[2] Poénaru defended his Thèse d'État at the University of Paris on March 23, 1963.

His dissertation topic was Sur les variétés tridimensionnelles ayant le type d'homotopie de la sphère S3, and was written under the supervision of Charles Ehresmann.

Poénaru has worked for several decades on a proof of the Poincaré conjecture, making a number of related breakthroughs.

On December 19, 2006, he posted a preprint to the arXiv, claiming to have finally completed the details of his approach and proven the conjecture.

His friend the Peruvian painter Herman Braun-Vega made of him a family portrait with his wife the painter Rigmor Poenaru, where figures and mathematical symbols in the form of graffiti evoke his research works.