Dear Nazan Gökşen Tosun, first the word hybrid doesn't fit here, since all components are organic polymers. Since you have an agregation/precipitation, most likely PVA is not doing its job. This is either because the MW is not the appropriate one or for such binary polymers system PVA itself is not the best choice of stabilizer. Are you following any previous work ? My Regards

6000 seems a little low for a steric stabilizer, especially PVA which more closely resembles a homopolymer than a block copolymer. Try a higher MW or a PVA with a different degree of hydrolysis.

Dear all, please refer to the following chapter which explains the floculation mechanisms behind the instability (coalescence, agregation and precipitation) of PVA. As a summery, two of the most famous floculation mechanisms are operation with respect to MW. Low MWs PVA provoke instability via surface charge neutralization floculation, and on the other hand high MWs PVA provoke floculation by interparticles bridging. The values of high and low MWs are speified in the chapter. My Regards

Chapter 14: Flocculation of sterically stabilized dispersions.

https://doi.org/10.1515/9783110540895-015

In:

Handbook of Colloid and Interface Science_Vol.01 - Basic Principles of Interface Science and Colloid Stability

Tharwat F. Tadros (2018 edt)

Amazing what decent textbooks on the *basic principles* of colloid science can reveal, isn't it?!?

It's a sad fact of modern life that people try to make colloids without understanding the basic concepts. I blame the "nano" cash chasers for that.

Nazan Gökşen Tosun some remarks

PVA is not a surfactant, it acts as a (de)stabilizer. You may try typical surfactants used for stabilization of PEI dispersions. Maybe in the acidic pH-range the PEI part already will be a perfect stabilizer.

If you give particle size you should also give the method. Likely, it makes no sense to give the particle size with one digit. I am skeptical, that you have this precision.

J Phys Chem C Nanomater Interfaces. Author manuscript; available in PMC 2019 Dec 16.

Published in final edited form as:

Published online 2019 May 24. doi: 10.1021/acs.jpcc.9b00913J Phys Chem C Nanomater Interfaces. 2019 Jul 11; 123(27): 16495–16507.

PMCID: PMC6913534

NIHMSID: NIHMS1032294

PMID: 31844485

What Does Nanoparticle Stability Mean?

Hoa T. Phan and Amanda J. Haes*

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Abstract

The term “nanoparticle stability” is widely used to describe the preservation of a particular nanostructure property ranging from aggregation, composition, crystallinity, shape, size, and surface chemistry. As a result, this catch-all term has various meanings, which depend on the specific nanoparticle property of interest and/or application. In this feature article, we provide an answer to the question, “What does nanoparticle stability mean?”. Broadly speaking, the definition of nanoparticle stability depends on the targeted size dependent property that is exploited and can only exist for a finite period of time given all nanostructures are inherently thermodynamically and energetically unfavorable relative to bulk states. To answer this question specifically, however, the relationship between nanoparticle stability and the physical/chemical properties of metal/metal oxide nanoparticles are discussed. Specific definitions are explored in terms of aggregation state, core composition, shape, size, and surface chemistry. Next, mechanisms of promoting nanoparticle stability are defined and related to these same nanoparticle properties. Metrics involving both kinetics and thermodynamics are considered. Methods that provide quantitative metrics for measuring and modeling nanoparticle stability in terms of core composition, shape, size, and surface chemistry are outlined. The stability of solution-phase nanoparticles are also impacted by aggregation state. Thus, collision and DLVO theories are discussed. Finally, challenges and opportunities in understanding what nanoparticle stability means are addressed to facilitate further studies with this important class of materials.

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Graphical Abstract

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