Molecular dynamics insight into viscosity reduction of hydrolysed polyacrylamide by using carbon quantum dots

Guice Yao; Jin Zhao; Maje Alhaji Haruna; Dongsheng Wen

doi:10.1039/d1ra03935k

Molecular dynamics insight into viscosity reduction of hydrolysed polyacrylamide by using carbon quantum dots

RSC Adv. 2021 Jul 28;11(42):26037-26048. doi: 10.1039/d1ra03935k. eCollection 2021.

Authors

Guice Yao¹, Jin Zhao², Maje Alhaji Haruna³, Dongsheng Wen^{1

2

3}

Affiliations

¹ School of Aeronautic Science and Engineering, Beihang University Beijing 100191 China.
² School of General Engineering, Beihang University Beijing 100191 China Jin.Zhao@buaa.edu.cn d.wen@buaa.edu.cn.
³ School of Chemical and Process Engineering, University of Leeds Leeds LS2 9JT UK d.wen@leeds.ac.uk.

Abstract

Hydrolysed polyacrylamide (HPAM) is widely used in many industrial fields where its rheological properties play a leading role. Recent discovery of the reduction of HPAM's viscosity by adding carbon quantum dots (CQDs), however, is controversial to the established theories. By using all atom molecular dynamics simulation with an OPLS-AA force field, this study aims to provide detailed molecular insight into such an uncommon phenomenon. The dynamic structures of the HPAM chain in the presence or absence of CQDs were clearly captured from the molecular aspect. The results reveal that the adsorption of CQD reduces the gyration radius of the HPAM chain, and it is the corresponding hydration effect that leads to the reduction of the viscosity. The amide rather than the carboxylate group along the HPAM chain is dominant in terms of the interaction with the CQDs, and the driven atoms depend on the surface where the polymer is adsorbed.