Polyethylene end functionalization using thia-Michael addition chemistry

Abstract

International audienceThiol end functionalized polyethylenes (PE-SH, Mn around 1000 g mol−1, Đ \textless 1.3) were used as nucleophiles in thia-Michael additions with different acrylic molecules. It was found that under commonly used practical conditions the addition to methacrylates was very difficult, whereas addition to acrylates was very efficient. First, block copolymers based on PE and poly(methyl methacrylate) (PMMA) were targeted by reaction of PE-SH with PMMA obtained by catalytic chain transfer polymerization (CCTP). The reaction however failed and detailed model experiments using butanethiol and a dimer of MMA showed that the solubilization temperature of PE-SH was an impediment to the success of the reaction. The lack of reactivity towards PMMA obtained by CCTP and methacrylate functions was advantageously used to react molecules containing both an acrylate and a methacrylate group in the presence of tributyl phosphine (PBu3) to produce methacrylate-type PE macromonomers. The presence of a hydroxyl function on 3-(acryloyloxy)-2-hydroxypropyl methacrylate induced side trans-esterification reactions catalyzed by PBu3. This was overcome by using the hydroxyl free 2-(acryloyloxy) ethyl methacrylate. With the latter, the desired PE macromonomer exhibited a functionality as high as 85%. Alternatively, 2-isocyanatoethyl methacrylate could also be reacted with PE-SH to produce a highly functionalized methacrylate type PE macromonomer (functionality 89%). Eventually, the efficiency of the thia-Michael addition of PE-SH onto poly(ethylene glycol) acrylate (PEG-acrylate) was used to synthesize the PE-b-PEG block copolymer

Polymerization-Induced Self-Assembly of Galactose-Functionalized Biocompatible Diblock Copolymers for Intracellular Delivery

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Cathepsin B cleavable novel prodrug Ac‐Phe‐Lys‐PABC‐ADM enhances efficacy at reduced toxicity in treating gastric cancer peritoneal carcinomatosis

“…In our system, the RAFT groups double as the chain ends in our branching scheme and can be easily cleaved via aminolysis 33, 40. The remaining thiols can then be modified through thiol‐Michael addition chemistry 41–43…”

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“…3a). 24,25 These compounds are separately dissolved in a variant of the standard nematode growth medium (NGM; see Methods) with the pH adjusted to 6.3 in order to facilitate the Michael chemistry (standard NGM is pH 6.0). The solutions are mixed at a stoichiometric ratio to yield a final concentration of 8.5% w / v PEG, and dispensed into the frame/slide apparatus under a separate glass coverslip.…”