A subscription to JoVE is required to view this content. Sign in or start your free trial.
Non-stirred precipitation polymerization provides a rapid, reproducible prototyping approach to the synthesis of stimuli-sensitive poly(N-isopropylacrylamide) microgels of narrow size distribution. In this protocol synthesis, light scattering characterization and single particle fluorescence tracking of these microgels in a wide-field microscopy setup are demonstrated.
Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this work, we use single particle tracking of fluorescently labeled PNIPAM microgels as a showcase for tuning microgel size by a rapid non-stirred precipitation polymerization procedure. This approach is well suited for prototyping new reaction compositions and conditions or for applications that do not require large amounts of product. Microgel synthesis, particle size and structure determination by dynamic and static light scattering are detailed in the protocol. It is shown that the addition of functional comonomers can have a large influence on the particle nucleation and structure. Single particle tracking by wide-field fluorescence microscopy allows for an investigation of the diffusion of labeled tracer microgels in a concentrated matrix of non-labeled microgels, a system not easily investigated by other methods such as dynamic light scattering.
Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels 1,2 have attracted continuous interest over the past two decades due to their potential in various smart applications. Demonstrated use cases include switchable emulsion stabilizers 3-8, microlenses 9, cell culture substrates for easy cell harvesting 10,11, and smart carriers for low molecular weight compounds and other biomedical uses 12. From a fundamental research point of view these particles have been proven to be useful for investigating subjects such as colloidal interactions 13-15 and polymer-solvent interactions 16-1....
1. Microgel Synthesis
NOTE: N-isopropylacrylamide (NIPAM) was recrystallized from n-hexane. Other reagents were used as received.
The number of PNIPAM microgel particles in the batch, and thus the final particle volume, is determined early in the reaction during the nucleation phase 20 Hydrophobic co-monomer dye methacryloxyethyl thiocarbamoyl rhodamine B influences the nucleation by reducing the particle number density in the batch. The decrease in particle concentration for two different initial NIPAM concentrations can be seen as increase in.......
Addition of small amounts of functional comonomer can have a significant effect on the particle size and structure of the PNIPAM derived microgels. Simultaneous small-scale test tube polymerization is a good method to account for such changes, and helps to rapidly find the right reactant compositions for target particle size for upscaling the reaction as needed. The mass of the particles is approximately exponentially dependent on the .......
The authors have nothing to disclose.
The Deutsche Forschungsgemeinschaft (DFG) is acknowledged for financial support within the Sonderforschungsbereich SFB 985 "Functional Microgels and Microgel Systems".
....Name | Company | Catalog Number | Comments |
Acetone | VWR Chemicals | KRAF13455 | |
Bisacrylamid | AppliChem | A3636 | |
n-Hexane | Merck | 104374 | |
N-Isopropylacrylamide | Fisher Scientific | AC412785000 | recrystallized from n-hexane |
Methacryloxyethyl thiocarbamoyl rhodamine B | Polysciences | 23591 | |
Potassium peroxodisulfate | Merck | 105091 | |
Silicone oil 47 V 350 | VWR Chemicals | 83851 | |
Toluene | Sigma Aldrich | 244511 | |
F12 Refrigerated/heating circulator | Julabo | 9116612 | |
Microscope | Olympus | IX83 | |
XY(Z) Piezo System | Physik Instrumente | P-545.3R7 | |
100x Oil immersion objective | Olympus | UPLSAPO | |
QuadLine Beamsplitter | AHF Analysentechnik | F68-556T | |
Cobolt Jive 150 laser | Cobolt | 0561-04-01-0150-300 | |
Multimode Fiber | Thorlabs | UM22-600 | |
iXON Ultra 897 EMCCD camera | Andor | DU-897U-CS0-BV | |
Laser goniometer | SLS Systemtechnik | Mark III | |
CF40 Cryo-compact circulator | Julabo | 9400340 | |
Laser goniometer system | ALV GmbH | ALV / CGS-8F | |
Multi-tau corretator | ALV GmbH | ALV-7004 | |
Light scattering electronics | ALV GmbH | ALV / LSE 5004 | |
Photon counting module | PerkinElmer | SPCM-CD2969 | 2 units in pseudo cross-correlation mode |
633 nm HeNe Laser | JDS Uniphase | 1145P | |
F32 Refrigerated/heating circulator | Julabo | 9312632 |
Request permission to reuse the text or figures of this JoVE article
Request PermissionThis article has been published
Video Coming Soon
ABOUT JoVE
Copyright © 2025 MyJoVE Corporation. All rights reserved