Thermoresponsive hydrogels have emerged as a cornerstone in smart material design due to their ability to undergo reversible structural changes in response to temperature variations. This study presents the development of hetero-network hybrid hydrogels by crosslinking two distinct thermoresponsive copolymers—poly(N-isopropyl acrylamide-co-3-methacryloxypropyl trimethoxysilane) (pNS) and poly(N-(3-methoxy propyl)acrylamide-co-3-methacryloxypropyl trimethoxysilane) (pMS)—using colloidal silica nanoparticles as multifunctional crosslinkers. The pNS copolymer exhibits a lower critical solution temperature (LCST) of approximately 33 °C, while pMS displays an LCST around 73 °C, enabling dual-phase thermal responsiveness within a single hydrogel system. These reactive copolymers were synthesized via free radical polymerization using 3-methacryloxypropyl trimethoxysilane (S) as a functional monomer with reactive silane side chains, allowing for covalent integration with silica nanoparticles during gelation.
The hydrogels were prepared by mixing aqueous solutions of pNS and pMS with a silica nanoparticle suspension (average diameter: 12 nm), followed by rapid vortex mixing and ambient aging at 25 °C. The resulting materials exhibited high transparency across all composition ratios tested (2–5 wt%), indicating excellent miscibility and homogeneous network formation. Fourier-transform infrared (FTIR) spectroscopy confirmed the presence of Si–O–C bonds formed through condensation reactions between methoxysilyl groups on the copolymers and surface silanol groups on silica nanoparticles. ¹H NMR analysis further verified the incorporation of both monomers into the copolymer chains, with quantitative ratios derived from peak intensities.
Differential scanning calorimetry (DSC) revealed two distinct endothermic transitions corresponding to the LCSTs of pNS (~33 °C) and pMS (~73 °C), confirming that each network undergoes independent phase transitions without significant interference. UV-Vis spectrophotometric measurements demonstrated reversible turbidity changes at these temperatures, with transmittance dropping sharply above each LCST. Notably, the pNS(2)–pMS(3)–Si(5) hydrogel exhibited a two-step deswelling behavior: first shrinking at ~33 °C due to pNS collapse, then a second contraction at ~73 °C linked to pMS transition, enabling precise control over water release dynamics.
Swelling experiments showed equilibrium swelling ratios of 44, 48, and 53 g·g⁻¹ for pMS(5)–Si(5), pNS(5)–Si(5), and the hetero-network hydrogel, respectively. The enhanced swelling capacity in the hetero-network was attributed to the hydrophilic nature of pMS and its contribution to increased network porosity.CD90 Antibody site Rheological studies indicated that storage modulus (G′) significantly increased near each LCST, reflecting structural stiffening upon dehydration.315-22-0 manufacturer Importantly, the hetero-network hydrogel maintained uniform shrinkage without cracking or deformation, preserving shape integrity—a key advantage for biomedical applications.PMID:34585414
This work demonstrates a facile, scalable strategy to engineer multi-responsive hydrogels with independently tunable thermal behaviors. By adjusting the relative amounts of pNS, pMS, and silica nanoparticles, one can precisely modulate the onset temperature, degree of deswelling, and release kinetics. The absence of unreacted monomers, high transparency, and robust mechanical performance make these hetero-network hydrogels highly promising for advanced drug delivery systems, tissue engineering scaffolds, and responsive actuators. Future exploration could extend this platform to other stimuli-responsive polymers, enabling multi-stimuli responsive hybrid materials with programmable functions.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
