= Solution
For the usual interpretation of a real chain in a <good solvent>, the detachment <force> is \b[smaller] in the weak-<adsorption> regime. <Excluded volume> swells the chain, increasing the cost of confinement near the substrate. The adsorbed layer becomes thicker and its binding <free energy> per <monomer> decreases. The same contact <energy> therefore does not mean the same total binding strength.
The scaling argument can include both adsorption and stretching. Let $\xi\sim bg^\nu$, where $\nu=1/2$ for an <ideal chain> and approximately $3/5$ for a <self-avoiding walk> in three dimensions. With the same contact-fraction approximation,
$$
\frac{F_{\mathrm{ads}}}{Nk_BT}\sim
\left(\frac b\xi\right)^{1/\nu}-\epsilon\frac b\xi.
$$
Minimization gives $\xi/b\sim\epsilon^{-\nu/(1-\nu)}$ and $\mu/(k_BT)\sim\epsilon^{1/(1-\nu)}$. At detachment, a <tensile blob> of size $\xi_t\sim k_BT/f$ costs approximately $k_BT$; its <monomer> count is $g_t\sim(\xi_t/b)^{1/\nu}$. Equating the stretching gain per <monomer> $k_BT/g_t$ to $\mu$ gives
$$
f\sim\frac{k_BT}{b}\left(\frac{\mu}{k_BT}\right)^\nu
\sim\frac{k_BT}{b}\epsilon^{\nu/(1-\nu)}.
$$
Thus $f_{\mathrm{real}}\sim(k_BT/b)\epsilon^{3/2}$, compared with $f_{\mathrm{ideal}}\sim(k_BT/b)\epsilon$, so their ratio scales as $\epsilon^{1/2}<1$ for weak attraction. These are scaling relations, not exact prefactors. The real-chain adsorption exponents here use the same simple uniform-contact model as the earlier parts; a more detailed surface theory of <critical phenomena> can refine them. The thicker, more weakly bound layer reflects the higher cost of confining a <good solvent> chain.https://dasher.wustl.edu/bio5357/readings/rubinstein-chapter3.pdf[Rubinstein and Colby, Polymer Physics, chapter 3, equations (3.59)–(3.66)]{ref}
“Real” alone does not specify <solvent> quality: a collapsed chain in a poor <solvent>, strong adsorption, or substantial bending stiffness requires a different comparison. The smaller-force conclusion concerns the flexible <good solvent> chain implicit in the excluded-volume correction.
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