Functionalized acrylic materials derived from methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), and diethyl 2-(methacryloyloxy)ethyl phosphate (DMP) were synthesized by successive free-radical polymerizations using benzoyl peroxide (BPO) as the initiator and N,N-dimethyl-p-toluidine (DMpT) as the activator. NMR and GPC data showed that successful random copolymerization of MMA and DMP was carried out using the BPO-DMpT system. Moreover, the resulting products were able to react with HEMA monomer, yielding polymers with P(MMA-co-DMP)-b-PHEMA chain structures. Interestingly, the glass transition of DMP/PHEMA-containing copolymers was reduced with respect to the PMMA homopolymer. In addition, the thermal stability was enhanced with increasing DMP content in P(MMA-co-DMP) copolymers and was further enforced by incorporating PHEMA blocks. The presence of DMP/PHEMA segments should improve the thermal behavior of acrylic materials, which is of great interest in the design of versatile bone cements for total joint arthroplasty and functional coatings in targeted drug delivery.