We built advanced materials from colloids

 

We use colloidal particles as building blocks for advanced supracolloidal materials. Our portfolio contains the development of waterborne coatings that have resistance to organic solvents, gas sensors, armored colloidal systems for delivery of drugs or benificial agents, and polymer particles modified hybrid biological plant spores

 

 
The vast majority of reports on Janus particles deal with the fabrication and behavior of anisotropic particles that have both lyophilic and lyophobic features. Opposing characteristics on a single particle, however, can span a wide variety of physical properties. We have fabricated dumbbell or peanut-shaped microparticles that have one hard polystyrene lobe, and one soft lobe made from poly( n -butyl acrylate). A mechanistic study on their synthesis we have reported in the ACS Journal  Langmuir  in  2014  entitled  Synthesis of "hard-soft" Janus particles by seeded dispersion polymerization  (you can read the paper here:    http://dx.doi.org/    10.1021/la503366h ). We found in a study reported in  2014  in  Soft Matter  that these "hard-soft" Janus particles upon collision under sheared and dilute condition, whereby physisorbed poly(vinyl pyrrolidone) which served as steric stabilizer desorbed from the particles rendering them colloidally unstable, these could assemble into   distinct microscopic supracolloidal analogues of simple molecular valance shell electron pair repulsion (VSEPR) space-fill structures.   Simulations of expected cluster morphology, compared with those from cryo-SEM analysis support the mechanism of assembly driven by surface area minimization in the case of soft–soft interactions. Altering the soft lobe size with respect to the hard lobe indicates a moderate effect on number of primary particles per cluster. Additionally, higher order structures of clusters containing a number of primary particles exceeding what is possible for a ‘solid’ core cluster are observed. As such, we also investigated the formation of suprastructures using a high number of ‘hard–soft’ Janus particles and verified their effective Pickering stabilization of air bubbles. You can read the paper here:  http://dx.doi.org/    10.1039/C4SM01708K .  

The vast majority of reports on Janus particles deal with the fabrication and behavior of anisotropic particles that have both lyophilic and lyophobic features. Opposing characteristics on a single particle, however, can span a wide variety of physical properties. We have fabricated dumbbell or peanut-shaped microparticles that have one hard polystyrene lobe, and one soft lobe made from poly(n-butyl acrylate). A mechanistic study on their synthesis we have reported in the ACS Journal Langmuir in 2014 entitled Synthesis of "hard-soft" Janus particles by seeded dispersion polymerization (you can read the paper here:  http://dx.doi.org/10.1021/la503366h). We found in a study reported in 2014 in Soft Matter that these "hard-soft" Janus particles upon collision under sheared and dilute condition, whereby physisorbed poly(vinyl pyrrolidone) which served as steric stabilizer desorbed from the particles rendering them colloidally unstable, these could assemble into distinct microscopic supracolloidal analogues of simple molecular valance shell electron pair repulsion (VSEPR) space-fill structures. Simulations of expected cluster morphology, compared with those from cryo-SEM analysis support the mechanism of assembly driven by surface area minimization in the case of soft–soft interactions. Altering the soft lobe size with respect to the hard lobe indicates a moderate effect on number of primary particles per cluster. Additionally, higher order structures of clusters containing a number of primary particles exceeding what is possible for a ‘solid’ core cluster are observed. As such, we also investigated the formation of suprastructures using a high number of ‘hard–soft’ Janus particles and verified their effective Pickering stabilization of air bubbles. You can read the paper here: http://dx.doi.org/10.1039/C4SM01708K.  

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