Soft nanoparticles assembled from linear poly(ethylene glycol) and linear brush polydimethylsiloxane diblock copolymers

Abstract

A series of novel amphiphilic diblock copolymers composed of hydrophilic linear poly(ethylene glycol) (PEG) and linear brush hydrophobic polydimethylsiloxane (PDMS) were synthesized. Three different molecular weights of monomethyl ether PEG were initially functionalized with 2-bromoisobutyryl bromide to afford macroinitiators suitable for atom-transfer radical polymerization. The macroinitiators were characterized by gel permeation chromatography, 1 H and 13 C nuclear magnetic resonance spectroscopic analysis and matrix-assisted laser desorption ionization time-of-flight mass spectroscopy. The three different molecular weight macroinitiators were then chain extended with monomethacryloxypropyl-terminated PDMS and photoactive 2-(methylacyloyloxy)ethyl anthracene-9-carboxylate in different molar ratios to afford a series of photoresponsive amphiphilic diblock copolymers with high conversions. Self-assembly of these linear-linear brush diblock copolymers in N,N-dimethylformamide afforded nanoparticles with hydrodynamic diameters (d H ) ranging from 41 to 268 nm, as determined by dynamic light scattering analysis. Crosslinking and stabilization of the nanoparticles was achieved via [414] photodimerization of the anthracene moieties upon exposure to UV radiation at 365 nm with the reverse reaction studied at a wavelength of 254 nm. Transmission electron microscopy revealed that the self-assembled nanoparticles and their crosslinked derivatives had spherical morphologies.

Synthesis of bottlebrush copolymers based on poly(dimethylsiloxane) for surface active additives

“…The properties and target applications of bottlebrushes are primarily determined by the composition of the side-chain polymers, as they shield the backbone and are generally flexible and able to interact with their environment. Bottlebrush polymer macromolecules range in size from tens to hundreds of nanometers, may be spherical or elongated in shape, 1 and can be designed for applications including stimuli responsive films, 2 nanolithography, 3 drug delivery, [4][5][6] and lubricants, [7][8][9] as discussed in a recent review. 10 A potential application of bottlebrush polymers is as specialty additives to modify polymer film surface properties.…”

Produce Molecular Brushes with Ultrahigh Grafting Density Using Accelerated CuAAC Grafting-Onto Strategy

“…Molecular brushes or graft polymers with very high grafting density have an interesting macromolecular architecture that consist of a linear backbone and numerous side chains (SC). − The polymer often adapts a wormlike conformation, representing an important type of one-dimensional nanostructure. Their compact structure and persistent cylindrical shape give molecular brushes lots of applications in nanotechnology, including sensors, nanomedicine drug delivery, self-healing coatings, and photoresponsive materials. − …”

Synthesis of Poly(OEOMA) Using Macromonomers via “Grafting-Through” ATRP

“…Atom transfer radical polymerization (ATRP) is a powerful reversible-deactivation radical polymerization (RDRP) technique. − ATRP allows for the polymerization of a wide range of monomers, forming copolymers with predetermined molecular weight (MW), narrow molecular weight distribution (MWD), and controlled molecular architecture such as block, gradient, hyperbranched, graft, comblike, and star copolymers. − , ATRP has been conducted in many organic solvents in the presence of various functional groups. Recently, macromonomers (MMs) were used for the preparation of functional graft copolymers via an ATRP “ grafting-through ” method. − Branched polymers such as stars and graft copolymers generally have lower viscosity than polymers with linear structures of the same MWs because of their smaller hydrodynamic volume. − Because of their structural tunability, such as copolymer composition, backbone or side chain length, and grafting density, they have many potential applications. − MMs with hydrophilic and biocompatible properties, such as those based on poly­(ethylene glycol) (PEG), have been used for biomedical applications. , …”