We performed dynamic Monte Carlo simulations of diblock copolymers to investigate how the selective solvents on two blocks can suppress the crystallization-driven fibril self-assembly growth in dilute solutions. We found that either a lower hydrophilicity of the surrounding amorphous block or a lower hydrophobicity of the core crystallizable block can effectively reduce the fibril growth rates. Their mechanisms are different: the former is the shielding effect and the latter is the thermodynamic effect. We discussed the potential correlation of our results to the recent progress of drug discovery for the Alzheimer's disease that elongates the fibril structure of amyloid proteins as a consequence of crystallization of hydrophobic segments under nano-confinement of those hydrophilic segments. Our observations shed light onto the physicochemical background for the basic therapy strategy of protein-misfolding diseases. (c) 2018 Elsevier Ltd. All rights reserved.