Self-assembly of poly(4-methylstyrene)-g-poly(methacrylic acid) graft copolymer in selective solvents for grafts: scattering and molecular dynamics simulation study

Polyzwitterions with LCST Side Chains: Tunable Self-Assembly

Manipulation of self-assembly behavior of copolymers via environmental change is attractive in the fabrication of smart polymeric materials. We present tunable self-assembly behavior of graft copolymers, poly(sulfobetaine methacrylate)-graft-poly[oligo(ethylene glycol) methyl ether methacrylate)-co-di(ethylene glycol) methyl ether methacrylate] (PSBM-g-P(OEGMA-co-DEGMA)). Upon heating the aqueous solutions, the graft copolymers undergo a transition from micelles with PSBM cores to unimers (i.e., individual macromolecules) and then to reversed micelles with P(OEGMA-co-DEGMA) cores, thus demonstrating the tunability of the self-assembling through temperature change. In the presence of salt the temperature response of PSBM is eliminated, and the structure of the micelles with the P(OEGMA-co-DEGMA) core changes. Moreover, for the graft copolymer with long side chains, micelles with aggregation number ∼ 2 were formed with a PSBM core at low temperature, which is ascribed to the steric effect of the P(OEGMA-co-DEGMA) shell.

Self-Assembly of Block and Graft Copolymers in Organic Solvents: An Overview of Recent Advances

This review is an attempt to update the recent advances in the self-assembly of amphiphilic block and graft copolymers. Their micellization behavior is highlighted for linear AB, ABC triblock terpolymers, and graft structures in non-aqueous selective polar and non-polar solvents, including solvent mixtures and ionic liquids. The micellar characteristics, such as particle size, aggregation number, and morphology, are examined as a function of the copolymers' architecture and molecular characteristics.

Polymeric micelles based on poly(methacrylic acid) block-containing copolymers with different membrane destabilizing properties for cellular drug delivery

Poly(methacrylic acid)-b-poly(ethylene oxide) are double hydrophilic block copolymers, which are able to form micelles by complexation with a counter-polycation, such as poly-l-lysine. A study was carried out on the ability of the copolymers to interact with model membranes as a function of their molecular weights and as a function of pH. Different behaviors were observed: high molecular weight copolymers respect the membrane integrity, whereas low molecular weight copolymers with a well-chosen asymmetry degree can induce a membrane alteration. Hence by choosing the appropriate molecular weight, micelles with distinct membrane interaction behaviors can be obtained leading to different intracellular traffics with or without endosomal escape, making them interesting tools for cell engineering. Especially micelles constituted of low molecular weight copolymers could exhibit the endosomal escape property, which opens vast therapeutic applications. Moreover micelles possess a homogeneous nanometric size and show variable properties of disassembly at acidic pH, of stability in physiological conditions, and finally of cyto-tolerance.

Studies on the orthogonal assembly of β-cyclodextrin-poly (ε-caprolactone) and ferrocene-poly (ethylene oxide)

A biodegradable multi-arm polymer β-cyclodextrin-poly (ε-caprolactone) (CD-PCL) with a ``jellyfish-like'' structure was obtained, in which flexible and hydrophobic PCL arms were selectively grafted to the wide side of the hydrophilic torus-shaped β-CD. The amphiphilic "jellyfish-like'' polymer with a hollow cavity and hydrophobic tails could orthogonally self-assemble into a new amphiphilic supramolecular copolymer CD-PCL/FcPEG with poly (ethylene oxide) end-decorated by ferrocene (FcPEG) in aqueous solution based on terminal hydrophobic interactions. The chemical structures of CD-PCL and CD-PCL/FcPEG were characterized by IR, NMR and UV and their self-assembled structures in water were investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS). CD-PCL alone self-assembled into nano vesicles in water, while CD-PCL/FcPEG into nanospheres. The supramolecular nanospheres were further investigated by cyclic voltammogram. The results indicated that the ferrocenyl groups which were embedded into the hydrophobic core of the supramolecular nanospheres could not transmit electrons or carry out electrochemical oxidation and reduction reaction.