| dc.description.abstract | Use of polymeric nanoparticles has gained significant interest in recent years for a wide spectrum of applications such as drug delivery, cell imaging, environmental remediation, and, electronics. However, many of these nanoparticles have been mainly synthesized at the laboratory scale. Large scale synthesis of these nanoparticles in a cost-effective and reliable fashion could significantly expand their industrial use. In many cases, self-assembly of block polymers into different morphologies involves a transition from a solvated polymer in an organic solvent to a fully aqueous system. Here, the feasibility of using tangential flow filtration (TFF) to scale-up the solution-state transition was studied. A custom-designed and chemically resistant experimental TFF system was built. Nine TFF experiments were performed to study the effects of change of transmembrane pressure, nanoparticles concentration, and hydrophobic/hydrophilic block ratio on solvent removal and nanoparticle size evolution during the diafiltration process. In addition, three batch dialysis experiments were performed to understand the possible extent of scale-up using the proposed system.
The designed experimental setup had considerable chemical resistance to many solvents and could be used to conduct small-molecule removal, scaleup, and concentration processes on a wide range of polymers. Feasibility of use of TFF for purification of amphiphilic polymeric nanoparticles with core-shell morphology was demonstrated. Solvent exchange using TFF was considerably faster compared to the traditional batch dialysis system. In TFF experiments, the organic solvent concentration reached the minimum level after 1 hour of in-flow filtration, while it took around 6 hours to reach similar levels of solvent exchange in the batch setting. In addition to an order of magnitude higher processing volumes of TFF compared to dialysis, further scale-up of the TFF process is easily achievable with increasing the membrane area. As expected, higher transmembrane pressure resulted in faster organic solvent removal. The initial nanoparticles concentration had a significant effect on the diameter of the formed structures during the TFF purification, which affected the required purification time. A high ratio of hydrophobic to hydrophilic blocks in a block copolymer increases the chance of precipitation of nanoparticle during TFF, which might terminate the process. | en |
