@article{59510,
  abstract     = {{<jats:p>The use of organo-catalysis in continuous-flow reactor systems is gaining attention in medicinal chemistry due to its cost-effectiveness and reduced chemical waste. In this study, bioactive curcumin (CUM) derivatives were synthesized in a continuously operated microfluidic reactor (MFR), using piperidine-based polymeric networks as catalysts. Piperidine methacrylate and piperidine acrylate were synthesized and subsequently copolymerized with complementary monomers (MMA or DMAA) and crosslinkers (EGDMA or MBAM) via photopolymerization, yielding different polymeric networks. Initially, batch reactions were optimized for the organo-catalytic Knoevenagel condensation between CUM and 4-nitrobenzaldehyde, under various conditions, in the presence of polymer networks. Conversion was assessed using offline 1H NMR spectroscopy, revealing an increase in conversion with enhanced swelling properties of the polymer networks, which facilitated greater accessibility of catalytic sites. In continuous-flow MFR experiments, optimized polymer gel dots exhibited superior catalytic performance, achieving a conversion of up to 72%, compared to other compositions. This improvement was attributed to the enhanced swelling in the reaction mixture (DMSO/methanol, 7:3 v/v) at 40 °C over 72 h. Furthermore, the MFR system enabled the efficient synthesis of a series of CUM derivatives, demonstrating significantly higher conversion rates than traditional batch reactions. Notably, while batch reactions required 90% catalyst loading in the gel, the MFR system achieved a comparable or superior performance with only 50% catalyst, resulting in a higher turnover number. These findings underscore the advantages of continuous-flow organo-catalysis in enhancing catalytic efficiency and sustainability in organic synthesis.</jats:p>}},
  author       = {{Killi, Naresh and Rumpke, Katja and Kuckling, Dirk}},
  issn         = {{2310-2861}},
  journal      = {{Gels}},
  keywords     = {{flow chemistry, heterogeneous catalysis, sustainable synthesis, organo-catalysis, polymeric gel dots}},
  number       = {{4}},
  publisher    = {{MDPI AG}},
  title        = {{{Synthesis of Curcumin Derivatives via Knoevenagel Reaction Within a Continuously Driven Microfluidic Reactor Using Polymeric Networks Containing Piperidine as a Catalyst}}},
  doi          = {{10.3390/gels11040278}},
  volume       = {{11}},
  year         = {{2025}},
}

@article{53166,
  abstract     = {{<jats:p>The Knoevenagel reaction is a classic reaction in organic chemistry for the formation of C-C bonds. In this study, various catalytic monomers for Knoevenagel reactions were synthesized and polymerized via photolithography to form polymeric gel dots with a composition of 90% catalyst, 9% gelling agent and 1% crosslinker. Furthermore, these gel dots were inserted into a microfluidic reactor (MFR) and the conversion of the reaction using gel dots as catalysts in the MFR for 8 h at room temperature was studied. The gel dots containing primary amines showed a better conversion of about 83–90% with aliphatic aldehyde and 86–100% with aromatic aldehyde, compared to the tertiary amines (52–59% with aliphatic aldehyde and 77–93% with aromatic aldehydes) which resembles the reactivity of the amines. Moreover, the addition of polar solvent (water) in the reaction mixture and the swelling properties of the gel dots by altering the polymer backbone showed a significant enhancement in the conversion of the reaction, due to the increased accessibility of the catalytic sites in the polymeric network. These results suggested the primary-amine-based catalysts facilitate better conversion compared to tertiary amines and the reaction solvent had a significant influence on organocatalysis to improve the efficiency of MFR.</jats:p>}},
  author       = {{Killi, Naresh and Bartenbach, Julian and Kuckling, Dirk}},
  issn         = {{2310-2861}},
  journal      = {{Gels}},
  keywords     = {{Knoevenagel reaction, organocatalysis, polymeric gel dots, microfluidic reactions, polymeric networks}},
  number       = {{3}},
  publisher    = {{MDPI AG}},
  title        = {{{Polymeric Networks Containing Amine Derivatives as Organocatalysts for Knoevenagel Reaction within Continuously Driven Microfluidic Reactors}}},
  doi          = {{10.3390/gels9030171}},
  volume       = {{9}},
  year         = {{2023}},
}

@article{35642,
  abstract     = {{<jats:p>There is an increasing interest in sensing applications for a variety of analytes in aqueous environments, as conventional methods do not work reliably under humid conditions or they require complex equipment with experienced operators. Hydrogel sensors are easy to fabricate, are incredibly sensitive, and have broad dynamic ranges. Experiments on their robustness, reliability, and reusability have indicated the possible long-term applications of these systems in a variety of fields, including disease diagnosis, detection of pharmaceuticals, and in environmental testing. It is possible to produce hydrogels, which, upon sensing a specific analyte, can adsorb it onto their 3D-structure and can therefore be used to remove them from a given environment. High specificity can be obtained by using molecularly imprinted polymers. Typical detection principles involve optical methods including fluorescence and chemiluminescence, and volume changes in colloidal photonic crystals, as well as electrochemical methods. Here, we explore the current research utilizing hydrogel-based sensors in three main areas: (1) biomedical applications, (2) for detecting and quantifying pharmaceuticals of interest, and (3) detecting and quantifying environmental contaminants in aqueous environments.</jats:p>}},
  author       = {{Völlmecke, Katharina and Afroz, Rowshon and Bierbach, Sascha and Brenker, Lee Josephine and Frücht, Sebastian and Glass, Alexandra and Giebelhaus, Ryland and Hoppe, Axel and Kanemaru, Karen and Lazarek, Michal and Rabbe, Lukas and Song, Longfei and Velasco Suarez, Andrea and Wu, Shuang and Serpe, Michael and Kuckling, Dirk}},
  issn         = {{2310-2861}},
  journal      = {{Gels}},
  keywords     = {{Polymers and Plastics, Organic Chemistry, Biomaterials, Bioengineering}},
  number       = {{12}},
  publisher    = {{MDPI AG}},
  title        = {{{Hydrogel-Based Biosensors}}},
  doi          = {{10.3390/gels8120768}},
  volume       = {{8}},
  year         = {{2022}},
}

@article{59617,
  abstract     = {{<jats:p>There is an increasing interest in sensing applications for a variety of analytes in aqueous environments, as conventional methods do not work reliably under humid conditions or they require complex equipment with experienced operators. Hydrogel sensors are easy to fabricate, are incredibly sensitive, and have broad dynamic ranges. Experiments on their robustness, reliability, and reusability have indicated the possible long-term applications of these systems in a variety of fields, including disease diagnosis, detection of pharmaceuticals, and in environmental testing. It is possible to produce hydrogels, which, upon sensing a specific analyte, can adsorb it onto their 3D-structure and can therefore be used to remove them from a given environment. High specificity can be obtained by using molecularly imprinted polymers. Typical detection principles involve optical methods including fluorescence and chemiluminescence, and volume changes in colloidal photonic crystals, as well as electrochemical methods. Here, we explore the current research utilizing hydrogel-based sensors in three main areas: (1) biomedical applications, (2) for detecting and quantifying pharmaceuticals of interest, and (3) detecting and quantifying environmental contaminants in aqueous environments.</jats:p>}},
  author       = {{Völlmecke, Katharina and Afroz, Rowshon and Bierbach, Sascha and Brenker, Lee Josephine and Frücht, Sebastian and Glass, Alexandra and Giebelhaus, Ryland and Hoppe, Axel and Kanemaru, Karen and Lazarek, Michal and Rabbe, Lukas and Song, Longfei and Velasco Suarez, Andrea and Wu, Shuang and Serpe, Michael and Kuckling, Dirk}},
  issn         = {{2310-2861}},
  journal      = {{Gels}},
  number       = {{12}},
  publisher    = {{MDPI AG}},
  title        = {{{Hydrogel-Based Biosensors}}},
  doi          = {{10.3390/gels8120768}},
  volume       = {{8}},
  year         = {{2022}},
}

@article{23856,
  author       = {{Berg, Patrik and Prowald, Carsten Dieter and Kuckling, Dirk}},
  issn         = {{2310-2861}},
  journal      = {{Gels}},
  number       = {{2}},
  publisher    = {{MDPI}},
  title        = {{{Investigation of Gel Properties of Novel Cryo-Clay-Silica Polymer Networks}}},
  doi          = {{10.3390/gels6020011}},
  volume       = {{6}},
  year         = {{2020}},
}

@article{35330,
  abstract     = {{<jats:p>Gelled lyotropic liquid crystals can be formed by adding a gelator to a mixture of surfactant and solvent. If the gel network and the liquid-crystalline phase coexist without influencing each other, the self-assembly is called orthogonal. In this study, the influence of the organogelator 12-hydroxyoctadecanoic acid (12-HOA) on the lamellar and hexagonal liquid crystalline phases of the binary system H2O–C12E7 (heptaethylene glycol monododecyl ether) is investigated. More precisely, we added 12-HOA at mass fractions from 0.015 to 0.05 and studied the resulting phase diagram of the system H2O–C12E7 by visual observation of birefringence and by 2H NMR spectroscopy. In addition, the dynamic shear moduli of the samples were measured in order to examine their gel character. The results show that 12-HOA is partly acting as co-surfactant, manifested by the destabilization of the hexagonal phase and the stabilization of the lamellar phase. The higher the total surfactant concentration, the more 12-HOA is incorporated in the surfactant layer. Accordingly, its gelation capacity is substantially reduced in the surfactant solution compared to the system 12-HOA–n-decane, and large amounts of gelator are required for gels to form, especially in the lamellar phase.</jats:p>}},
  author       = {{Steck, Katja and Schmidt, Claudia and Stubenrauch, Cosima}},
  issn         = {{2310-2861}},
  journal      = {{Gels}},
  keywords     = {{Polymers and Plastics, Organic Chemistry, Biomaterials, Bioengineering}},
  number       = {{3}},
  publisher    = {{MDPI AG}},
  title        = {{{The Twofold Role of 12-Hydroxyoctadecanoic Acid (12-HOA) in a Ternary Water—Surfactant—12-HOA System: Gelator and Co-Surfactant}}},
  doi          = {{10.3390/gels4030078}},
  volume       = {{4}},
  year         = {{2018}},
}

@article{25909,
  abstract     = {{Organic polymer-hydrogels are known to be capable of directing the nucleation and growth of inorganic materials, such as silica, metal oxides, apatite or metal chalcogenides. This approach can be exploited in the synthesis of materials that exhibit defined nanoporosity. When the organic polymer-based hydrogel is incorporated in the inorganic product, a composite is formed from which the organic component may be selectively removed, yielding nanopores in the inorganic product. Such porogenic impact resembles the concept of using soft or hard templates for porous materials. This micro-review provides a survey of select examples from the literature.}},
  author       = {{Weinberger, Christian and Kuckling, Dirk and Tiemann, Michael}},
  issn         = {{2310-2861}},
  journal      = {{Gels}},
  title        = {{{Hydrogels as Porogens for Nanoporous Inorganic Materials}}},
  doi          = {{10.3390/gels4040083}},
  year         = {{2018}},
}