A polishing pad for chemical mechanical polishing comprises: a polishing layer that comprises a polymer matrix that is the reaction product of an isocyanate terminated oligomer or polymer with a curative blend comprising a mono-aromatic polyamine curative and a polyamine curative having two or more aromatic rings, wherein the polymer matrix has hard segment domains and soft segment domains wherein pores are present in the polymer matrix, such pores being formed by expansion of pre-expanded fluid filled polymeric microspheres such expansion occurring during reaction of the isocyanate terminated oligomer or polymer with the mono-aryl amine curative and the poly-aryl amine curative, wherein the pores have a unimodal size distribution and wherein the polishing layer has a specific gravity of less than 0.70 g/cm3.