Volume Phase Transition in Gels: Its Discovery and Development

Dušek, Karel; Dušková‐Smrčková, Miroslava

doi:10.3390/gels6030022

Cited by 27 publications

(21 citation statements)

References 78 publications

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“…This volume change may occur gradually (continuous), or drastically (discontinuous) as a first-order volume phase transition. The discontinuous volume phase transition in gels from swollen to collapsed states, similar to the coil-to-globule transition of a single polymer chain, was first predicted in 1968 by Dusek and Paterson [ 7 , 12 ]. They showed that, under certain conditions, the chemical potential of the solvent in a gel passes through two extremes when plotted against the polymer volume fraction

(Equation (1a,b)).…”

Section: Swelling-deswelling Transition Of Stimuli Responsive Hydrogelsmentioning

confidence: 89%

Re-Entrant Conformation Transition in Hydrogels

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2021

Gels

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Hydrogels are attractive materials not only for their tremendous applications but also for theoretical studies as they provide macroscopic monitoring of the conformation change of polymer chains. The pioneering theoretical work of Dusek predicting the discontinuous volume phase transition in gels followed by the experimental observation of Tanaka opened up a new area, called smart hydrogels, in the gel science. Many ionic hydrogels exhibit a discontinuous volume phase transition due to the change of the polymer–solvent interaction parameter χ depending on the external stimuli such as temperature, pH, composition of the solvent, etc. The observation of a discontinuous volume phase transition in nonionic hydrogels or organogels is still a challenging task as it requires a polymer–solvent system with a strong polymer concentration dependent χ parameter. Such an observation may open up the use of organogels as smart and hydrophobic soft materials. The re-entrant phenomenon first observed by Tanaka is another characteristic of stimuli responsive hydrogels in which they are frustrated between the swollen and collapsed states in a given solvent mixture. Thus, the hydrogel first collapses and then reswells if an environmental parameter is continuously increased. The re-entrant phenomenon of hydrogels in water–cosolvent mixtures is due to the competitive hydrogen-bonding and hydrophobic interactions leading to flow-in and flow-out of the cosolvent molecules through the hydrogel moving boundary as the composition of the solvent mixture is varied. The experimental results reviewed here show that a re-entrant conformation transition in hydrogels requires a hydrophobically modified hydrophilic network, and a moderate hydrogen-bonding cosolvent having competitive attractions with water and polymer. The re-entrant phenomenon may widen the applications of the hydrogels in mechanochemical transducers, switches, memories, and sensors.

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(Equation (1a,b)).…”

Section: Swelling-deswelling Transition Of Stimuli Responsive Hydrogelsmentioning

confidence: 89%

Re-Entrant Conformation Transition in Hydrogels

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2021

Gels

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“…Polyelectrolyte gels can show a discontinuous volume phase transition (DVPT) stimulated by, e.g., pH, temperature, or solvent composition and exhibit high swelling ratios due to an additional ionic free energy contribution for good solvent conditions at low salt concentrations. − Polyelectrolyte tendomers (“tendolytes”) connected to a gel may show a similar behavior, but the nonlinear deformation behavior of tendomers alone will not cause a DVPT. Since the elastic free energy in the nonlinear regime differs qualitatively from ideal rubber elasticity, the corresponding changes for the free energy of the tendolyte gel may shift, enhance or even suppress a DVPT.…”

Section: Network Preparation For the Nonlinear Regimementioning

confidence: 99%

Swelling of Tendomer Gels

2021

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We propose a new type of polymer gels made of tendomers as elastic elements. Tendomers are a pair of rotaxanes with a specific nonlinear response and an almost step-like softening transition by increasing their extension. We consider the swelling equilibrium of tendomer gels in good solvents based on a Flory− Huggins type of approach. Using the exact solution for the single tendomer force−extension relation, we calculate the swelling equilibrium of the gels numerically. For the limiting cases of the linear and nonlinear elastic regimes of the tendomer strands, we derive analytic solutions for the equilibrium degree of swelling as a function of the system parameters. We show that the resulting tendomer networks can swell much more than conventional gels and that the preparation conditions can be tuned such that the gels swell predominantly in a linear or a nonlinear response regime. Tendomer gels are also a prototype of a super-soft and practically entanglement-free gel since at preparation state, the tendomers consist mainly of long elastically inactive tails that act as a reservoir of chain segments upon swelling or deformation. This results in a c*-like state at swelling equilibrium for appropriate preparation and swelling conditions. Besides swelling in a good solvent, we also consider the swelling equilibrium of charged tendomer gels. Specific preparation conditions are taken into account in terms of a prestrain coefficient of the network. Monte-Carlo simulations and numerical calculations are performed to test the theoretical predictions. Finally, we discuss a possible route for the synthesis of tendomer gels.

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“…Of relevance to iTLS efforts, most hydrogel preparations can be injectable or transplantable depending on the timing and chemistries of the crosslinking steps, and can be formulated in large injection/implantation volumes or in micro or even nanoscale particle preparations (104). Because of their large capacity to hold aqueous solution, many hydrogel preparation methodologies are widely compatible with cell culture conditions so long as the chemistries required for crosslinking do not stray from physiologic pH, temperature, salinity, and other cell culture ranges (105)(106)(107). For this reason, crosslinking chemistries that utilize mild temperature or pH changes such as warming from 4°C to 37°C or changing from a slightly acidic solution to slightly basic are ideal for injectable preparations, as such hydrogels would crosslink after injection into living recipients (105,107).…”

Section: Hydrogelsmentioning

confidence: 99%

Inducible Tertiary Lymphoid Structures: Promise and Challenges for Translating a New Class of Immunotherapy

et al. 2021

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Tertiary lymphoid structures (TLS) are ectopically formed aggregates of organized lymphocytes and antigen-presenting cells that occur in solid tissues as part of a chronic inflammation response. Sharing structural and functional characteristics with conventional secondary lymphoid organs (SLO) including discrete T cell zones, B cell zones, marginal zones with antigen presenting cells, reticular stromal networks, and high endothelial venues (HEV), TLS are prominent centers of antigen presentation and adaptive immune activation within the periphery. TLS share many signaling axes and leukocyte recruitment schemes with SLO regarding their formation and function. In cancer, their presence confers positive prognostic value across a wide spectrum of indications, spurring interest in their artificial induction as either a new form of immunotherapy, or as a means to augment other cell or immunotherapies. Here, we review approaches for inducible (iTLS) that utilize chemokines, inflammatory factors, or cellular analogues vital to TLS formation and that often mirror conventional SLO organogenesis. This review also addresses biomaterials that have been or might be suitable for iTLS, and discusses remaining challenges facing iTLS manufacturing approaches for clinical translation.

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Volume Phase Transition in Gels: Its Discovery and Development

Cited by 27 publications

References 78 publications

Re-Entrant Conformation Transition in Hydrogels

Re-Entrant Conformation Transition in Hydrogels

Swelling of Tendomer Gels

Inducible Tertiary Lymphoid Structures: Promise and Challenges for Translating a New Class of Immunotherapy

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