Enhanced Dielectric Properties of a Poly(dimethyl siloxane) Bimodal Network Percolative Composite with MXene

Abstract

Excellent comprehensive dielectric properties (including dielectric constant and loss) are essential for electromechanical transducers. This work introduced a bimodal network composite with poly­(dimethyl siloxane) (PDMS) and delaminated Ti3C2T x sheets (d-Ti3C2T x ) modified with hyperbranched polysiloxane (HPSi) (referred to as HPSi-d-Ti3C2T x ). Before the final cross-linking, HPSi-d-Ti3C2T x , trapped with short-chain PDMS (CS-PDMS) and long-chain PDMS (CL-PDMS), was pre-reacted, which formed a distinct bimodal network structure. d-Ti3C2T x /PDMS and HPSi-d-Ti3C2T x /PDMS composites with different filler loadings were prepared, and their percolation thresholds (f c) were 1.32 and 1.43 vol %, respectively The dielectric constant of 1.40 vol % HPSi-d-Ti3C2T x /PDMS is 23.7 at 102 Hz, which is 1.5 times that of 1.28 vol % d-Ti3C2T x /PDMS and 8.5 times that of pure PDMS. Meanwhile, the dielectric loss of HPSi-d-Ti3C2T x /PDMS composite is still relatively small (0.11 at 103 Hz). The origin of dielectric property optimization of the composite is attributed to the boundary capacitor model, the accumulated charges at the interfaces between the conductive filler and the insulating polymer matrix of the composite, and the distinct bimodal network structure.

Electreted Sandwich Membranes with Persistent Electrical Stimulation for Enhanced Bone Regeneration

“…Subsequently, the composite membranes were polarized and electreted. PDMS is a common dielectric material that is widely used in the energy, electrical, and sensing fields. , In the present study, PDMS was chosen as the encapsulation layer to eliminate the effect of the liquid environment (such as the cell culture medium or tissue fluid) on the polarization effect of SiO 2 electrets, as well as to conduct the electrical potential. , Moreover, PDMS and SiO 2 are well compatible, which is conducive to the dispersion of SiO 2 electrets in the PDMS matrix and the fabrication and modeling of sandwich-like composite membranes . By adjusting the concentration of incorporated SiO 2 nanoparticles (1, 2, and 3 wt %), a set of S/P and E-S/P composite membranes was fabricated.…”

Well-Dispersed Nanocomposites Using Covalently Modified, Multilayer, 2D Titanium Carbide (MXene) and In-Situ “Click” Polymerization

“…It is well-recognized that the bulk properties of nanocomposites are highly dependent on the nanomaterial’s dispersion . The large surface area of nanomaterials provides improved nanocomposite properties at low loadings but simultaneously renders them prone to aggregation. , Aggregation has been identified as one of the greatest obstacles facing nanocomposite research regardless of the chosen nanomaterial or intended application. − Recently, researchers have focused on the surface modification of MXenes ,,− to improve their compatibility with solvents, monomers, and polymers, which has promise for facilitating the bulk synthesis of well-dispersed MXene–polymer NCs. Toward this goal, Ti 3 C 2 T z MXenes have been covalently modified by reacting −OH surface terminations with alkylsilanes, ,− alkylphosphonic acids, carboxylic acids, and isocyanates .…”

Stretchable conductors for stretchable field-effect transistors and functional circuits

“…166 However, the gate dielectrics built in intrinsic s-FETs require not only excellent mechanical flexibility but also high permittivity. 154,167,168 For example, the interfacial polarization of poly(thioether) and polysiloxane is enhanced by the phase separation structure of the triblock copolymer, thereby improving the dielectric constant. 169 Furthermore, to obtain acceptable insulating strengths for the applications of gate dielectric, films of more than 300 nm are typically needed.…”