We observed that a triblock copolymer (PEG12-PCL24-PEG12) is more hydrophilic than diblock (PEG12-PCL12). Micelles prepared from the diblock copolymers were less stable and aggregated much faster.
I guess the answer is related with hydrodynamic volume, besides micelles stability.
Hydrodynamic volume increase much faster in case of diblock copolymer. It seems that increase in hydrodynamic volume and less stability is in fact a result higher hydophobicity.
Dear All;
this is simply related to the hydrophilicity of the copolymers. I guess you are talking about a triblock copolymers where the outer blocks are hydrophilic, in case you reverse the situation, i.e., the outer blocks are hydrophobic then you will see the inverse, i.e., the diblock copolymer will be more hydrophilic.
for ordinary multiblock copolymers the influence of the hydrodynamic volume is minor since the length of the chain is moderately low. Regards
Thanks.. Abdelkader for your answer. If A block is hydrophilic in nature, ABA block copolymer will be more hydrophobic(low CMC) compared to BAB as per monte carlo simulation peformed by Kim et al. (A Monte Carlo Simulation for the Micellization of ABA- and BAB-Type Triblock Copolymers in a Selective Solvent,Macromolecules 2001, 34, 7210-7218). However, this simulation does not consider other important hydrophobicity controlling factors such as crystallinity. In our case, we used hexamethylene diisocyanate(HMDI) as a coupling agent (PEG12-PCL12-HMDI-PCL12-PEG12). It seems that in this case it is also playing a critical role in addition with crystallinity of PCL block.
in your case hydrophilic part (PEG) is higher than hydrophobic part so its showing more hydrophilic nature
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