Investigating Structural Effects of Quaternizing Additives on Shape Transitions of Block Copolymer Particles
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초록
내용
In this work, we investigate the shape-changing capabilities of poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) BCP particles upon quaternization with a series of bromoalkyl benzene additives with different alkyl spacer lengths. The bromoalkyl benzene additives exhibit different hydrolyzing and quaternizing behaviors depending on their chemical structures. When benzyl bromide (BB) is used, the PS-b-P2VP BCP particles exhibit a dramatic shape transition from ellipsoids to swelled buds, and vesicles. These morphological transitions are attributed to the synergistic quaternization and protonation of the P2VP chains via the hydrolysis of BB in aqueous media. When the additives contain longer alkyl spacers (e.g., ethyl, butyl, and hexyl), the additives lead to a narrower range of quaternization-dependent particle morphologies due to the absence of the hydrolysis of the additives.