To find out why the carbon chain breaks away from self-restraint to an open chain with direction and what happens to the interaction between water molecules and the carbon chain with the electric field, we select one part of the carbon chain with specific bending angle
θ for analysis, as shown in figure
3(b)(I). We define the dipole (
θ) as the angle formed by the dipole moment of the water molecule and the reverse direction of the electric field, as shown in figure
3(b)(II). The direction of the carbon chain is defined as the direction of the connection between the first and the last carbon atoms. For the electric field-free case at the bend location, the oxygen atom of the water molecule is toward the carbon atom of the chain, while the hydrogen atoms of the water molecule are far away from the carbon atom, as shown in figure
3(b)(III). When an electric field is applied, the water molecule will obtain a torque as,
M =
E ×
P, [
40,
62] where
P is the dipole moment of water molecule and
E is the applied electric field. The torque can be rewritten as,
M = −
P Esin
θ. The dipole direction of the water molecule will turn to the direction of the electric field [
40,
41,
59,
62]. In addition, the electrostatic energy of the dipole moment is calculated as
W = −
P ·
E. The electrostatic energy of the dipole moment can be rewritten as,
W = P E cos
θ. When the angle
θ is 180°, the electrostatic energy is the minimum, as shown in figure
3(b)(IV). In other words, when the direction of the dipole moment is along the direction of the electric field, the water molecule is the most stable. Applying an electric field will cause the rotation of the water molecule dipole, which induces a torque, resulting in the extension of the carbon chain.