Force-induced desorption of uniform branched polymers

We analyze the phase diagrams of self-avoiding walk models of uniform branched polymers adsorbed at a surface and subject to an externally applied vertical pulling force which, at critical values, desorbs the polymer. In particular, models of adsorbed branched polymers with homeomorphism types, stars, tadpoles, dumbbells and combs are examined. These models generalize the earlier results on linear, ring and 3-star polymers. In the case of star polymers, we confirm a phase diagram with four phases (a free, adsorbed, ballistic, and mixed phase) first seen in Janse van Rensburg and Whittington (2018 J. Phys. A: Math. Theor. 51 204001) for 3-star polymers. The phase diagram of tadpoles may include four phases (including a mixed phase) if the tadpole is pulled from the adsorbing surface by the end vertex of its tail. If it is instead pulled from the middle vertex of its head, then there are only three phases (the mixed phase is absent). For a dumbbell pulled from the middle vertex of a ring, there are only three phases. For combs with t teeth there are four phases, independent of the value of t for all . (paper)