Core–shell microgels synthesized in continuous flow: deep insight into shell growth using temperature-dependent FTIR

Fandrich, Pascal; Annegarn, Marco; Wiehemeier, Lars; Ehring, Ina; Kottke, Tilman; Hellweg, Thomas

doi:10.1039/d2sm00598k

Cited by 5 publications

(4 citation statements)

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“…It has to be kept in mind that the core in the core‐shell microgels presumably has smaller dimensions, as the shell is synthesized onto a collapsed version of the core. [ 50 ] Because of this, no quantitative statements regarding the size of the shell can be made.…”

Section: Resultsmentioning

confidence: 99%

Unusual Shell Morphologies of Responsive Amino Core‐Shell Microgels Induced by pH During Shell Synthesis

Annegarn,

Ehring,

Hellweg

2023

Macro Chemistry & Physics

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The properties of pH‐responsive microgels are strongly influenced by the pH value during synthesis. In this work, based on a N‐n‐propylacrylamide (NNPAM) core with N‐3‐(dimethylamino)propylmethacrylamide (DAPMA) as a comonomer, a series of core‐shell microgels with shells from NNPAM and N‐(3‐aminopropyl)methacrylamide hydrochloride (APMH) were synthesized at different pH values. While the swelling behavior was studied with temperature‐ and angle‐dependent photon correlation spectroscopy (PCS), the size and morphology were also investigated by means of atomic force microscopy (AFM) and static light scattering (SLS). At acidic pH, rather monodisperse microgels with a very fuzzy shell are obtained. The microgels evolve particulate structures on their shell at intermediate pH until not only a core‐shell microgel but also a secondary microgel species is produced at basic pH. By altering the synthesis pH, it is possible to influence the morphology of core‐shell microgels to suit future applications like uptake and release of drugs or surface modification.This article is protected by copyright. All rights reserved

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Section: Resultsmentioning

confidence: 99%

Unusual Shell Morphologies of Responsive Amino Core‐Shell Microgels Induced by pH During Shell Synthesis

Annegarn,

Ehring,

Hellweg

2023

Macro Chemistry & Physics

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“…The reactor was heated to 80 °C (Haake DC10, Thermo Fisher Scientific, Waltham, MA). In earlier works, we have shown that the desired temperature is reached after a finite heat-up time of 23 s, while the cooled stock solution remained stable over several hours . The microgels investigated by photon correlation spectroscopy were synthesized without the SAXS setup as sampling in the sample environment was not possible.…”

Section: Methodsmentioning

confidence: 99%

“…In earlier works, we have shown that the desired temperature is reached after a finite heat-up time of 23 s, while the cooled stock solution remained stable over several hours. 33 The microgels investigated by photon correlation spectroscopy were synthesized without the SAXS setup as sampling in the sample environment was not possible. These microgels were directly quenched in liquid nitrogen after leaving the reactor.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Nevertheless, Wolff and co-workers have successfully synthesized poly( N -vinylcaprolactam) and PNIPAM microgels in a continuous precipitation polymerization . In earlier works, our group was able to monitor the NIPAM conversion with in situ FTIR spectroscopy in a continuous flow setup and successfully synthesized core–shell architectures. , Later, Kaven and co-workers reported in-line Raman spectroscopy for flow reactors . In combination with small-angle X-ray scattering (SAXS), a variety of time-resolved experiments with continuous flow mixers can be found in the literature in systems such as surfactants, , proteins, , and microfluidic devices. ,, …”

Section: Introductionmentioning

confidence: 99%

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Growth of Smart Microgels in a Flow Reactor Scrutinized by In-Line SAXS

et al. 2023

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In this work, a continuous flow setup for in situ investigation of microgel growth with small-angle X-ray scattering (SAXS) is established. Poly(N-n-propylacrylamide) (PNNPAM) and poly(N-isopropylacrylamide) (PNIPAM) microgels are synthesized in H2O at different residence times inside a continuous flow reactor. The microgels are investigated by in situ SAXS and ex situ photon correlation spectroscopy. The size of the microgels was found to be reproducible in independent experiments with run times of up to 7 h. Already the scattering curves of the microgels with a time of residence of 15 min show a well-defined form factor. Further analysis of the scattering profiles confirms the spherical shape of the microgels. At a residence time of 2 min, the scattering intensity is significantly lower corresponding to a smaller particle size. The experimental conditions remain constant over time, which is crucial for long-time experiments. The PNNPAM system is found to be more suitable for the flow reactor experiment with in-line SAXS as it shows less polymer deposition in the tubing and forms particles with lower polydispersity. The presented reactor is characterized by a compact design and offers a plug-and-play setup close to the sample environment. This work paves the way for investigations of microgel growth at e.g. synchrotron X-ray beamlines.

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Core-shell systems of crosslinked organic polymers: A critical review

Arif

2024

European Polymer Journal

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Core–shell microgels synthesized in continuous flow: deep insight into shell growth using temperature-dependent FTIR

Abstract: While core-shell microgels have been intensively studied in their fully synthesized state, the formation mechanism of the shell has not been completely understood. Such insight is decisive for a customization...

Cited by 5 publications

References 57 publications

Unusual Shell Morphologies of Responsive Amino Core‐Shell Microgels Induced by pH During Shell Synthesis

Unusual Shell Morphologies of Responsive Amino Core‐Shell Microgels Induced by pH During Shell Synthesis

Growth of Smart Microgels in a Flow Reactor Scrutinized by In-Line SAXS

Core-shell systems of crosslinked organic polymers: A critical review

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