The supported aqueous-phase catalysis (SAPC) using hydrated interface has been used to synthesize branched polymers (star and graft) of benzyl methacrylate (BnMA) via atom-transfer radical polymerization (ATRP) in the presence of Na-clay supported catalyst in anisole at ambient temperature. The propagation of star poly(BnMA)s using diPENDTA-Br-6, as hexa-functional initiator is confined at the hydrated interface between the support and the liquid medium as evident from the obtained polymers that are catalyst contamination-free, and exhibited moderately narrow molecular weight distributions (M-w/M-n 1.33). The hexa-functionality of synthesized stars is verified by H-1 NMR, the measurement of their intrinsic viscosity ([]), and radius of gyration (R-g). The polymerization was also recycled up to 5 times to produce star PBnMAs with high initiator efficiency. The star polymers prepared using hydrated Na-clay supported is compared with star prepared using covalent silica supported catalyst system. The star polymer obtained from covalently supported catalyst gave broad M-w/M-n and poor initiator efficiency. The polystyrene-graft-PBnMA (PS-g-PBnMA) copolymer is also prepared using hydrated Na-clay supported catalyst system in anisole at ambient temperature. The graft-copolymer had narrow M-w/M-n and was confirmed using H-1 NMR and atomic force microscopy. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2225-2237