It is prohibited for a man to marry the daughters of his ex-wife; he is considered a Mahram to all her daughters. Allah (Exalted be He) says:
Forbidden to you (for marriage) are: your mothers
until He says:
...your step daughters under your guardianship, born of your wives to whom you have gone in
However, if they had not consummated the marriage, he is not considered a Mahram to her daughters, as Allah (Exalted be He) says:
...but there is no sin on you if you have not gone in them (to marry their daughters)
(Part No. 17; Page No. 347) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.