Thermo-Induced Self-Assembly of Responsive Poly(DMAEMA-b-DEGMA) Block Copolymers into Multi- and Unilamellar Vesicles

Abstract

A series of thermoresponsive diblock copolymers of poly [2-(dimethylamino)ethyl methacrylate-block-di(ethyleneglycol) methyl ether methacrylate], poly(DMAEMA-b-DEGMA), were synthesized by reversible addition−fragmentation chain transfer (RAFT) polymerizations. The series consist of diblock and quasi diblock copolymers. Sequential monomer addition was used for the quasi diblock copolymer synthesis and the macro-chain transfer approach was utilized for the block copolymer synthesis. The focus of this contribution is the controlled variation of the ratios of DMAEMA to DEGMA in the copolymer composition, resulting in a systematic polymer library. One of the investigated block copolymer systems showed double lower critical solution temperature (LCST) behavior in water and was further investigated. The phase transitions of this block copolymer were studied in aqueous solutions by turbidimetry, dynamic light scattering (DLS), variable temperature proton nuclear magnetic resonance ( 1 H NMR) spectroscopy, zeta potential, and cryo transmission electron microscopy (cryo-TEM). The block copolymer undergoes a two-step thermo-induced self-assembly, which results in the formation of multilamellar vesicles after the first LCST temperature and to unilamellar vesicles above the second LCST transition. An interplay of ionic interactions as well as the change of the corresponding volume fraction during the LCST transitions were identified as the driving force for the double responsive behavior.

Polymeric Microtubules That Breathe: CO2‐Driven Polymer Controlled‐Self‐Assembly and Shape Transformation

“…Several successful studies have demonstrated, by fluctuating environmental parameters such as osmosis, pH, temperature, light, redox, and shear force, [5][6][7][8][9] that block copolymer aggregates display stimuli-responsive biphase or multiphase transition. However, exogenous stimulation conditions that the majority of reports focused on probably cause potential side effects to biological cells, including incompatibility, cytotoxicity, membrane decomposition, and gene damage.…”

Thermo‐Induced Double Phase Transition Behavior of Physically Cross‐Linked Hydrogels Based on Oligo(ethylene glycol) methacrylates

“…[ 28,29 ] Subsequently, a variety of polymer brushes, micelles, vesicles, micro/nanogels, as well as a few of smart hydrogels based on POEGMA have been developed in the past few years. [30][31][32][33] For instance, Huck and co-workers reported that surface attached P(MEO 2 MA -co-OEGMA) brushes exhibited a fast and reversible thermo-induced collapse transition, resulting in different surface properties of the polymer coating below and above the LCST. [ 34 ] Roth et al showed that POEGMA based copolymers also exhibit a UCST behavior in alcohol/ water mixtures.…”

Thermo-responsive block copolymers with multiple phase transition temperatures in aqueous solutions

“…responsive poly(2-(dimethylamino)ethyl methacrylate)-b-poly(di(ethyleneglycol) methyl ether -b-PDEGMA)) at ∼50:50 (wt %) formed multilamellar vesicles above the LCST of PDEGMA and unilamellar vesicles above the LCST of partially protonated PDMAEMA block in deionized water[131]. PDMAEMA is known to show pH-, molar mass-, and ionic strength-dependent thermo-responsiveness in aqueous solutions.…”