Temperature and pH responsive hydrogels based on polyethylene glycol analogues and poly(methacrylic acid) via click chemistry

Abstract

A novel temperature responsive copolymer, poly[2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene glycol) methacrylate-co-N-hydroxymethyl acrylamide] [P(MEO 2 MA-co-OEGMA-co-HMAM)], was synthesized by atom transfer radical polymerization. pH responsive poly(methacrylic acid) (PMAA) was synthesized by reversible addition-fragmentation chain transfer polymerization. After the hydroxyl groups on P(MEO 2 MA-co-OEGMA-co-HMAM) were transformed into azide groups and the carboxyl groups on PMAA were transformed into alkyne groups respectively, a novel temperature and pH responsive hydrogel was fabricated by click chemistry between the azide-P(MEO 2 MA-co-OEGMA-co-HMAM) and alkyne-PMAA in the presence of CuSO 4 and sodium ascorbate in aqueous solution. The rheological kinetics of gel formation demonstrated that gelation had commenced within 5 min at 25 ∘ C, since then the storage modulus (G ′ ) was higher than the loss modulus (G ′′ ). SEM images of hydrogel morphology and the swelling ratios of hydrogel at different temperatures and pH proved that the formed hydrogel had temperature and pH sensitivities. Bovine serum albumin was used as a model to evaluate the sustained release of the hydrogel; the results indicated that the hydrogel was a promising candidate for controlling protein drug delivery.

Synthesis of Thermo-Responsive Block-Graft Copolymer Based on PCL and PEG Analogs, and Preparation of Hydrogel via Click Chemistry

“…The reason for this is that the hydrophobic interactions of PCL–PEG chains at a higher temperature ( T > LCST). The SEM images of the hydrogels at different temperature certified that two gels are temperature-sensitive [44].…”

Thermoresponsive Nanogels Based on Different Polymeric Moieties for Biomedical Applications

“…OEGMA-based thermoresponsive materials are widely used as drug carrier hydrogels and nanogels [ 161 , 162 ]. Cortes et al prepared a thermosensitive and magnetic-responsive nanogel for intracellular remote release of DOX.…”

Stereocomplex Poly(Lactic Acid) Amphiphilic Conetwork Gel with Temperature and pH Dual Sensitivity

“…However, the gel has tight structure and small pore size at pH 9 and 25 • C. This is because at higher pH values (pH > pKa), DEAEMA units are deprotonated and the formation of hydrogen bonds inside the gel plays a major role. Resulting in polymer chains PDEAEMA shrink and network structure of the gel is tight [1,44,45]. Figure 9 are digital photos of gel2 at different environments.…”