Model-Based Optimization of Microgel Synthesis in the μm Size Range

Abstract

Microgels are functional polymer colloids with diverse applications, for example, in medicine, engineering, or agriculture. Some applications require large microgels in the size range of μm, which could previously only be synthesized using microfluidics or a synthesis procedure involving a fed-batch reaction with a temperature ramp. We use dynamic optimization to determine a simpler synthesis recipe that allows us to synthesize microgels in the μm range using a batch procedure. First, a sensitivity analysis shows that the microgel size is sensitive to the initial concentration of initiator and the reactor temperature. Second, the dynamic optimization yields a batch recipe that provides microgels of the desired μm size range. The recipe uses a low initial initiator concentration and a low reactor temperature. The respective recipe is validated experimentally; model simulation results and experimental measurements of the hydrodynamic diameter show good agreement.

Surfactant-Free Synthesis of PNIPAM-Based Smart Microgels for Drug Delivery Using a High-Gravity Rotating Packed Bed

“…The later increase in particle size and D h was mainly due to the fierce collision, entanglement, and aggregation among the concentrated active chains, generating large gel particles. Our results demonstrated that the effects of the cross-linker and initiator on microgel size were consistent with that of the traditional batch reactor. − …”

“…In comparison, a conventional STR was used to synthesize PNIPAM microgels under the same reaction conditions as in the RPB. It took 6 h to react completely, as reported before . The results are shown in Table .…”

“…It took 6 h to react completely, as reported before. 36 The results are shown in Table 2. The as-prepared microgels presented good monodispersity as well; however, the particle size and D h hardly changed when varying the stirring speed from 300 to 1500 rpm.…”

Kinetic Modeling of a Poly(N-vinylcaprolactam-co-glycidyl methacrylate) Microgel Synthesis: A Hybrid In Silico and Experimental Approach

“…The efficiency of the initiator decomposition is set to 50%. 19 The kinetics of the propagation reactions depend only on the radical at the terminal end of the chain, and propagation reactions contribute majorly to the enthalpy release. Termination only occurs due to disproportionation, and the kinetics of termination reactions do not depend on the terminal end of the active radical chains, as they are mostly diffusion limited.…”

“…The model contains 21 parameters. Out of the 21 parameters, we adopt three propagation rate constant values, three polymerization enthalpy values, and the initiator efficiency value from our previous studies. , Using transition state theory and quantum chemical calculations, we compute 12 out of 21 parameters, namely, the propagation rate constants and polymerization enthalpies of GMA/VCL and GMA/BIS systems in an aqueous solution. We include all quantum chemically computed polymerization enthalpies and the model’s four least impactful propagation rate constants into the final model.…”