New Aldehyde‐Functional Methacrylic Water‐Soluble Polymers

Abstract

Aldehyde groups enable facile conjugation to proteins, enzymes, oligonucleotides or fluorescent dyes, yet there are no literature examples of water‐soluble aldehyde‐functional vinyl monomers. We report the synthesis of a new hydrophilic cis‐diol‐based methacrylic monomer (GEO5MA) by transesterification of isopropylideneglycerol penta(ethylene glycol) using methyl methacrylate followed by acetone deprotection via acid hydrolysis. The corresponding water‐soluble aldehyde monomer, AGEO5MA, is prepared by aqueous periodate oxidation of GEO5MA at 22 °C. RAFT polymerization of GEO5MA yields the water‐soluble homopolymer, PGEO5MA. Aqueous periodate oxidation of the terminal cis‐diol units on PGEO5MA at 22 °C affords a water‐soluble aldehyde‐functional homopolymer (PAGEO5MA). Moreover, a library of hydrophilic statistical copolymers bearing cis‐diol and aldehyde groups was prepared using sub‐stoichiometric periodate/cis‐diol molar ratios. The aldehyde groups on PAGEO5MA homopolymer were reacted in turn with three amino acids to demonstrate synthetic utility.

Adsorption of Aldehyde-Functional Diblock Copolymer Spheres onto Surface-Grafted Polymer Brushes via Dynamic Covalent Chemistry Enables Friction Modification

“…A PGEO5MA 34 (or GO 34 ) precursor was first synthesized via RAFT solution polymerization of GEO5MA in ethanol at 70 °C using a non-ionic trithiocarbonate chain transfer agent, following a similar experimental protocol to that previously reported by our group (Scheme S2). 32,33 A final GEO5MA conversion of 86% was achieved after 180 min, as determined by 1 H NMR analysis in CD 3 OD. End-group analysis of the purified PGEO5MA homopolymer using the same technique indicated a mean degree of polymerization (DP) of 34 (Figure S1).…”

“…Moreover, comparing the C 1s XPS data obtained for the PGEO5MA and PAGEO5MA brushes revealed a shift in the ratio of the O−C�O, C�O, C−O−C/C−O−H, and C−H peaks that is consistent with brush oxidation (Figure S14). 36 Recently, we have reported that PAGEO5MA-based chains, 32 diblock copolymer nano-objects, 33,35 and brushes 36 can be further functionalized with various amino acids, such as L-histidine, via reductive amination. For surface-grafted PAGEO5MA brushes, this involves immersion into an aqueous solution containing the desired amine reagent and sodium cyanoborohydride (NaBH 3 CN), prior to heating to 50 °C for 24 h. Herein, this protocol was adapted to functionalize PAGEO5MA brushes using a hydrophilic diamine (Jeffamine EDR-148) to prepare the corresponding PDAGEO5MA brushes, as illustrated in Scheme 2.…”

“…Recently, we reported that the pendent cis -diol functionality on PGEO5MA homopolymers, PGEO5MA-based diblock copolymer nano-objects, and PGEO5MA brushes can be selectively oxidized using sodium periodate (NaIO 4 ) under mild reaction conditions to form the respective aldehyde-functional PAGEO5MA-based materials. The resulting PAGEO5MA chains can be further functionalized using various primary amines (including amino acids) via reductive amination. ,,, In the present study, our aim was to extend these reports by investigating whether dynamic imine bond formation could be used to promote the chemical adsorption of PAGEO5MA-stabilized diblock copolymer spheres of varying size onto surface-grafted amine-functionalized PDAGEO5MA brushes to produce a library of model soft hybrid surfaces of tuneable topography for friction coefficient measurements.…”

“… Selective oxidation of the pendent cis -diol groups was confirmed by both ellipsometry and X-ray photoelectron spectroscopy (XPS) studies. Periodate oxidation should lead to a reduction in the molecular weight of each repeat unit owing to the loss of a formaldehyde molecule . Thus, given that the dry brush thickness is proportional to the polymer molecular weight, complete oxidation of the PGEO5MA repeat units is expected to produce an approximate 8.5% reduction in dry thickness .…”

“…Recently, we reported a new hydrophilic aldehyde-functional polymer (PAGEO5MA). − This polymer can either be directly synthesized from the corresponding methacrylic monomer (AGEO5MA) or it can be generated via selective oxidation of a cis -diol-functional PGEO5MA precursor using sodium periodate (NaIO 4 ) . PAGEO5MA-based diblock copolymer spheres or vesicles can be reacted with various amino acids (e.g., glycine or l -histidine) via Schiff base chemistry followed by reductive amination. , PAGEO5MA-based diblock copolymer worms form soft, free-standing gels that exhibit strong mucoadhesion, while PAGEO5MA brushes grafted from a planar surface can be reacted with model globular proteins, such as bovine serum albumin (BSA) .…”