All of them as it's the van der Waals attraction combined with solid-solid diffusion that ensures that particles < 100 nm or higher, in a powder or dried, combine to form a mass of fused sub- and post-micron aggregates and agglomerates. This will occur at room temperature.

Heat drying of colloidal NPs increase the aggregation and lead to the formation of larger flocs. I would suggest you to eliminate the heat drying as it might lead to degradation of reactants and opt for better methods if available. Whereas, freeze-drying with suitable cryoprotectant seems to be the better option which gives high yield, even for smaller samples.

Anupma Thakur Even freeze-drying will generate aggregates.... See (open the first in Internet Explorer; not enabled for mobile viewing):

Dispersion and nanotechnology http://tinyurl.com/hpywsge

Adhesion and cohesion http://tinyurl.com/zwb2wlh

Hi

Heat drying of colloidal nanoparticles enhance the aggregation rate compared to freeze-drying.

@Alan F Rawle, thank you for Sir for adding up knowledge to this.

Alan F Rawle

thanks for the presentations you shared but unfortunately the first 1 doesn't open on any browser

R. Atchudan Anupma Thakur

thanks for your reply, could you please show any evidence on that like a paper or a book includes a comparison .. thanks

Hussein S. Moghaieb I've just opened the first presentation with Internet Explorer 11 - it works well on this old format. Some of our older talks are being reformatted for mobile use and this will allow more browsers.

Alan F Rawle I've tried with IE11 but doesn't work as well, any possibility to upload the file itself or if you send me on [email protected] if you don't mind : ) .. thanks

Hussein S. Moghaieb You may have Flash player issues that could be part of your internal IT policy. The material is virtually useless without the talk to accompany it. I'm working with our IT department to make some of these earlier webinars accessible to Chrome and Firefox.

Dear Hussein S. Moghaieb,

Kindly find the attachment which will be helpful for your question.

hi

heat drying of colloidal nanoparticles, will increases the aggregation/agglomeration more.