One‐Reactant Photografting of ATRP Initiators for Surface‐Initiated Polymerization

Abstract

Self-initiated photografting polymerization is used to couple the polymerizable initiator monomer 2-(2-chloropropanoyloxy)ethyl acrylate to a range of polymeric substrates. The technique requires only UV light to couple the initiator to surfaces. The initiator surface density can be varied by inclusion of a diluent monomer or via selection of initiator and irradiation parameters. The functionality of the initiator surface is demonstrated by subsequent surface-initiated atom transfer radical polymerization. Surfaces are characterized by x-ray photoelectron spectroscopy (XPS), ellipsometry, and atomic force microscopy (AFM), and UV-induced changes to the initiator are assessed by (1) H NMR and gel permeation chromatography (GPC). This is the first time this one-reactant one-step technique has been demonstrated for creating an initiator surface of variable density.

Nano‐Star‐Shaped Polymers for Drug Delivery Applications

“…ATRP is an example of a technique used to attain living polymerization, and it functions on the formation of radicals from dormant alkyl halides by halogen abstraction with transition metal complexes. [24,[75][76][77][78][79][80][81][82][83] This method hinges on the fact that the equilibrium in this reaction lies largely on the side of the dormant alkyl halides, meaning that the number of radicals produced is few. This translates into a lower radical concentration, and reduces the possibility of radical termination reactions to maintain the living polymerization of the arms of these star-shaped polymers, or other polymers for that matter.…”

“…ATRP is an example of a technique used to attain living polymerization, and it functions on the formation of radicals from dormant alkyl halides by halogen abstraction with transition metal complexes . This method hinges on the fact that the equilibrium in this reaction lies largely on the side of the dormant alkyl halides, meaning that the number of radicals produced is few.…”

Long-Term Maintenance of Human Pluripotent Stem Cells on cRGDfK-Presenting Synthetic Surfaces

“…An OCT4-mCherry reporter cell line was generated from the human embryonic stem cell line H9 to screen PAAA and PAPA coatings modified with test peptides for adhesion and short-term maintenance of hPSCs. Briefly, the copolymer coatings were prepared using an initiator-free UV-activated surface grafting method 5 , 6 that prepared surface-initiated polymer brush coatings, to which peptides were chemically coupled using either water soluble carbodiimide chemistry (for lysine-terminated peptides) 7 or Cu(I) mediated azide-alkyne Huisgen cycloaddition (for azide-terminated peptides) 8 . In our hands these surfaces were also able to maintain adherent cultures of mesenchymal stem cells and L929 fibroblasts (data not shown).…”

“…The approach outlined in Fig. 2 was used to screen for hPSC adhesion to 23 peptide-modified PAAA coatings, which had been prepared using 40 passes under a high intensity UV light source (PAAA-40UV) and to 14 peptide-modified PAPA coatings that had been synthesised with 30 UV passes (PAPA-30UV) 5 , 6 . The full list of peptides is provided in Supporting Information Table S1 , with chemical properties regarding solubility described in Supporting Information Table S2 .…”

Polymerization Rate Modulated by Tetraarylborate Anion Structure: Direct Correlation of Hammett Substituent Constant with Polymerization Kinetics of 2-Hydroxyethyl Methacrylate

“…Other controlled/living radical polymerization (CLRP) techniques such as atom transfer radical polymerization (ATRP), − reversible addition–fragmentation chain transfer polymerization (RAFT), ,− and nitroxide-mediated polymerization (NMP) − have been used in visible-light-mediated polymerization for the synthesis of polymers and materials with spatial and temporal control. However, an efficient and controlled photoreaction is not so trivial, and the absence of information about photochemical mechanisms, rate constant of electron transfer, and characterization of transient species is detrimental.…”