Synthesis of Neutral, Water-Soluble Oligo–Ethylene Glycol-Containing Dendronized Homo- and Copolymers of Generations 1, 1.5, 2, and 3
摘要:
Oligo-ethylene glycol-containing dendronized monomers MG1, MG1.5, MG2, and MG3 were synthesized in a particularly easy fashion on the gram scale involving only few steps. Their corresponding homopolymers (PG1, PG1.5, PG2, and PG3) and copolymers (PG1co2, PG1co3, and PG2co3) were synthesized via free radical polymerization. All the polymers are soluble in water and also in organic solvents such as DCM, CHCl3, 1,4-dioxolane, DMF, and DMSO. Their glass transition temperatures (T-g) are in the range -68 degrees C < T-g < -48 degrees C and thus rather low. All polymers show thermoresponsive behavior which was investigated by turbidity measurements. Interestingly, a 1:1 mixture of homopolymers PG1 and PG2 behaves identical with PG1 alone, while the collapse curve of copolymer PG1co2 is almost superimposable with that of PG2 alone. Thus, in the former case PG1 dominates the thermoresponsive behavior while in the latter this is done by the G2-dendrons in the copolymer. Finally, the polymer chains were visualized by AFM, confirming the rod-like behavior of these rigidified polymers.
The reactivityratios for the copolymerization of a first‐generation dendronizedmonomer with styrene and differentacrylates are determined. The obtained ratios as well as the copolymer compositions that can be expected are discussed in detail. The influence of the dendron on the polymerization potential of the monomer is estimated by comparing its reactivity to those of linear systems as well as