We present and discuss series of experiments conducted on systems controlle
d at the molecular level in order to identify the molecular mechanisms of p
olymer adhesion. A special emphasis is paid to 1) adhesion enhancement thro
ugh block copolymers at an interface between two incompatible polymers (amo
rphous or semi-crystalline); 2) adhesion promotion between an elastomer and
a solid, by soft end grafted connector polymer molecules able to interdigi
tate into the elastomer. We show that surface modifications based on surfac
e anchored polymer chains are efficient for adhesion enhancement because th
ey allow the interface to sustain mechanical stresses. The coupling between
surface and bulk stresses is finally what governs the adhesion energy and
we examine how one can understand and optimize this coupling.