  Immediately before adsorption to a horizontal substrate, sinking
polymer-coated colloids can undergo a complex sequence of landing, jumping,
crawling and rolling events. Using video tracking we studied the soft adhesion
to a horizontal flat plate of micron-size colloids coated by a controlled molar
fraction $f$ of the polymer PLL-g-PNIPAM which is temperature sensitive. We
ramp the temperature from below to above $T_c=32\pm 1^{\circ}$C, at which the
PNIPAM polymer undergoes a transition triggering attractive interaction between
microparticles and surface. The adsorption rate, the effective in-plane ($x-y$)
diffusion constant and the average residence time distribution over $z$ were
extracted from the Brownian motion records during last seconds before
immobilisation. Experimental data are understood within a rate-equations based
model that includes ageing effects and includes three populations: the
untethered, the rolling and the arrested colloids. We show that pre-adsorption
dynamics casts analyze a characteristic scaling function $\alpha (f)$
proportional to the number of available PNIPAM patches met by soft contact
during Brownian rolling. In particular, the increase of in-plane diffusivity
with increasing $f$ is understood: the stickiest particles have the shortest
rolling regime prior to arrest, so that their motion is dominated by untethered
phase.
