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pH and Generation Dependent Morphologies of PAMAM Dendrimers on Graphene Substrate


The adsorption of PAMAM dendrimers at solid/water interfaces is extensively studied, which is majorly driven by electrostatic and van der Waals interactions between the substrate and the dendrimers. However, the pH dependence on the adsorption driven predominantly by van der Waals interactions is poorly explored, which is crucial for investigating the potentiality of these dendrimers in supercapacitors, surface patterning. Motivated by this aspect, we have studied the adsorption behavior of PAMAM dendrimers of generations 2 (G2) to 5 (G5) with pH and salt concentration variation, on a charge neutral graphene substrate, using fully atomistic molecular dynamics simulations. The instantaneous snapshots from our simulations illustrate that the dendrimers deform significantly from their bulk structures. Based on various structural property calculations, we classify the adsorbed dendrimer morphologies into five categories and map them to a phase diagram. Interestingly, the morphologies we report here have strikingly analogies with those reported in star-polymer adsorption studies. From the fractional contacts and other structural property analyses we find that the deformation is more pronounced at neutral pH compared to high and low pH. Higher generation dendrimers resist deformation following the trend, G2 > G3 > G4 > G5 at any given pH level. As the adsorption here is majorly driven by van der Waals interactions, we observe no desorption of the dendrimers as the salt molarity is increased, unlike as reported in the electrostatically driven adsorption studies.

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Publication details

The article was received on 25 Jan 2018, accepted on 15 Feb 2018 and first published on 15 Feb 2018

Article type: Paper
DOI: 10.1039/C8SM00179K
Citation: Soft Matter, 2018, Accepted Manuscript
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    pH and Generation Dependent Morphologies of PAMAM Dendrimers on Graphene Substrate

    M. Gosika and P. K. Maiti, Soft Matter, 2018, Accepted Manuscript , DOI: 10.1039/C8SM00179K

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