**1. Introduction**

It is now acknowledged that non-Newtonian fluids in industrial, physiological and technological processes are more significant than viscous fluids. Few examples of such fluids may include silicon oils, printer ink, mud, ice cream, egg yolk, blood at low shear rate, shampoo, gypsum paste, polymer solutions, nail polish, sand in water, ketchup etc. Rheological properties of such fluids are different and thus all these cannot be explained employing one constitutive relationship between shear rate and rate of strain. The modelled expressions for the non-Newtonian liquids are more tedious and of higher order than Navier–Stokes expressions for viscous fluids. Researchers in the field face challenges in modelling, analysis and computations from different quarters. Through different non-Newtonian fluids, the objective here is to explore second grade and elastico-viscous fluids [1–8].

Nanofluids are described by carbon nanotubes (CNTs) [9–11], Buongiorno [12] and Tiwari and Das [13] models. Therefore, the information is very significant about flows involving thermophoresis aspects. Impact of slip in flow of copper-water nanoliquid over an extendable surface is examined by Pandey and Kumar [14]. Flow of couple stress nanomaterial bound by an oscillatory stretchable surface is analyzed by Khan et al. [15]. Turkyilmazoglu [16] discussed free and circular jets in view of single phase nanomaterial. Few relevant investigatons for nanoliquids can be seen in studies [17–45].

According to previous literature, it is found that magnetohydrodynamic stretched flow of viscoelastic nanofluids with heterogeneous–homogeneous reactions has not been reported yet. Attention in modeling has been specially focused on constitutive relations of viscoelastic fluids. Heat and mass transport process is explored by thermophoresis and Brownian dispersion. Adequate transformations are considered to dimensionless the governing system. Numerical solutions of the resulting system are obtained by employing the shooting method. Contributions of numerous sundary variables on flow fields are interpreted through plots and numerical data.
