Poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) homopolymers with low polydispersities were synthesized by reversible addition fragmentation chain transfer (RAFT) radical polymerization. The performances of two chain transfer agents, 2-cyanoprop-2-yl dithiobenzoate and 4-cyanopentanic acid dithiobenzoate (CPADB), were compared. It was found that the polymerization of 2-(diethylamino) ethyl methylacrylate was under good control in the presence of CPADB with 4,4'-azobis(4-cyanopentanoic acid) (ACPA) as initiator in 1,4-dioxane at 70 degrees C. The kinetic behaviors were investigated under different CPADB/ACPA molar ratios. A long polymerization inhibition period was observed at high [CPADB]/[ACPA] ratio. The influences of [CPADB]/[ACPA] ratio, monomer/[CPADB] ratio, and temperature were studied with respect to monomer conversion, molecular weight control, and polydispersity index (PDI). The PDI decreased from 1.21 to 1.12, as the CPADB/ACPA molar ratio changed from 2 to 10. The molecular weight of PDEAEMA could be controlled by monomer/CPADB molar ratio. The control over MW and PDI was improved as the temperature increased from 60 to 70 degrees C however, an additional increase to 80 degrees C led to a loss of control. Using PDEAEMA macroRAFT agent, pH/thermo double-responsive block copolymers of PDEAEMA and poly(N-isopropylacrylamide) (PDEAEMA-b-PNIPAM) with narrow polydispersity (PDI, 1.24) were synthesized. The lower critical solution temperature of PDEAEMA-b-PNIPAM block copolymer depended on the environmental pH. (C) 2008 Wiley Periodicals, Inc.