Swelling-Activated, Soft Mechanochemistry in Polymer Materials

Metze, Friederike K.; Sant, Sabrina; Zhao, Meng; Klok, Harm‐Anton; Kaur, Kuljeet

doi:10.1021/acs.langmuir.2c02801

Cited by 47 publications

(26 citation statements)

References 88 publications

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“…When the gel experienced stretching due to osmotic pressure-induced swelling, the polymer chains disentangled and dispersed throughout the smectite, disrupting the J-aggregate that had been adsorbed on the surface (Figure ). This particular phenomenon differs from other systems such as cross-linked polymer networks and mechanochromic blends, where the disruption of dye occurs in the amorphous regions of the polymer during stretching. − The coloration relied not only on the degree of swelling but also on the stability of the PIC monomer in the permeating solvent and the orientation of the smectite in the gel. The PIC J-aggregate was transformed into the monomer upon swelling and distorted due to the surrounding solvent.…”

Section: Resultsmentioning

confidence: 93%

Swelling-Induced Chromotropism of Bionanocomposite Hydrogel Beads

Saengdet,

Ogawa

2023

Langmuir

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Monodispersed gelatin hydrogel beads containing smectite with adsorbed cyanine dye exhibit chromotropic responses to compression and swelling/deswelling by solvent. Photoluminescence color of the beads changes by swelling in water (blue) and deswelling in ethanol (purple) reversibly. The forces generated by swelling/deswelling are thought to induce the transition between the J-aggregate and the monomer of cyanine dye adsorbed on smectite, giving the photoluminescent color changes.

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Section: Resultsmentioning

confidence: 93%

Swelling-Induced Chromotropism of Bionanocomposite Hydrogel Beads

Saengdet,

Ogawa

2023

Langmuir

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“…Polyelectrolyte chains are prone to swelling when suspended in either a good solvent due to the favorable solvent–polymer interactions that maximize the polymer–solvent contact area or salt solutions as the osmotic pressure gradient can trigger diffusion and absorption of counterions in the interior of the brush . This swelling is counterbalanced by an elastic retractive force due to the reduced entropy by the segmental chain stretching that decreases the entropically accessible configurations. , Capturing the swelling thresholds for the grated polymer chains is desirable to modulate surface properties, including roughness, stiffness, and adhesion. Detailed size measurements in the presence of various electrolytes (NaCl, Na 2 SO 4 , and MgCl 2 ) were conducted using suspensions of S31+ as a model system.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Raspberry-like Nanoparticles via Surface Grafting of Positively Charged Polyelectrolyte Brushes: Colloidal Stability and Surface Properties

Aldakkan,

Chalmpes,

et al. 2024

Langmuir

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A method to synthesize stable, raspberry-like nanoparticles (NPs), using surface grafting of poly(glycidyl methacrylate) (PGMA) brushes on a polystyrene (PS) core with varying grafting densities, is reported. A twostep functionalization reaction of PGMA epoxide groups comprising an amination step first using ethylene diamine and then followed by a quaternization using glycidyltrimethylammonium chloride generates permanently and positively charged polyelectrolyte brushes, which result in both steric and electrostatic stabilization. The dispersion stability of the brush-bearing NPs is dramatically improved compared to that of the pristine PS core in salt solutions at ambient (25 °C) and elevated temperatures (60 °C). Additionally, the grafted polyelectrolyte chains undergo a reversible swelling in the presence of different ionic strength (IS) salts, which modulate the surface properties, including roughness, stiffness, and adhesion. An atomic force microscope under both dry and wet conditions was used to image conformational changes of the polyelectrolyte chains during the swelling and deswelling transitions as well as to probe the nanomechanical properties by analyzing the corresponding force−sample separation curves. The quaternized polyelectrolyte brushes undergo a conformational transition from a collapsed state to a swelled state in the osmotic brush (OB) regime triggered by the osmotic gradient of mobile ions to the interior of the polymer chain. At IS ∼ 1 M, the brushes contract and the globules reform (salted brush state) as evidenced by an increase in the surface roughness and a reduction in the adhesion of the brushes. Beyond IS ∼ 1 M, quartz crystal microbalance with dissipation monitoring measurements show that salt uptake continues to take place predominantly on the exterior surface of the brush since salt adsorption is not accompanied by a size increase as measured by dynamic light scattering. The study adds new insights into our understanding of the behavior of NPs bearing salt-responsive polyelectrolyte brushes with adaptive swelling thresholds that can ultimately modulate surface properties.

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“…However, it remains challenging to study what happens once the material is in its swollen state. When solvent molecules penetrate the network structure, the network is being stretched outward, first resulting in a swollen state . In order to compensate this outward force, bond exchange reactions could cause the polymer chains to rearrange, similar to stress–relaxation mechanisms.…”

Section: Resultsmentioning

confidence: 99%

Probing the Solubility of Imine-Based Covalent Adaptable Networks

Schoustra,

Asadi,

Smulders

2023

ACS Appl. Polym. Mater.

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Covalent adaptable networks (CANs) are polymer materials that are covalently cross-linked via dynamic covalent bonds. The cross-linked polymer network is generally expected to be insoluble, as is seen for traditional thermosets. However, in recent years, it has become apparent that�under certain conditions�both dissociative and associative CANs can be dissolved in a good solvent. For some applications (e.g., those that require long-term (chemical) stability), the solubility of CANs can be problematic. However, many forget that (selective) solubility of CANs can also be applied advantageously, for example, in recycling or modification of the materials. In this work, we provide results and insights related to the tunable solubility of iminebased CANs. We observed that selected CANs could be fully dissolved in a good solvent without observing dissociation of imines. Only in an acidic environment (partial) dissociation of imines was observed, which could be reverted to the associated state by addition of a base. By adjusting the network composition, we were able to either facilitate or hamper solubility as well as control the size of the dissolved particles. DLS showed that the size of dissolved polymer particles decreased at lower concentrations. Similarly, decreasing cross-linking density resulted in smaller particles. Last, we showed that we could use the solubility of the CANs as a means for chemical recycling and postpolymerization modification. The combination of our studies with existing literature provides a better understanding of the solubility of CANs and their applications as recyclable thermosets.

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Swelling-Activated, Soft Mechanochemistry in Polymer Materials

Cited by 47 publications

References 88 publications

Swelling-Induced Chromotropism of Bionanocomposite Hydrogel Beads

Swelling-Induced Chromotropism of Bionanocomposite Hydrogel Beads

Synthesis of Raspberry-like Nanoparticles via Surface Grafting of Positively Charged Polyelectrolyte Brushes: Colloidal Stability and Surface Properties

Probing the Solubility of Imine-Based Covalent Adaptable Networks

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