The synthesis of star-like A(B)n copolymers based on the hydrophilic poly(ethylene glycol) monomethyl ether (m-PEG, block A) and the hydrophobic poly(methyl methacrylate) (PMMA, blocks B) is reported. We obtained copolymers made of one m-PEG chain and 2 or 4 PMMA blocks using a combined “arm first”- “core first” approach. Such structures were called tree-shaped copolymers where the m-PEG was considered as the trunk and PMMA arms as the branches. Star-like copolymers (B)nA-A(B)n built by two tree-shaped fragments with a poly(propylene oxide) (PPO) as the central junction, were also synthesized according to a previously reported procedure. The latter were called star-shaped structures and the synthesis was performed to obtain architectures different from the tree-shaped one but characterized by a similar length of the PMMA arms. Microstructural analysis was carried out through 1H-NMR and GPC, and the thermal and transport properties (sorption and diffusion) to liquid water were investigated and correlated to the molecular architecture of the two classes of copolymers.