Production of spherical mesoporous molecularly imprinted polymer particles containing tunable amine decorated nanocavities with CO2 molecule recognition properties

Novel spherical molecularly imprinted polymer (MIP) particles containing amide-decorated nanocavities with CO2 recognition properties in the poly[acrylamide-co-(ethyleneglycol dimethacrylate)] mesoporous matrix were synthesized by suspension polymerization using oxalic acid and acetonitrile/toluene as dummy template and porogen mixture, respectively. The particles had a maximum BET surface area, SBET, of 457 m2/g and a total mesopore volume of 0.92 cm3/g created by phase separation between the copolymer and porogenic solvents. The total volume of the micropores (d < 2 nm) was 0.1 cm3/g with two sharp peaks at 0.84 and 0.85 nm that have not been detected in non-imprinted polymer material. The degradation temperature at 5% weight loss was 240–255 °C and the maximum equilibrium CO2 adsorption capacity was 0.56 and 0.62 mmol/g at 40 and 25 °C, respectively, and 0.15 bar CO2 partial pressure. The CO2 adsorption capacity was mainly affected by the density of CO2-philic NH2 groups in the polymer network and the number of nanocavities. Increasing the content of low-polar solvent (toluene) in the organic phase prior to polymerization led to higher CO2 capture capacity due to stronger hydrogen bonds between the template and the monomer during complex formation. Under the same conditions, molecularly imprinted particles showed much higher CO2 capture capacity compared to their non-imprinted counterparts. The volume median diameter (73–211 μm) and density (1.3 g/cm3) of the produced particles were within the range suitable for CO2 capture in fixed and fluidized bed systems

Mechanisms and control of single-step microfluidic generation of multi-core double emulsion droplets

Single-step generation of monodisperse multi-core double emulsion drops in three-phase glass capillary microfluidic device was investigated using a micro-particle image velocimetry (micro-PIV) system. Phase diagrams were developed to predict the number of encapsulated inner drops as a function of the capillary numbers of inner, middle and outer fluid. The maximum stable number of inner drops cores in uniform double emulsion drops was six. Starting from core/shell drops, the formation of double emulsion drops with multiple cores was achieved by decreasing the capillary number of the outer fluid and increasing the capillary number of the middle fluid. A stable continuous jet of the middle fluid loaded with inner drops was formed at high capillary numbers of the middle fluid. Empirical correlations predicting the size and generation frequency of inner drops as a function of the capillary numbers and the device geometry were developed. Dual-core double emulsion drops were used as templates for the fabrication of polymeric capsules using “on-the-fly” photopolymerisation. The capsule morphology was controlled by manipulating the stability of the inner drops through adjusting the concentration of the lipophilic surfactant in the middle fluid. At low concentration of the lipophilic surfactant, inner drop coalesced during curing and single compartment capsules with thin shells were produced from dual-core drops. The core/shell capsules produced from multi-core drops were monodispersed and larger than those produced from core/shell drops in the same device

Synthesis of size-tuneable CO2-philic imprinted polymeric particles (MIPs) for low-pressure CO2 capture using oil-in-oil suspension polymerisation

Highly selective molecularly imprinted poly[ acrylamide-co-(ethylene glycol dimethacrylate)] polymer particles (MIPs) for CO2 capture were synthesized by suspension polymerization via oil-in-oil emulsion. Creation of CO2-philic, amide-decorated cavities in the polymer matrix led to a high affinity to CO2. At 0.15 bar CO2 partial pressure, the CO2/N2 selectivity was 49 (corresponding to 91% purity of the gas stream after regeneration), and reached 97 at ultralow CO2 partial pressures. The imprinted polymers showed considerably higher CO2 uptakes compared to their nonimprinted counterparts, and the maximum equilibrium CO2 capture capacity of 1.1 mmol g−1 was achieved at 273 K. The heat of adsorption was below 32 kJ mol−1 and the temperature of onset of intense thermal degradation was 351−376 °C. An increase in monomer-to-cross-linker molar ratio in the dispersed phase up to 1:2.5 led to a higher affinity toward CO2 due to higher density of selective amide groups in the polymer network. MIPs are a promising option for industrial packed and fluidized bed CO2 capture systems due to large particles with a diameter up to 1200 μm and irregular oblong shapes formed due to arrested coalescence during polymerization, occurring as a result of internal elasticity of the partially polymerized semisolid drops

Production of uniform droplets using membrane, microchannel and microfluidic emulsification devices

This review provides an overview of major microengineering emulsification techniques for production of monodispersed droplets. The main emphasis has been put on membrane emulsification using Shirasu Porous Glass and microsieve membrane, microchannel emulsification using grooved-type and straight-through microchannel plates, microfluidic junctions and flow focusing microfluidic devices. Microfabrication methods for production of planar and 3D poly(dimethylsiloxane) devices, glass capillary microfluidic devices and single-crystal silicon microchannel array devices have been described including soft lithography, glass capillary pulling and microforging, hot embossing, anisotropic wet etching and deep reactive ion etching. In addition, fabrication methods for SPG and microseive membranes have been outlined, such as spinodal decomposition, reactive ion etching and ultraviolet LIGA (Lithography, Electroplating, and Moulding) process. The most widespread application of micromachined emulsification devices is in the synthesis of monodispersed particles and vesicles, such as polymeric particles, microgels, solid lipid particles, Janus particles, and functional vesicles (liposomes, polymersomes and colloidosomes). Glass capillary microfluidic devices are very suitable for production of core/shell drops of controllable shell thickness and multiple emulsions containing a controlled number of inner droplets and/or inner droplets of two or more distinct phases. Microchannel emulsification is a very promising technique for production of monodispersed droplets with droplet throughputs of up to 100 l h−1

Production of molecularly imprinted polymer particles with amide-decorated cavities for CO2 capture using membrane emulsification/suspension polymerisation

Highly uniform amide-based molecularly imprinted polymer (MIP) particles containing CO2-philic cavities decorated with amide groups were produced using membrane emulsification and subsequent suspension polymerisation. The organic phase containing acrylamide (functional monomer), oxalic acid (dummy template), ethylene glycol dimethacrylate (crosslinker) and azobisisobutyronitrile (initiator) dissolved in a 50/50 mixture (by volume) of acetonitrile and toluene (porogenic solvents) was injected through a microengineered nickel membrane with a pore diameter of 20 μm and a pore spacing of 200 μm into agitated 0.5 wt% aqueous solution of poly(vinyl alcohol) to form droplets that have been polymerised at 60 °C for 3 h. The volume median diameter of the droplets was controlled between 35 and 158 μm by shear stress at the membrane surface. The droplets maintained their physical stability during storage for 4 weeks and their size was independent of the dispersed phase content. The particle size after polymerisation was consistent with the initial droplet size. The particles were stable up to 210 °C and had a specific surface area of 239 m2/g and a CO2 capture capacity of 0.59 mmol/g at 273 K and 0.15 bar CO2 partial pressure

Production of biocompatible gold nanoparticles for drug delivery using droplet based glass capillary microfluidic [Abstract]

Production of biocompatible gold nanoparticles for drug delivery using droplet based glass capillary microfluidic [Abstract

Production of porous silica microparticles by membrane emulsification

A method for the production of near-monodispersed spherical silica particles with controllable porosity based on the formation of uniform emulsion droplets using membrane emulsification is described. A hydrophobic metal membrane with a 15 μm pore size and 200 μm pore spacing was used to produce near-monodispersed droplets, with a mean size that could be controlled between 65 and 240 μm containing acidified sodium silicate solution (with 4 and 6 wt % SiO2) in kerosene. After drying and shrinking, the final silica particles had a mean size in the range between 30 and 70 μm. The coefficient of variation for both the droplets and the particles did not exceed 35%. The most uniform particles had a mean diameter of 40 μm and coefficient of variation of 17%. By altering the pH of the sodium silicate solution and aging the gel particles in water or acetone, the internal structure of the silica particles was successfully modified, and both micro- and mesoporous near-monodispersed spherical particles were produced with an average internal pore size between 1 and 6 nm and an average surface area between 360 and 750 m2 g–1. A material balance and particle size analysis provided identical values for the internal voidage of the particles, when compared to the voidage as determined by BET analysis

Novel membrane emulsification method of producing highly uniform silica particles using inexpensive silica sources

A membrane emulsification method for production of monodispersed silica-based ion exchange particles through water-in-oil emulsion route is developed. A hydrophobic microsieve membrane with 15 :m pore size and 200 :m pore spacing was used to produce droplets, with a mean size between 65 and 240 :m containing acidified sodium silicate solution (with 4 and 6% wt. SiO2) in kerosene. After drying, the final silica particles had a mean size in the range between 30 and 70 :m. Coefficient of variation for both the droplets and particles did not exceed 35%. The most uniform particles had a mean diameter of 40 :m and coefficient of variation of 17%. The particles were functionalised with 3-aminopropyltrimethoxysilane and used for chemisorption of Cu(II) from an aqueous solution of CuSO4 in a continuous flow stirred cell with slotted pore microfiltration membrane. Functionalised silica particles showed a higher binding affinity toward Cu(II) than non-treated silica particles

Novel method of producing highly uniform silica particles using inexpensive silica sources

Novel method of producing highly uniform silica particles using inexpensive silica source

Production of silica particles by membrane emulsification

Production of silica particles by membrane emulsificatio