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For the polybutadiene chain in 1,4-dioxane, define $R_x$ from the negative end charge toward the positive one. The electric dipole energy is $-eE{R}_x$, so the force conjugate to end separation is $eE$, even though the two endpoint forces are opposite. Balancing it against the entropic spring force givesNumerically,The zero-field rms of just the $x$ component is $60/\sqrt{3}=34.6\mathrm{nm}$, a different comparison. The mean extension is still much smaller than the contour length $Na=6\mu \mathrm{m}$, consistent with the Gaussian ideal chain force law. This is an end-charged ideal polymer in an electric field; the direct endpoint Coulomb interaction is omitted as stipulated.

Polybutadiene is a polymer derived from 1,3-butadiene. Different addition modes produce cis-1,4, trans-1,4, or 1,2-containing structures, with different spatial arrangements and remaining double bonds.

This microstructure strongly affects flexibility, crystallization, and elastic behavior. The monomer name alone therefore does not specify a unique polymer chain geometry or one set of mechanical properties.