Tuning the softness of poly(2-hydroxyethyl methacrylate) nanocomposite hydrogels through the addition of PEG coated nanoparticles

Leandro Toledo; Daniel A Palacio; Bruno F Urbano

doi:10.1016/j.jcis.2020.06.043

Tuning the softness of poly(2-hydroxyethyl methacrylate) nanocomposite hydrogels through the addition of PEG coated nanoparticles

J Colloid Interface Sci. 2020 Oct 15:578:749-757. doi: 10.1016/j.jcis.2020.06.043. Epub 2020 Jun 12.

Authors

Leandro Toledo¹, Daniel A Palacio¹, Bruno F Urbano²

Affiliations

¹ Departmento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile.
² Departmento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile. Electronic address: burbano@udec.cl.

PMID: 32570144
DOI: 10.1016/j.jcis.2020.06.043

Abstract

Hypothesis: In nanocomposites, several factors govern the enhancement of properties when a nanofiller is added into a polymer matrix. Previously, our group have demonstrated that stabilizing nanoparticles improves the dispersion of nanoparticles in a hydrogel, but their effect on viscoelastic properties remain unclear. We hypothesized that coating the nanoparticles will block matrix-nanoparticle interactions, which would then affect the transfer of stress when the hydrogel is subjected to stress.

Experiment: To this end, we investigated the effects that nanofillers coated with polyethylene glycol (PEG) of variable molar mass have on the properties of physical hydrogels made from poly(2-hydroxyethyl methacrylate). PEG with molar masses of 6, 20, and 35 kDa were used at different concentrations and the viscoelastic properties of the resulting hydrogels were studied and compared with control hydrogels with and without nanofillers.

Findings: The coated nanofiller resulted in enhanced dispersion stabilization as the molar mass and concentration of the PEG increased. However, there were noticeable changes in viscoelastic properties. In general, the nanocomposite hydrogels exhibited reduced shear modulus, greater creep, and more accentuated shear thinning behaviour. These effects were attributed to hindered matrix-nanoparticle interactions because of the PEG coating, an increased slippage of the PHEMA chains as well as a plasticizing effect.

Keywords: Coated nanoparticles; Nanocomposite hydrogels; Shear thinning; Viscoelasticity.