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.
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