Composite microgel containing

Figure 8.9 Confocal fluorescence microscopy image of a composite microgel containing both hydrophobic dye Nile Red (compartmentalized in hexadecane nanodroplets) and hydrophilic dye 4, 6-diamidino-2-phenylindole (DAPI) (compartmentalized in poly(N-isopropylacrylamide)). The images were acquired by exciting Nile Red...

Dalmont, H., Pinprayoon, O., and Saunders, B. 2008. Study of pH-responsive microgels containing methacrylic acid Effects of particle composition and added calcium. Langmuir 24 2834-2840. 

The temperature dependence of the Payne effect has been studied by Payne and other authors [28, 32, 47]. With increasing temperature an Arrhe-nius-like drop of the moduli is found if the deformation amplitude is kept constant. Beside this effect, the impact of filler surface characteristics in the non-linear dynamic properties of filler reinforced rubbers has been discussed in a review of Wang [47], where basic theoretical interpretations and modeling is presented. The Payne effect has also been investigated in composites containing polymeric model fillers, like microgels of different particle size and surface chemistry, which could provide some more insight into the fundamental mechanisms of rubber reinforcement by colloidal fillers [48, 49]. 

Rubio Retama, J., E. Lopez Cabarcos, D. Mecerreyes, and B. L opez-Ruiz. 2004. Design of an amperometric biosensor using polypyrrole-microgel composites containing glucose oxidase. Biosens Bioelectron 20 1111. 

We were concerned that this apparent shear-thinning behavior in our short cores might be an experimental artifact (associated with microgels or very-high-MW polymer species) that could not be expected to propagate far into a real reservoir. To test this idea, we performed an experiment in a 57-md Berea sandstone core that was 122 cm long, with four equally spaced internal pressure taps, which created five 24.4-cm sections within the core. The core porosity was 17.3%, and the core cross section was 15.24 cm. The permeabilities of the five core sections were 53, 64, 65, 74, and 41 md, respectively, giving a composite permeability of 57 md. The core was saturated with filtered 2.52%-TDS brine (2.3% NaCl -H 0.22% NaHCOj), and our polymer solution contained 600-ppm CP Kelco xanthan in this same brine. 

FIGURE 16.1 Principal structural types of micro- and nanogels (a) Cross-linked networks, (b) networks associated with hydrophobic domains (e.g., cholesterol molecules), (c) core-shell structure of two different networks, (d) multilayer networks (microgel covered with two polyelectrolyte layers is shown), (e) composite solid core-soft shell networks containing metal, ceramic, or protein NPs, (f) composite raisin-in-pie type of microgel with metal NPs dispersed in the network. 

The relative content of polymers was varied to determine the effect of overall microgel composition on mechanical behavior. While all three (sodium alginate, NIPAm, and cross-linker (N,N -methylenebis(acrylamide) (BIS))) were varied, only the effects of soditrm alginate variation will be discussed here. The compositions studied are outlined in Table 1 with set B, D, and E containing the alginate variations. 

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