Robust, Solvent-Free, Catalyst-Free Click Chemistry for the Generation of Highly Stable Densely Grafted Poly(ethylene glycol) Polymer Brushes by the Grafting To Method and Their Properties

Abstract

Herein we report a robust, highly selective, and efficient method to prepare dense poly(ethylene glycol) (PEG) polymer brushes on silicon substrates via solvent-free, catalyst-free, strain-promoted acetylene−azide cycloaddition (SPAAC) reaction. First, poly(glycidyl methacrylate) was grafted to the silicon substrate as an anchoring layer to immobilize cyclopropenone-caged dibenzocyclooctyne-amine (photo-DIBO-amine) via an epoxy ring-opening reaction providing protected, stable, and functionalized substrates. Next, three synthesized α-methoxy-ω-azido-PEGs of different molecular weights (5, 10, and 20 kg/mol) were successfully grafted to the photo-DIBO-modified silicon substrates from melt after the deprotection of DIBO with UV-irradiation. PEG molecular weight, reaction temperature, and reaction time were all used to control the grafting reaction for targeted brush thicknesses and grafting densities. The highest grafting density obtained was close to 1.2 chains/nm 2 and was achieved for 5 kg/mol PEG. The prepared PEG polymer brushes displayed efficient antifouling properties and stability in PBS buffer aqueous media for a period of at least two months.

Loops and Cycles at Surfaces: The Unique Properties of Topological Polymer Brushes

“…Moreover, recent progresses in the synthesis of cyclic polymers by “ring‐closure” approaches are overcoming the initial difficulties in obtaining cycles in large quantities and high purity, while maintaining experimentally accessible conditions for their preparation . In parallel, constantly growing efforts are being spent in establishing efficient surface‐modification methods for obtaining dense and chemically stable brush interfaces on organic and inorganic supports, including flat and NP substrates …”

“…These include biopassive coatings, cell‐sensitive platforms, lubricating films, stimuli‐responsive devices and sensors, hybrid coatings with distinctive optical, electronic or catalytic properties. Generally, the structural engineering of the polymer assembly, that is, a variation in the molar mass of the grafts or in their surface density, regulates the surface concentration of functionalities and the conformation of the grafted polymer chains. This last parameter is ultimately determined by the enthalpic and entropic balance within the brush, which also governs the steric stabilization provided to the functionalized surface .…”

Assembly of Plasmonic Nanoparticles on Nanopatterns of Polymer Brushes Fabricated by Electrospin Nanolithography

“…Macromolecules that are end-grafted to solid substrates show great promise for a broad range of applications and scientific studies. [1][2][3][4] The strong interest in end-grafted polymers (i.e. polymer brushes) results from the robust interface that can be precisely tuned by the structure and chemistry of the macromolecules which exhibit stimuli responsive behavior.…”

Multifunctional and Transformable ‘Clickable’ Hydrogel Coatings on Titanium Surfaces: From Protein Immobilization to Cellular Attachment

“…Recent years have attracted a lot of interest in employing ‘click’ chemistry tools for multi-functionalization of polymeric materials, due to the efficient nature of these chemical transformations under relatively mild conditions [ 27 , 28 ]. In particular, the Huisgen 1,3-dipolar cycloaddition [ 29 ], strain-promoted (3+2) azide−alkyne cycloaddition [ 30 , 31 ], radical-mediated thiol-ene [ 32 , 33 ] and thiol-yne [ 34 , 35 ] reactions, Michael additions [ 36 ] and Diels–Alder [ 37 , 38 , 39 , 40 ] reactions have been widely used for immobilization of (bio)molecules on a wide variety of polymeric interfaces. Among all ‘clickable’ units, the maleimide functional group attracts attention due to their facile reaction with thiol- and furan-containing molecules under mild conditions [ 41 , 42 , 43 , 44 ].…”