Right-hander Drew Carpenter also was sent to Triple-A Lehigh Valley along with Brown. The moves were made before Saturday night's game against Pittsburgh.
Polanco has been out because of a back injury since July 5. He was hitting .274 with four home runs and 39 RBIs entering the night. Polanco was batting seventh instead of his usual No. 2 spot in the lineup.
Brown hit .246 with five homers and 19 RBIs in 54 games for the Phillies this season.