Supporting Information 1. Mechanism of Friedel-Crafts alkylation1 (a) Initiation: aluminum chloride reacts with impurities like water to form a complex, which reacts further with unsaturated compounds (styrene in our work) forming the initial carbocation. AlCl3 H 2 O AlCl3OH H (AlCl3OH) H R CH = CH 2 (R C H CH 3 ) (AlCl3OH) (b) Chain scission of POE: the initial carbocation attacks POE, forming a moacrocarbocation, PE+, which undergoes a chain scission through electron rearrangement. The short branch of POE is not drawn. R CH 2 CH 2 CH 2 CH 2 RH + CH 2 CH 2 C H CH 2 CH 2 CH 2 C H CH 2 C H 2 + H 2C = CH CH 2 (c) Grafting: the fragments of POE chain can substitute for a proton from the benzene ring of PS, forming a POE-g-PS copolymer. AlCl3 R CH CH 2 PS POE-g -PS AlCl3X R C H 2 PS POE-g -PS 2. Comparisons between model fittings and experiments Figure S1. Storage modulus, loss modulus and complex viscosity of PS/POE 20/80 physical blend (a) and 50/50 physical blend (b) at 180oC. The solid lines in (a) denote the fit of Palierne model with Rv=0.37µm and =1mN/m. The solid lines in (b) denote the fit of YZZ model with lc=4.82µm and=1mN/m. Figure S2. Storage modulus, loss modulus and complex viscosity of PS/POE 20/80 reactive blend (a) and 50/50 reactive blend (b) at 180oC. The solid lines in (a) denote the prediction of Palierne model with Rv=0.20µm and =0=1mN/m and the additional contributions from micelles is calculated by Yu-Zhou model. The solid lines in (b) denote the prediction of YZZ model with lc=0.67µm and =0=1mN/m and the additional contributions from micelles is calculated by Yu-Zhou model. The micelles are assumed to be “unswollen” and m=0.20=0.2mN/m. The radius of unswollen micelle particles is taken as 20nm. Figure S3. Storage modulus, loss modulus and complex viscosity of PS/POE 20/80 reactive blend (a) and 50/50 reactive blend (b) at 180oC. The solid lines in (a) denote the prediction of Palierne model with Rv=0.20µm and =0=1mN/m and the additional contributions from micelles is calculated by Yu-Zhou model. The solid lines in (b) denote the prediction of YZZ model with lc=0.67µm and =0=1mN/m and the additional contributions from micelles is calculated by Yu-Zhou model. The micelles are assumed to be swollen and m=0.20=0.2mN/m. The radius of swollen micelle particles is taken as 30nm. 3. Fitting by anisotropic Palierne model The loss modulus and complex viscosity of reactive blends are shown in Fig. S4. The dynamic moduli of 20/80 physical blend and reactive blend were fitted using Palierne model2, which is expressed as Gb* Gm* 1 3 H 1 2 H (S1) H 4 RV 2Gm* 5Gd* Gd* Gm* 16Gm* 19Gd* E 40 RV Gm* Gd* 2Gd* 3Gm* 16Gm* 19Gd* D (S2) E RV 23Gd* 16Gm* 2 24 2 16 RV RV2 D RV 13Gd* 8Gm* 2 4 23Gd* 32Gm* 13Gd* 12Gm* RV RV 48 2 32 RV RV2 (S3) (S4) where is the volume fraction of droplets, is the interfacial tension, Rv is the volume average radius and is the angular frequency. Gm* , Gd* and Gb* are complex modulus of matrix, droplet and blend, respectively. and are interfacial dilatation modulus and interfacial shear modulus, respectively. In the case of physical blend, and are zero, which corresponds to isotropic version of Palierne model. In reactive blend, when copolymers stay at the interface, it is usually assumed that they can induce additional interfacial viscosity. and are often assumed to obey Maxwell equation '(") 10 20 iif 1 2 1 iif 1 2 (S5) In the fitting, is taken as zero and if 2 is assumed to be infinity, which results in 20 . Both the fitting results using isotropic Palierne model (Eq. S1-S2 with E D 0 ) and anisotropic Palierne model (Eq. S1-S5 with non-zero 20 ) for 20/80 physical blend and reactive blend are shown in Fig. S5. As shown in Fig. S5b, considering interfacial elasticity in Palierne model only slightly increases G’ at low frequency, which are still much smaller than experimental data. Figure S4. The loss modulus (a) and complex viscosity (b) of reactive blends. Figure S5. Fitting of the dynamic moduli of PS/POE 20/80 physical blend (a) and reactive blend (b) using Palierne model. The solid lines are fitting results using isotropic Palierne model with Rv=0.20µm and =1mN/m. The dash line in (b) is the fitting result using anisotropic Palierne model with 2=0.001mN/m. Reference 1. Sun YJ, Baker WE. Polyolefin/Polystyrene In situ compatibilization using Friedel– Crafts alkylation. J. Appl. Polym. Sci. 1997; 65: 1385-1393 2. Jacobs U, Fahrländer M, Winterhalter J, Friedrich C. Analysis of Palierne’s emulsion model in the case of viscoelastic interfacial properties. J. Rheol. 1999; 43: 14951509