group of CAPP4 and PEDOT:PSS[34], which makes PEDOT:PSS uniformly adsorbed on the CAPP4 elastomer. XPS spectra of CAPP4 in Fig. 4b show the characteristic peaks of C1s, N1s, O1s and S2p. In Fig. 4c, S2p spectra show the presence of sulfur in PSS (peaks at 167.4 and 168.6 eV) and the presence of heterocyclic thiophene in PEDOT (peaks at 163.3 and 164.5 eV)[35]. The results show that PEDOT:PSS is successfully adsorbed on CPPA4 due to the hydrogen bonding.

3.2 Mechanical properties of CAPPs

The stress-strain curves of PUAs are shown in Fig. 5a. The stress of PUAs shows a linear increase with the increase of strain, wherein the tensile strength gradually increases from 10^− 4 to 3.5×10^− 4 GPa (σ_PUA1 < σ_PUA2 < σ_PUA3 < σ_PUA4) with the increase of PUAs crosslinking density, and the elongation at break is in the range of 140$\sim$160%. In corresponding Fig. 5c, the elastic modulus gradually increases from 8×10⁻⁵ to 1.9×10⁻⁴ GPa (E_PUA1<E_PUA2<E_PUA3<E_PUA4) with the increase of PUAs crosslinking density. As shown in Fig. 5b, after the addition of PEDOT:PSS, the elongation at break of CAPPs is significantly reduced in the range of 90$\sim$110%, and the tensile strength gradually increases from 0.5 to 8.6 MPa (σ_CAPP1 < σ_CAPP2 < σ_CAPP3 < σ_CAPP4). Figure 5c shows that the elastic modulus gradually increases from 2.4 to 22.5MPa (E_CAPP1<E_CAPP2<E_CAPP3<E_CAPP4). The elastic modulus of both PUAs and CAPPs show an increasing trend, and the elastic modulus of CAPP4 are much larger than those of PUA4, about 118 times larger. The elongation at break of CAPP4 is smaller than that of PUA4, about 1.4 times (Fig. 5d). The high elongation at break of PUAs is mainly due to the pore structure, which can absorb a large amount of energy when stressed, thus making PUAs have a high elongation at break. In contrast, the elongation of CAPPs is relatively small. By comparing Fig. 5a, b, c and d, it is found that after adding PEDOTPSS, the elastic modulus of CAPPs increase significantly with the collapse of PUAs pores, while the strain decreases correspondingly. The tensile strength increases with the degree of PUAs pore collapse. CAPP4 has the most serious pore collapse and the maximum tensile strength. Compared the tensile strength of PUA1, PUA2, PUA3, PUA4 with CAPP1, CAPP2, CAPP3 and CAPP4 respectively, they are increased by 3.9, 8.6, 9.3 and 26 times. CAPP4, for example, is shown in Fig. 5e. The four photos demonstrate that CAPP4 with an original length of 40mm can withstand a tensile length of 80mm, a bending 90° and a torsion deformation of 3 turns. This indicates that CAPP4 has good flexibility and tensile stability. The two ends of CAPP4 with a length of 60×2.5×1.5mm are connected with LED and fixed with copper tape. When CAPP4 is integrated into the circuit as a wire, the LED immediately emits light at 2V, 2mA.When CAPP4 is stretched, bent and twisted, the brightness of the LED does not change significantly (Fig. 5f and Video S1). In summary, CAPP4 has good dimensional stability and conductive stability under complex dynamic strain.

3.3 Electrical properties of CAPPs

The electrical properties of CAPP4 are shown in Fig. 6. With the increase of PUAs pore collapse, the resistance of CAPPs decreases from 1365Ω to 40Ω, a significant reduction of 97%, as shown in Fig. 6a. The conductivity of CAPPs is calculated by the following formula[36]:

$$\sigma =\frac{100L}{RA}$$

where L(cm) represents the CAPPs length, R(Ω) is the CAPPs resistance, A(cm^− 2) represents the CAPPs cross-section area, and σ(S/m) is the CAPPs electrical conductivity[36]. As shown in Fig. 6b, the conductivity of CAPP1 is only 12S/m, and there is no significant improvement in conductivity due to insufficient pore collapse. For CAPP2, CAPP3 and CAPP4, their conductivities are 1348, 1537 and 1590S/m, respectively, and CAPP4 has a maximum conductivity. This is achieved with an extremely low PEDOT:PSS load (1.53 wt%). The conductivity and PEDOT:PSS content of elastomers in the published literature were compared with those of CAPP4 (Fig. 6c)[31, 37–41]. In previous studies, most of PEDOT:PSS and polymers are blended or surface-deposited to prepare conductive elastomers, among which Seyedin et al.[31] prepared polyurethane (PU)/PEDOT:PSS elastic fiber composites by wet spinning technology after mixing 13% PEDOT:PSS with PU evenly, with a conductivity of 900S/m. In this study, polyurethane elastomers prepared by aerogel pore collapse method have higher conductivity and lower PEDOT:PSS content than previously reported. Compared with the published literature where the conductivity of PEDOT:PSS content is 30 wt% and the conductivity is 30S/m[39], the conductivity of CAPP4 is 98% higher and the PEDOT:PSS content is 96% lower.

Taking CAPP4 as an example, the mechanism of high conductivity is drawn as shown in Fig. 6d. PEDOT:PSS solution enters the interior of PUA4 along spherical surfaces under the capillary force. During the solvent evaporation, PEDOT:PSS adsorbed on the surface as discussed in the FTIR figure (Fig. 4a), then the pores formed between the spherical PUA4 are not enough to maintain their original shape, and the collapse of the pores after contraction leads to the rapid decrease of the tunnel distance among the spherical surfaces, forming a more closely contacted PEDOT:PSS conductive circuit, which improves the conductivity of CAPP4. Figure 6e shows the resistance change of CAPP4 during cyclic stretching/releasing. The two ends of 60×2.5×1.5mm CAPP4 were connected with conductive silver paste, and the two ends were fixed on the tension machine with PVA insulating tape for cyclic stretching/releasing. The relative resistance change (ΔR/R₀) shows good response to cyclic stretching/releasing under 10% strain. After 5000 cycles of stretching/releasing, ΔR/R₀ is still between 0.6%-1.7%, indicating that CAPP4 can maintain its conductive stability under certain deformation for a long cyclic period.

3.4 ECG signal monitoring of CAPP4

The monitoring of ECG signals is shown in Fig. 7. Figure 7a shows a part of the chest of a human body connected to an electrochemical workstation for monitoring the human ECG. The ECG sensor is composed of conductive hydrogel, CAPP4, gasket and electrode buckle. As part of the electrode composition, CAPP4 is assembled between the conductive hydrogel and the gasket to test the heart vibration state. The three electrodes made are connected to the right upper, left upper and left lower parts of the human chest and abdomen to transmit the ECG signals to the ECG monitor for monitoring (Fig. 7a). Figure 7b and c provide an ECG image showing the ECG signals at different stages. These signals are recorded by the sensor connected to the human chest. By measuring the ECG of adults in different states (Video S2 and S3), Fig. 7b and c are the ECG images tested while sitting quietly and after running for 5 min, with 74 and 99 heartbeats respectively. The electrode assembled with CAPP4 can accurately reflect the ECG signals monitored in the sitting and moving states of the human body. P waves, QRS wave groups and T waves can be clearly identified, and the heartbeat waveforms can be clearly and continuously output. Therefore, CAPP4 can be used as an ECG electrode to reflect the heartbeat of the human body continuously and accurately. In summary, CAPP4 can be used as an electrode for human health monitoring in wearable devices.

PUAs were successfully prepared, and a new feasible pore collapse strategy was used to prepare flexible highly conductive CAPPs. PEDOT:PSS was successfully evenly distributed and adsorbed on CPPAs due to the hydrogen bonding. PEDOT:PSS content in CAPPs was 1.37–1.53 wt%, among which the elastic modulus of CAPP4 was 22.5MPa, the elongation at break was 110%, and the conductivity reached 1590 S/m. The CAPPs connected with LED can withstand stretching/bending/twisting without affecting the brightness of LED. Therefore, the pore collapse method can be used to construct highly conductive composites with low conductive PEDOT:PSS content. Taking CAPP4 as an example, it has good dimensional stability under complex dynamic strain, and the relative resistance change (ΔR/R₀) is still between 0.6% and 1.7% after 50 cycles of stretching/releasing under 10% strain. It can be assembled in the electrode to monitor the human ECG signal, providing a new idea for the development of human health monitoring in wearable devices. Moreover, from the analysis of the preparation processes of PUAs, PEDOT:PSS in CAPPs, a feasible pore collapse strategy provides a new idea for the preparation of flexible highly conductive polyurethane elastomers.

The authors declare no competing financial interests and all data availability without restriction.

Funding

The authors express their thanks to the financial support from the Open Project Program of Tianjin Key Laboratory of Brine Chemical Engineering and Resource Eco-utilization (No. BCERE202205).

Author contributions

Mengxue Sun: Data curation; Formal analysis; Investigation; Graphic preparation; Methodology; Roles/Writing – original draft. Tong Wan: Data curation; Formal analysis; Roles/Writing – revision. Xiaohan Zhu: Formal analysis. Fan Ge: Software. Shubo Liang: Electrocardiogram (ECG) tests. Bowen Xu: Formal analysis, Data Curation, Visualization. Kai Ni: Data curation. Yingying Zhang: Electrocardiogram (ECG) tests.

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Preparation of flexible highly conductive polyurethane elastomers with low PEDOT:PSS content based on novel feasible pore collapse strategy for flexible conductor

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Abstract

Figures

1. Introduction

2 Experimental

2.1 Materials

2.2 Preparation of PUAs

2.3 Fabrication process of CAPPs

2.4 Characterization

3. Results and Discussion

3.1 Characterization of PUAs and CAPPs

3.2 Mechanical properties of CAPPs

3.3 Electrical properties of CAPPs

3.4 ECG signal monitoring of CAPP4

4 Conclusion

Declarations

References

Additional Declarations

Supplementary Files

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