I will explain how to approach the question of $E_2$-formality of differential graded algebras over a prime field via obstruction theory. In particular, $E_2$-algebras whose cohomology ring is a polynomial algebra on even degree classes are intrinsically formal. As a consequence we can prove $E_2$-formality of the classifying space of some compact Lie group or of Davis-Januszkiewicz spaces.
Links:
[1] http://www.mpim-bonn.mpg.de/taxonomy/term/39
[2] http://www.mpim-bonn.mpg.de/node/3444
[3] http://www.mpim-bonn.mpg.de/UHT