Different communication frameworks have been proposed to describe the mutual interactions and the opinion dynamics on social networks. Opinion formation is a complex process and a realistic description should also take into account the feedback that the opinion of the agents has on the structure of the network and on the dynamics of the opinion itself. I propose a model in which different kinds of interconnections and of interacting behaviours are associated to the agents depending on their opinion: extremists tend to self-segregate but, on the other hand, have a stronger capacity to convince other agents. The system is fully described by a static and a dynamic parameter, and, in the space of parameters a curve delimiting the two different possible scenarios can be drawn: a phase transition appears separating an ordered, consensus, phase from a pluralistic situation. Pluralism can only be achieved when extremists are not self-segregating and their tolerance threshold is high.