  We conjecture the exact scaling theory for the adsorption of two-dimensional
polymers by using boundary S matrices. We compute the boundary free energy (the
``g-function''), study the flow from adsorbed to desorbed phase, and derive the
crossover exponent and all the geometrical exponents at the transition. More
generally, we solve the special transition in the O(n) model, the polymer case
corresponding to n=0. The n=2 limit appears identical to the ordinary Kondo
problem.
