Crosslinkable PEO-PPO-PEO triblocks as building blocks of thermo-responsive nanoshells

A series of thermo-responsive nanoshells were generated by shell-crosslinking poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) dimethacrylate triblocks. The nanoshells produced displayed a remarkable and reversible change in size, within a narrow temperature interval. The effect of the concentration of the PEO-PPO-PEO dimethacrylate was studied within the 0.2–4.0 wt% range. Increasing the reaction temperature favored the formation of tubular nanoshells, due to the transformation of the PEO-PPO-PEO micelles from a spherical geometry to rod-like shape at a higher temperature. Blending PEO-PPO-PEO triblocks into the PEO-PPO-PEO dimethacrylate micelles, decreased the crosslink density of the nanoconstructs formed, and resulted in nanoshells attaining larger volumetric differentials. The addition of water soluble organic solvents to the aqueous medium resulted in the increase of the size of the nanoshells and shifted their transition to higher temperatures, whereas increasing the ionic strength of the solution caused the nanoshells to shrink.