Morphology Transition of Dual‐Responsive ABC Terpolymer in Water: Effect of Hydrophobic Block

Abstract

To reveal the importance of hydrophobic block in morphology transition of responsive copolymers, four well‐defined ABC terpolymers with the same poly(dimethylamino ethyl methacrylate) (PDMAEMA) and PEG segments are synthesized by sequential RAFT polymerization. Poly (n‐hexyl methacrylate) (PnHMA), poly(n‐butyl methacrylate) (PnBMA), poly(ethyl methacrylate) (PEMA), and poly(methyl methacrylate) (PMMA), with glass transition temperatures of −5, 20, 65, and 100 °C, respectively, are selected as hydrophobic segments. The structures and compositions of four terpolymers, that is, mPEG45‐b‐PnHMA29‐b‐PDMAEMA28(EHD), mPEG45‐b‐PnBMA28‐b‐PDMAEMA32 (EBD), mPEG45‐b‐PEMA31‐b‐PDMAEMA30 (EED), and mPEG45‐b‐PMMA30‐b‐PDMAEMA29 (EMD), are confirmed by gel permeation chromatography and 1H NMR. Their morphology transitions in water are investigated via a combination of UV‐vis spectroscopy, light scattering, zeta potential measurements, and cryogenic transmission electron microscopy. All terpolymers can form spherical micelle by direct dissolution in acidic water. However, the spherical micelles of EBD and EHD progressively switch to cylinders and vesicles upon variations of external pH and temperature. In contrast, the spherical micelles of EMD and EED reversibly form larger aggregates when the temperature is above the cloud point of PDMAEMA in basic water. This study demonstrates the importance of hydrophobic block on the morphology transition of responsive copolymers.

Synthesis and Thermoresponsive Properties of Biocompatible and Biodegradable Triblock Copolymers Bearing Linear or Y‐Shaped OEG Pendants

“…Nevertheless, the FESEM indicated that both 6a and 6b self‐assembled into spherical micelle in DI water at temperatures below the T cp . Spherical micelle self‐assembled from thermoresponsive block copolymers have also been revealed in previous reports . The diameters of different polymer systems are distinct which is highly related to the structure parameters as well as solution conditions.…”

Effect of Hydrophilic Monomer Distribution on Self‐Assembly of a pH‐Responsive Copolymer: Spheres, Worms and Vesicles from a Single Copolymer Composition

“…Amphiphilic copolymers containing ionizable groups such as carboxylic acids and amines form aw ide range of selfassembled structures in response to changes in pH. [4][5][6] Tr ansitions from unimeric solutions to spherical micelles are common, [7,8] while with careful control of the hydrophilichydrophobic balance of the copolymer, transitions from spherical micelles to wormlike micelles [9][10][11] and/or vesicles [12][13][14][15] may also be observed.…”

Electrostatic‐driven self‐assembled silica aerogel/tethacryloxyethyltrimethyl ammonium chloride/PMMA ternary nanocomposite with thermal insulation phase interfaces

“…The samples were heated from room temperature to 220°C under air atmosphere. According to the DSC results, the glass transition temperature ( T g ) [39] of the samples are summarised in Table 2. Since silica aerogel nanoparticles do not bear any transitions in this range of temperature, therefore only the thermal transition of copolymers is observed.…”