Polyacryloyl Hydrazide: An Efficient, Simple, and Cost Effective Precursor to a Range of Functional Materials through Hydrazide Based Click Reactions

Abstract

Preparation and studies of ion exchangeable epoxy resins, stimuli responsive hydrogels, and polymer-dye conjugates have been accomplished through hydrazide based click reactions using polyacryloyl hydrazide (PAH) as the precursor. A convenient synthesis of PAH with quantitative functionality was achieved by treatment of polymethyl acrylate with hydrazine hydrate in the presence of tetra-n-butyl ammonium bromide. PAH was cured with bisphenol A diglycidyl ether (BADGE) at 60 °C to form transparent resins with superior mechanical properties (tensile strength = 2-40 MPa, Young's modulus = 3.3-1043 MPa, and ultimate elongation = 9-75%) compared to the conventional resins prepared using triethylene tetramine. The resins exhibited higher ion exchange capacities (1.2-6.3 mmol/g) compared to the commercial AHA ammonium-type (Tokuyama Co., Japan) membranes. An azo dye with aldehyde functionality was covalently attached to PAH through hydrazone linkage, and the dye labeled PAH exhibited colorimetric sensing ability for base and acids up to micromolar concentration. The swelling of the PAH based hydrogel varied in the range 4-450% depending on the pH and temperature of the medium. The hydrogels gradually released 30% of the original encapsulated dye in a period of 200 h. PAH-hydroxy naphthaldehyde conjugate released 75% of the original loading in ∼11 days at 37 °C and pH 5.0 through cleavage of the -CONHN═C- linkage. The study depicts the versatility of PAH as a precursor and inspires synthesis of a range of new materials based on PAH in the future.

General Reagent Free Route to pH Responsive Polyacryloyl Hydrazide Capped Metal Nanogels for Synergistic Anticancer Therapeutics

“…29 The synthetic procedure for PAH-Ag NPs followed by hydrogel formation is illustrated in Scheme 1. The PAH-Ag NPs were synthesized by adding different concentrations (0.2−4.0 mmol/L) of AgNO 3 to 0.02 g/mL aqueous solution of PAH (pH ≈ 8.7) at room temperature.…”

“…28 Recently, we have proposed a simple and cost-effective procedure to synthesize PAH possessing hydrazide functionality in each repeating unit. 29 The motive behind selecting PAH for the synthesis of metal NPs is multifold. PAH would serve as the reducing agent for the metal ion precursors.…”

In Situ Functionalized Polymers for siRNA Delivery

“…Accordingly, hydrazone formation has been widely used in biological settings including drug delivery, sensing, or even in the synthesis of polynucleotide delivery vectors . However, the use of poly(hydrazide) as a “clickable” and versatile scaffold has been limited and only a few examples report its use to synthesize glycopolymers or for pH‐responsive drug delivery . Alternative elegant strategies for multi‐hydrazone formation have also been developed in the context of DNA or protein‐templated dynamic combinatorial libraries …”

In Situ Functionalized Polymers for siRNA Delivery

“…Zuschriften responsive drug delivery. [16,23,24] Alternative elegant strategies for multi-hydrazone formation have also been developed in the context of DNAorprotein-templated dynamic combinatorial libraries. [25][26][27][28] Thep roposed poly(acryloyl hydrazide) scaffold (P1)w as prepared using controlled free radical polymerization (see the Supporting Information).…”