Surfactant-Mediated Crystallization-Driven Self-Assembly of Crystalline/Ionic Complexed Block Copolymers in Aqueous Solution

Abstract

A series of crystalline/ionic complexed block copolymers (BCPs) with various compositions have been prepared by sequential reactions. The BCPs with different hydrophilic fractions can self-assemble into various morphologies, such as spindlelike, rodlike, and spherical micelles with different crystallinity of the core. Bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) is added as a surfactant to induce the morphological transition of BCPs in aqueous media. The introduced AOT can be tightly bound to the cationic units, and a water-insoluble unit in the corona forms, leading to a reduced tethering density. Consequently, morphological variety changing from rods to platelets to fibril to dendrite-like micelles can be observed.

Recent progress in block copolymer crystallization

“…The rigidity of the mesogenic portion imparts the rod‐like chain structure. Here, crystallization of the coil block is influenced by the phase behavior of the ordered microphase separation as well as the rigidity of the LC block . LC properties of these materials will not be discussed.…”

“…Steric interaction of LC block mesogens provides long persistence lengths that give the LC block rigid, rod‐like properties similar to conjugated polymer backbones. Some studies have been performed looking at the influence of these LC blocks on the crystallization of PCL blocks, PEO blocks, and PLLA …”

“…LC interactions of the second block were shown to influence PCL crystallization both in the bulk and in solution . Poly(2,5‐bis[4‐methoxyphenyl]oxycarbonyl)styrene)‐ b ‐PCL (PMPCS‐ b ‐PCL) was studied to evaluate the influence of lamellar “hard” confinement ( T g PMPCS = 110°C) on PCL crystallization, crystal orientation, and melting temperature .…”

“…Self‐assembled morphologies of q PDM/MO‐ b ‐PCL (A) w PCL = 0.65, (B) w PCL = 0.54, and (C) w PCL = 0.36 (top) TEM images, (middle) SAED patterns, and (bottom) HRTEM images with fast Fourier transform image insets. (Reproduced from with permission from the American Chemical Society)…”

“…A study of PEO in a BCP with LC behavior, where LC structure was induced by complexation of 2‐(3′,4′,5′‐tris(octyloxy)benzamido)propanoic acid (TOBPA) ligand with P2VP, showed phase separation induced by the LC ordering of the amorphous P2VP phase during complex formation between the ligand and P2VP, a somewhat opposite effect compared to q PDM/MO‐ b ‐PCL with AOT . The pure P2VP‐ b ‐PEO ( w PEO = 0.60) exhibited minimal PEO crystallization due to the miscibility and hydrogen bonding between the blocks .…”