Microstructure of colloid-polymer mixtures containing charged colloidal disks and weakly-adsorbing polymers

POLYMER

卷:105

Article

Kishore, Suhasini^1,2  Srivastava, Sunita^2,3  Bhatia, Surita R.² 

[1] Univ Massachusetts Amherst, Dept Chem Engn, Amherst, MA 01003 USA

[2] SUNY Stony Brook, Dept Chem, Stony Brook, NY 11794 USA

[3] NIST, Gaithersburg, MD 20899 USA

关键词: Nanoparticle;    USAXS;    Clay;   

DOI  :  10.1016/j.polymer.2016.07.091

来源: Elsevier

【 摘 要 】

Structural arrest in an aging colloid-polymer mixture of charged colloidal disks and weakly interacting polymers is primarily governed by the spatial arrangement of microstructural domains in the system. Here we present a detailed ultra-small angle x-ray scattering (USAXS) study of the polymer induced microstructural changes occurring in systems containing laponite (R) and poly(ethylene oxide) (PEO). Laponite (R) suspensions are known to transition from a homogeneous fluid to an arrested phase as a function of time. USAXS results show that when polymer chains are added to this colloidal system, the microstructural changes are found to depend on (i) polymer-colloid size ratio, (ii) particle and polymer concentration. Large length scale structures (300-1000 nm) of non-uniformly varying size appear with increasing concentration of high molecular weight PEO (R-g/R similar to 2.4). However with shorter PEO chains (R-g/R similar to 0.5), we observe the formation of intermediary structures with a characteristic length scale of 50 -60 nm. With increasing particle concentration, we observe a more compact structure for the high molecular weight PEO and no signature of a percolating network in the case of the low molecular PEO. We believe that these results add to our understanding of the complex aging behavior of clay-polymer systems. (C) 2016 Elsevier Ltd. All rights reserved.

【 授权许可】

Free