Michel Bouquey

Co-axial capillaries microfluidic device for synthesizing size- and morphology-controlled polymer core-polymer shell particles

An easy assembling-disassembling co-axial capillaries microfluidic device was built up for the production of double droplets. Uniform polymer core-polymer shell particles were synthesized by polymerizing the two immiscible monomer phases composing the double droplet. Thus poly(acrylamide) core-poly(tri(propylene glycol) diacrylate) shell particles with controlled core diameter and shell thickness were simply obtained by adjusting operating parameters. An empirical law was extracted from experiments to predict core and shell sizes. Additionally uniform and predictable non-spherical polymer objects were also prepared without adding shape-formation procedures in the experimental device. An empirical equation for describing the lengths of rod-like polymer particles is also presented.

Multiscale materials from microcontinuous-flow synthesis: ZnO and Au nanoparticle-filled uniform and homogeneous polymer microbeads

Tri(propylene glycol) diacrylate (TPGDA) was found to be an excellent monomer for the stabilization and dispersion of inorganic nanoparticles. Uniform nano-Au/poly(TPGDA) and nano-ZnO/poly(TPGDA) composite microbeads were synthesized in situ using a designed axisymmetric capillary-based flow-focusing microfluidic device without any additional surfactant or coupling agent. Using the designed mixing-enhanced microfluidic device, homogeneous nano-inorganic/polymer composites with a high content of nanoparticles were obtained. Morphologies of the composites were characterized by SEM, TEM, surface microscopy, dark-field microscopy and internal fluorescence.

Dynamic Compressive Behavior of a Melt Mixed Polypropylene/Organoclay Nanocomposites

This work aims to investigate the dynamic behavior of polypropylene organoclay nanocomposites. The nanocomposite was obtained by mixing the polypropylene matrix with a masterbatch of polypropylene modified anhydride maleic and montmorillonite organoclay (pp-nanocor). The dynamic behavior was investigated by using split Hopkinson pressure bars, at different strain rates and different temperatures. The obtained nanocomposite exhibits a good dispersion and a partially exfoliated morphology. To study the effect of nanocomposite dispersion and morphology on the dynamic behavior, another nanocomposite was prepared by melt mixing of polypropylene and a modified montmorillonite (dellite) (PP dellite). The dynamic property results for PP-nanocor show an increase of both Young’s modulus and yield stress with the increasing organoclay concentration. However, PP-dellite nanocomposites present poor mechanical properties compared with those of PP-nanocor. [DOI: 10.1115/1.4005420]

Engineering Polymer Microparticles by Droplet Microfluidics

Capillary-based flow-focusing and co-flow microsystems were developed to produce sphere-like polymer micro-particles of adjustable sizes in the range of 50 to 600 μm with a narrow size distribution (CV < 5%) and different morphologies (core–shell, janus, and capsules). Rod-like particles whose length was conveniently adjusted between 400 μm and few millimeters were also produced using the same microsystems. Influence of operating conditions (flow rate of the different fluid, microsystem characteristic dimensions, and design) as well as material parameters (viscosity of the different fluids and surface tension) was investigated. Empirical relationships were thus derived from experimental data to predict the microparticle’s overall size, shell thickness, or rods length. Besides morphology, microparticles with various compositions were synthesized and their potential applications highlighted: drug-loaded microparticles for new drug delivery strategies, composed inorganic–organic multiscale microparticles for sensorics, and liquid crystalline elastomer microparticles showing an anisotropic reversible shape change upon temperature for thermal actuators or artificial muscles.

Atom Transfer Radical Polymerization in Continuous Microflow: Effect of Process Parameters

We report on the synthesis of 2-(dimethylamino)ethyl methacrylate by atom transfer radical polymerization (ATRP) in tubular microreactors. Different process parameters, temperature, pressure, and shear rate, were considered to accelerate the reaction. Increase in temperature induced a faster reaction, but controlled nature of ATRP decreased past a threshold value that can be increased up to 95 °C by reducing the residence time. Positive effect of pressure was observed since significant increases in monomer conversion (+12.5 %) and molecular weight (+5,000 g/mol) were obtained. Moreover, polydispersity index was found to decrease from 1.52 at normal pressure to 1.44 at 100 bars. Benefit of pressure was more visible in smaller reaction space (smaller tube diameter). Finally, shear rate has quite an influence on the early stage of the polymerization and is expressed by an increase in the reaction rate. However, the effect was dimed for long residence times.

A new formulation of poly(MAOTIB) nanoparticles as an efficient contrast agent for in vivo X-ray imaging

Polymeric nanoparticles (PNPs) are gaining increasing importance as nanocarriers or contrasting material for preclinical diagnosis by micro-CT scanner. Here, we investigated a straightforward approach to produce a biocompatible, radiopaque, and stable polymer-based nanoparticle contrast agent, which was evaluated on mice. To this end, we used a nanoprecipitation dropping technique to obtain PEGylated PNPs from a preformed iodinated homopolymer, poly(MAOTIB), synthesized by radical polymerization of 2-methacryloyloxyethyl(2,3,5-triiodobenzoate) monomer (MAOTIB). The process developed allows an accurate control of the nanoparticle properties (mean size can range from 140 nm to 200 nm, tuned according to the formulation parameters) along with unprecedented important X-ray attenuation properties (concentration of iodine around 59 mg I/mL) compatible with a follow-up in vivo study. Routine characterizations such as FTIR, DSC, GPC, TGA, 1H and 13C NMR, and finally SEM were accomplished to obtain the main properties of the optimal contrast agent. Owing to excellent colloidal stability against physiological conditions evaluated in the presence of fetal bovine serum, the selected PNPs suspension was administered to mice. Monitoring and quantification by micro-CT showed that iodinated PNPs are endowed strong X-ray attenuation capacity toward blood pool and underwent a rapid and passive accumulation in the liver and spleen. STATEMENT OF SIGNIFICANCE The design of X-ray contrast agents for preclinical imaging is still highly challenging. To date, the best contrast agents reported are based on iodinated lipids or inorganic materials such as gold. In literature, several attempts were undertaken to create polymer-based X-ray contrast agents, but their applicability in vivo was limited to their low contrasting properties. Polymer-based contrast agents present the advantages of an easy surface modification for future application in targeting. Herein, we develop a novel approach to design polymer-based nanoparticle X-ray contrast agent (polymerization of a highly iodine-loaded monomer (MAOTIB)), leading to an iodine concentration of 59 mg/mL. We showed their high efficiency in vivo in mice, in terms of providing a strong signal in blood and then accumulating in the liver and spleen.