Deswelling Kinetics Research Articles

Deswelling Mechanisms of PNIPAM Grafted in Nanochannels: A Molecular Dynamics Simulation Study.

Porous thermosensitive hydrogels exhibit a more flexible strategy for freshwater capture compared to conventional hydrogels. This study employs molecular dynamics (MD) simulation to investigate the deswelling behavior of poly(N-isopropylacrylamide) (PNIPAM) grafted within the nanochannel, aiming to elucidate the deswelling elimination process at various temperatures. Notably, a distinct phase separation is observed at specific temperatures above the lower solution temperature (LCST). Furthermore, this study takes the effect of heat flux into account, wherein distinct heat fluxes lead to varying levels of phase separation between water and the polymer. Specifically, the number of hydrogen bonds, volume of polymer chains, and density distribution of water molecules are statistically analyzed to reveal the mechanism of phase separation in a thermosensitive hydrogel. These findings provide insight into the accelerated deswelling kinetics of the PNIPAM polymer chain, which has guiding significance for the field of water harvesting by the enhancement of the water release capacity in thermosensitive hydrogels.

UV-Vis spectroscopy in the characterization and applications of smart microgels and metal nanoparticle-decorated smart microgels: a critical review.

Smart microgels (SMGs) and metal nanoparticles (MNPs)-decorated smart microgels have garnered significant attention because of their responsive behavior. Both SMGs and their hybrids are extensively used in adsorption, drug delivery, and catalysis, which can be characterized with expensive instruments. UV-Vis spectroscopy is a technique that can easily monitor these processes, and it can also identify the presence of noble metal nanoparticles, like Ag and Au, in smart microgels with the help of the surface plasmon resonance wavelength of these metals. This technique is widely employed to determine the size and shape of MNPs present in microgels. Additionally, UV-Vis spectroscopy enables the investigation of optical behaviors of noble metal nanoparticles under various stimuli. Time-dependent UV-Vis spectroscopy can monitor the kinetics of swelling and deswelling in MGs and HMGs. It also facilitates the study of metal nanoparticle growth within polymer networks or the growth of polymer networks around metal nanoparticle cores. Furthermore, UV-Vis spectroscopy can be used to explore numerous applications of microgels and hybrid substances in photonics, sensing, catalysis, and adsorption. This tutorial review highlights the use of UV-Vis spectroscopy in the characterization and applications of both smart microgels and their hybrids in adsorption and catalysis, considering the recent research advancements in these fields.

Deswelling kinetics in CorneaJet of organ cultured human corneas

AbstractPurposeThe deswelling of a corneal graft at the end of storage in the eye bank is essential before perforating or deep anterior lamellar keratoplasty to allow good donor/recipient congruence and to accelerate visual recovery. In France, CorneaJet (Eurobio, France) containing 5% Dextran T500 is the most commonly used medium, but its deswelling kinetics is not referenced and the duration of 48 or 72 hr is chosen purely by habit while the increase in endothelial toxicity over time is documented.AimTo determine the corneal deswelling kinetics in CorneaJet.Methods12 corneas discarded by our eye bank were used. They had an endothelial cell density at reception (day 2 to day 4) of 1713 ± 389 cell/mm2 (mean ± SD). All had been stored in organoculture in CorneaMax medium at 31°C for at least 1 week. The corneas were immersed in 50 ml vials of CorneaJet (same batch) and were stored at 31°C. Central corneal thickness (CCT in µm) and central corneal volume (on an 8mm disc, CCV8 in mm3) were measured by optical coherence tomography (OCT, Casia I, Tomey, Japan). Transparency was evaluated on a prototype measuring contrast transmission (relative scale in %). Measurements were performed before immersion in CorneaJet and repeated at hour (H)3, H6, H9, H12, H18, H24, H30, H36 and H48.ResultsAll data were expressed as mean ± SD respectively at the different times. CCT: 1284 ± 249; 1031 ± 233; 897 ± 22; 773 ± 160; 741 ± 123; 673 ± 75; 626 ± 27; 638 ± 41; 645 ± 49; 652 ± 55. CCV8: 73 ± 9; 61 ± 9; 53 ± 9; 47 ± 8; 44 ± 6; 40 ± 4; 38 ± 3; 37 ± 3; 37 ± 3 and 37 ± 3. Transparency: 13 ± 4; 19 ± 5; 24 ± 6; 29 ± 6; 33 ± 7; 40 ± 7 41 ± 7; 44 ± 9; 45 ± 8 and 44 ± 11.ConclusionsCorneal deswelling in CorneaJet is rapid during the first 12 hr and reaches a plateau at 20 hr. After 20 hr, transparency and thickness are ideal for surgery.

Fabrication and characterization of a starch-based superabsorbent hydrogel composite reinforced with cellulose nanocrystals from potato peel waste

A semi-interpenetrating polymer network (semi-IPN) superabsorbent hydrogel composite based on starch (St)-graft-poly(acrylic acid (AA)-co-acrylamide (AM))/polyvinyl alcohol (PVA) and cellulose nanocrystals (CNC) was synthesized using free radical aqueous polymerization method. Cellulose nanocrystals were extracted from potato peel waste using alkali treatment followed by acid hydrolysis. FTIR analysis affirmed the grafting reaction of acrylate-based monomers onto starch backbone as well as composite formation. The structural and morphological features of the hydrogels were examined by XRD, SEM, and TEM techniques. The hydrogel composite exhibited higher equilibrium swelling ratio (921.8 g/g) compared with the neat hydrogel (772.4 g/g). The swelling kinetics of the prepared hydrogels had high compliance with the first order swelling kinetic model. The diffusion coefficient value of the hydrogel composite was higher than that of the neat hydrogel, revealing that the incorporation of cellulose nanocrystals into the hydrogel matrix had resulted in faster penetration of water molecules into the polymeric network. The examination of the viscoelastic behavior of hydrogel samples by rheological tests revealed that the elastic behavior of the samples prevails over their viscous behavior. Moreover, the storage modulus of hydrogel composite was higher than that of the neat hydrogel over the entire frequency range which shows the stiffer network of the hydrogel composite. The hydrogel composite exhibited high saline absorbency under load, good deswelling kinetics in different saline solutions, desirable swelling/drying capability, and acceptable pH-dependent swelling reversibility which make it a potential candidate for agricultural and horticultural applications.

Adsorptive removal of alcohols from aqueous solutions by N-tertiary-butylacrylamide (NtBA) and acrylic acid co-polymer gel

A co-polymer gel of N-tert-butylacrylamide and acrylic acid was swelled in alcohols differing in its dipole moment and H-bonding interaction parameter so as to inspect the relative affinities of the gel towards alcohols. The gel swelled 900% in ethanol, 1200% in propanol and 750% in butanol. The extent of swelling can be used as a guide for preferential removal of particular alcohol from its mixture. Studies on adsorption isotherm using different isotherm equations helped in deciding the mechanism of adsorption of ethyl alcohol. The swelling and de-swelling kinetics of the gel in ethanol, propanol, and butanol (at low concentration of 5 g/l each) followed mostly Fickian type diffusions for the processes of absorption and desorption. The scope of repeated use of the gel for the alcohol recovery was investigated and every time approximately 98% alcohol could was found to be recovered. The honeycomb morphology of the gel was accountable for such swelling of the gel.

Tuning of thermoresponsive pNIPAAm hydrogels for the topical retention of controlled release ocular therapeutics.

Low patient compliance and poor bioavailability of ophthalmic medications are the main limitations of topical eye drops. A potential solution to these disadvantages could be provided by thermoresponsive hydrogels, which could be used as the basis for a gelling eye drop for long-term release of therapeutics. We previously reported such a system capable of being retained in the lower fornix of rabbits, continuously releasing an anti-glaucoma drug for one month. Here, we sought to improve the properties of the existing gels as most relevant to patient use without altering the drug release profile. Specifically, we optimized the sol-to-gel transition temperature and de-swelling kinetics of pNIPAAm gels to avoid risk of the gelled drop reverting to liquid during cold or windy weather, and ensure quick gelation upon administration. A reduction of the gel LCST, faster gelation kinetics, and suitable viscosity for the administration as an eye drop were successfully achieved through modification of the poly(ethylene glycol) content in the water phase and its molecular weight. Our data suggest that drug release is not affected by these changes, with representative drug concentration profiles of the previous and new formulations demonstrating comparable anti-glaucoma release kinetics.

The OBSERV platform (Ophthalmic Bioreactor Specialized in Experimental Research & Valorisation): Kinetics of human cornea swelling and deswelling in the bioreactor as a function of IOP and endothelial status

The OBSERV platform (Ophthalmic Bioreactor Specialized in Experimental Research & Valorisation): Kinetics of human cornea swelling and deswelling in the bioreactor as a function of IOP and endothelial status

3D Cocontinuous Composites of Hydrophilic and Hydrophobic Soft Materials: High Modulus and Fast Actuation Time.

Hydrogels in nature seldom form a single phase, more often forming structured phases with other soft phases, allowing nature to develop responsive and adaptive strategies. Based on knowledge of how hydrogels are utilized in nature, we developed novel 3D cocontinuous composites from soft materials with extremely different properties, a hydrogel and a silicone. These were successfully prepared by infiltrating liquid polydimethylsiloxane (PDMS) into poly(N-isopropylacrylamide) (PNIPAm) frameworks of aligned pores prepared by directional melt crystallization. The composites had outstanding modulus and swelling ratio compared to other mechanically strong hydrogels. More interestingly, the deswelling kinetics were dramatically accelerated (by a factor of 1000), possibly due to the aligned microchannels and the hydrophobic nature of PDMS. As a result, an actuator movement mimicking flowering could be completed in less than 20 s. This novel and versatile cocontinuous composite strategy could overcome the current limitations of soft materials.

Rapid Deswelling of Porous Poly[2-(N-morpholino)ethyl methacrylate] Hydrogel and Controlled Release of Ibuprofen

ABSTRACTA novel, rapidly responsive, cross-linkedpoly[(2-N morpholino)ethyl methacrylate] (PMEMA) hydrogel was synthesized through free radical polymerization at room temperature. The highly swellable PMEMA gel displayed rapid deswelling kinetics in response to salt and temperature changes in its environment. During the deswelling test the hydrogel lost 75% of its water within 4 min in response to the salt effect, while it lost only 30% of its water in response to a temperature change within the same interval. Scanning electron microscopy revealed that the PMEMA gel has numerous open pore channels allowing rapid diffusion of water or water-soluble molecules from the gel matrix. Such a rapid response to environmental stimuli is promising for biomedical applications. Therefore, the designed gel was used as a potential drug carrier using water insoluble Ibuprofen (IBU) as a test drug. The results suggest that the PMEMA hydrogel would be beneficial for achieving a slow/controlled release of water-insoluble drugs.

Comparison the properties of PVA/Na+‐MMT nanocomposite hydrogels prepared by physical and physicochemical crosslinking

A novel physicochemical crosslinked nanocomposite hydrogel based on polyvinyl alcohol (PVA) and natural Na‐montmorillonite (Na+‐MMT) was synthesized by chemical crosslinking of nanocomposite hydrogel followed by a freezing‐thawing process. The effects of physical crosslinking, as well as physicochemical crosslinking, on the structure, morphology, and properties (thermal, mechanical, swelling, and deswelling) of nanocomposite hydrogels were investigated and compared with each other. The structure and morphology of nanocomposites were studied by Fourier transform infrared, X‐ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy techniques. The thermal and mechanical properties of nanocomposites that were affected by physical and physicochemical crosslinking were evaluated by thermogravimetric analysis, differential scanning calorimeter, dynamic mechanical analysis, hardness test, and Water vapor transmission rate (WVTR) experiments. The results showed that the physicochemical crosslinking of a PVA nanocomposite leads to a reduction in crystallinity and melting temperature, as well as an increase in the Hardness and WVTR compared to a physically crosslinked PVA nanocomposite hydrogel. The swelling and deswelling experiments were performed using a gravimetric method, and it was shown that controlled crosslinking of PVA nanocomposite hydrogel with glutaraldehyde causes the swelling ratio to increase and the cumulative amount of water loss to decrease. The swelling (sorption) and deswelling (desorption) kinetics data for physically and physicochemical crosslinking of nanocomposite hydrogels were fitted with a fickian model. It is concluded that through control crosslinking of PVA nanocomposite can lead to a hydrogel with higher swelling capacity than that is in conventional PVA nanocomposite hydrogel. POLYM. COMPOS., 37:897–906, 2016. © 2014 Society of Plastics Engineers

Preparation and characterization of a thermal responsive of poly(N-isopropylacrylamide)/chitosan/gelatin hydrogels

Synthesis of interpenetrating polymer network (IPN) of chitosan-gelatin (Cs-Ge) (as a primary network) and N-isopropylacrylamide (NIPAAm) monomer (as the secondary network) was carried out with different ratio. Its structure was characterized by FT-IR, which indicated that the IPN was formed. The memberanes were studied by swelling, weight loss with time. The interior morphology of the IPN hydrogels was revealed by scanning electron microscopy (SEM); the IPN hydrogels showed a interpenetrated network of NIPAAm/chitosan has layers with more minute stoma and canals compared to interpenetrated network of NIPAAm/gelatin. Lower critical solution temperature (LCST), equilibrium swelling ratio (ESR) and deswelling kinetics were measured. The DSC results noticed that LCST of IPN hydrogels with different ratio of Cs/Ge/PNIPAAm are around <TEX>$33{\pm}2^{\circ}C$</TEX>. The ESR obtained results showed that with a ratio of Cs/Ge/NIPAAm: 1/1/6, the swelling ratio increased drastically from room temperature to <TEX>$36^{\circ}C$</TEX> but with a ratio of Cs/Ge/PNIPAAm: 1/3/6, decrease significantly at the same condition. Therefore the hydrogels have been changed from a hydrophilic structure to a hydrophobic structure. Furthermore with an increase in temperature from room to the LCST, the ESR of IPN with higher concentration of (PNIPAAm) and (Ge) decreases but de-swelling kinetics of them are faster. Due to the suitable and different kinetics of de-swelling and the equilibrium swelling ratio (ESR) in various proportions, and because of the morphology inside the mass which confirms other tests, these hydrogels are very appropriate as a smart thermosensitive hydrogels with rapid response.

CdS Quantum Dots Doped Tuning of Deswelling Kinetics of Thermoresponsive Hydrogels Based on Poly(2-(2-methoxyethoxy)ethyl methacrylate)

Thermoresponsive poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMEO2MA) based hybrid nanocomposite hydrogels (NCH) were synthesized by dispersing preformed cadmium sulfide (CdS) quantum dots (QDs) in the reaction mixture followed by polymerization via reversible addition-fragmentation chain transfer (RAFT) technique. High doping capacity and negligible QDs leakage were observed for hydrophilic QDs doped hydrogels (hpl-NCH) due to H-bonding interactions between QDs and pendant groups of hydrogel network. The hpl-NCH networks showed improved structural/orientational order and swelling ratios with increasing doping concentration compared to the organic hydrogel (OH). Opposite trends were observed for bulk-CdS (NCH-bulk) and 1-dodecanethiol capped CdS (NCH-DDT) doped hydrogels. Swelling induced linear retardance and quenching of photoluminescence (PL) intensity for hydrogels were exploited to study the deswelling kinetics respectively by Mueller matrix polarimetry and solid state fluorimetry, which were further corroborated with gravimetric analysis. For all the NCH, deswelling process significantly decreased with increasing temperature, which followed the order: 30 > 45 > 60 °C. Slower deswelling was observed for NCH-bulk and hpl-NCH compared to the OH, and also with increase in doping concentration due to the formation of skin layer. However, NCH-DDT exhibited accelerated deswelling process and the order was reversed with respect to doping concentration due to DDT mediated enhanced hydrophobic aggregation and water leakage channels created by long hydrophobic free-mobile nature of QDs surface tethered DDT molecules. The presented methodology provides tunable deswelling of PMEO2MA based hydrogels by doping with hydrophilically/hydrophobically modified CdS QDs.

Swelling-Induced Optical Anisotropy of Thermoresponsive Hydrogels Based on Poly(2-(2-methoxyethoxy)ethyl methacrylate): Deswelling Kinetics Probed by Quantitative Mueller Matrix Polarimetry

Thermodynamically favored polymer-water interactions below the lower critical solution temperature (LCST) caused swelling-induced optical anisotropy (linear retardance) of thermoresponsive hydrogels based on poly(2-(2-methoxyethoxy)ethyl methacrylate). This was exploited to study the macroscopic deswelling kinetics quantitatively by a generalized polarimetry analysis method, based on measurement of the Mueller matrix and its subsequent inverse analysis via the polar decomposition approach. The derived medium polarization parameters, namely, linear retardance (δ), diattenuation (d), and depolarization coefficient (Δ), of the hydrogels showed interesting differences between the gels prepared by conventional free radical polymerization (FRP) and reversible addition-fragmentation chain transfer polymerization (RAFT) and also between dry and swollen state. The effect of temperature, cross-linking density, and polymerization technique employed to synthesize hydrogel on deswelling kinetics was systematically studied via conventional gravimetry and corroborated further with the corresponding Mueller matrix derived quantitative polarimetry characteristics (δ, d, and Δ). The RAFT gels exhibited higher swelling ratio and swelling-induced optical anisotropy compared to FRP gels and also deswelled faster at 30 °C. On the contrary, at 45 °C, deswelling was significantly retarded for the RAFT gels due to formation of a skin layer, which was confirmed and quantified via the enhanced diattenuation and depolarization parameters.

Solvent exchange kinetics in poly(N-isopropylacrylamide) microgel-based etalons

Poly (N-isopropylacrylamide)-co-acrylic acid (pNIPAm-co-AAc) microgel-based etalons are constructed by depositing thin Au layers (mirrors) on either side of a planar microgel layer. When immersed in water, the microgel layer swells and the etalon exhibits visual color. The thermoresponsivity of the pNIPAm-based microgels allows the Au mirror spacing, and hence the device color, to be dynamically modulated. Necessarily, when the mirror spacing is modulated solvent in the microgel layer must be expelled to the surroundings. Previously, we determined that the etalon deswelling kinetics depended critically on the thickness of the Au layer covering the microgels. Here, we report on solvent exchange kinetics. We found that the time required for solvent entry into the microgel layer is much longer than solvent exit. In addition, the rate was found to again depend critically on the thickness of the Au layer covering the microgel layer; thicker Au layers corresponded to slower solvent exchange kinetics.

Dually Responsive Multi-Network Hydrogel of N-Isopropylacrylamide Copolymeric Microgels Embedded in Poly(vinyl alcohol)

To improve the performance of traditional hydrogels, dually responsive multi-network hydrogel was designed and fabricated in two steps. Firstly, temperature-and pH-responsive copolymeric microgel of N-isopropylacrylamide, methacrylic acid and polyethyleneglycol methacrylate were prepared via precipitation polymerization in poly (vinyl alcohol) (PVA) aqueous solution. Then glutaraldehyde was added to the microgel dispersion to build crosslinks among microgels and PVA, producing multi-network hydrogel with thermo-and pH-sensitivity. The morphology of the microgel and hydrogel was characterized by electron microscope technique. Swelling and deswelling behaviors show that the obtained hydrogels exhibit good temperature-and pH-sensitivity. The hydrogel shows rapid deswelling kinetics and approaches deswelling equilibrium in ~30min.

Deswelling Kinetics of Color Tunable Poly(N-Isopropylacrylamide) Microgel-Based Etalons

Poly(N-isopropylacrylamide) (pNIPAm) microgel-based etalons are optical materials fabricated by depositing a monolithic layer of microgels on a semitransparent Au film adhered to a glass coverslip, followed by the deposition of a second semitransparent Au layer over the microgel layer (overlayer). These materials exhibit characteristic colors and multipeak reflectance spectra, both of which depend on the distance between the Au surfaces (mediated by the microgel diameter) and the refractive index of the microgel layer. In this submission, the deswelling kinetics of pNIPAm microgel-based etalons are investigated by inducing microgel deswelling through exposure to a 30% methanol/H(2)O solution. Exposed to this solvent system, the transition temperature of the microgels is lowered to a temperature below the experimental temperature and the microgels comprising the etalon collapse. This collapse induces an etalon color change, which is observed as a blue shift in the reflectance spectrum. The kinetics of deswelling were shown to be strongly dependent on the thickness of the Au overlayer, e.g., thicker overlayers slow the solvent exchange and the resultant deswelling kinetics. Additionally, for thicker overlayers, the rate of deswelling increases with decreasing etalon size. Taken together, these results suggest that the kinetics depend strongly on the ability of the solvent to exchange from/to the microgel layer. For example, if the Au overlayer is thin, more solvent can exchange through the overlayer in a given amount of time compared to an etalon composed of a thick overlayer. Likewise, etalons of smaller dimensions have faster deswelling kinetics due to the shorter distance the solvent needs to travel laterally through the microgel layer to exchange. The results from this study are of fundamental importance but will be used to develop sensors with fast response times for point-of-care diagnostics.

Thermo- and pH-sensitive behavior of hydrogels based on oligo (ethylene glycol) methacrylates and acrylic acid

Novel dual stimuli-responsive hydrogels were prepared by free-radical polymerization of 2-(2-methoxyethoxy) ethyl methacrylate (MEO2MA) and oligo (ethylene glycol) methacrylate (OEGMA), as thermosensitive monomers, and acrylic acid (AAc), as a pH-sensitive monomer. Due to the thermosensitive monomers introduced in the macromolecular network, the synthesized materials possessed tunable thermal behavior. In addition, as well as by introducing in the polymerization feed pH-sensitive monomer AAc, the equilibrium swelling properties of the hydrogels can be tuned by three comonomers. Moreover, the de-swelling kinetics was studied by changing temperature and/or pH, and they could be well described with a first-order kinetics equation. Especially, the faster shrinking rates of hydrogels were observed when the simultaneous temperature and pH stimuli changed from pH 8/18 to pH 2/55 °C because of the cooperative thermo-/pH responses. The prepared dual temperature-/pH-sensitive PMOA hydrogels as a new material candidate may provide significant valuable information for various potential applications.

Comparison of Thermoresponsive Deswelling Kinetics of Poly(oligo(ethylene oxide) methacrylate)-Based Thermoresponsive Hydrogels Prepared by “Graft-from” ATRP

Cross-linked thermoresponsive poly(2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene oxide) methyl ether methacrylate-co-2-hydroxyethyl methacrylate-co-ethylene glycol dimethacrylate) hydrogels (poly(MEO2MA−OEOMA−HEMA hydrogels) were prepared by atom transfer radical polymerization (ATRP). The hydroxyl groups in the formed gel networks were transformed to ATRP initiating sites containing 2-bromoisobutyrate groups, and the modified gels were used as macroinitiators for “graft-from” ATRP of MEO2MA and OEOMA. The thermoresponsive properties of the resulting comb-type grafted hydrogels were compared to their unmodified precursor hydrogels with respect to the transition temperatures and deswelling rates. The thermoresponsive properties could be customized by changing the grafting density, grafted chain length, and the chain composition. Furthermore, the deswelling kinetics of the prepared hydrogels were quantitatively analyzed by exponential fitting of water retention with time. This analysis demonstrate...

Synthesis, Swelling and Drug-Release Behaviour of a Poly(N,N-diethylacrylamide-co-(2-dimethylamino) ethyl methacrylate) Hydrogel

In this study, poly(N,N-diethylacrylamide-co-(2-dimethylamino) ethyl methacrylate) (poly(DEA-co-DMAEMA)) hydrogels were synthesized by changing the initial DEA/DMAEMA mol ratio. The hydrogels were characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). In comparison with the PDEA hydrogel, the equilibrium swelling ratio (ESR) and lower critical solution temperature (LCST) of the hydrogels increase with the increase of DMAEMA content in the feed. The deswelling and reswelling kinetics and cytotoxicity of the different composition ratios of DEA to DMAEMA in the co-polymerized hydrogels were also investigated in detail. The absorption and release behaviour of the model drug, bovine serum albumin, were found to be dependent on hydrogel composition and environment temperature, which suggests that these materials have potential application as intelligent drug carriers.

A dual mode interpretation of the kinetics of penetrant-induced swelling and deswelling in a glassy polymer

In this study, a unified dual mode description of penetrant sorption and desorption kinetics in a glassy polymer was extended to the study of the kinetics of penetrant-induced swelling and deswelling below the glass transition concentration. The swelling of cellulose acetate (CA) induced by the sorption of vapor phase acetonitrile, and the subssuent deswelling during desorption, was measured using time-resolved FTIR-ATR (Fourier Transform Infrared-Attenuated Total Reflectance) spectroscopy. Equilibrium swelling as a function of penetrant activity from the spectroscopic measurements was confirmed with conventional length elongation measurements (dilatometry). From equilibrium measurements that traversed the glass transition concentration, the partial molar volume both below and above the transition was determined. Using the partial molar volume obtained above the glass transition and assuming that only the dissolved population contributes to dilation, the swelling kinetics can be predicted from the dual mode framework presented here. However, the deswelling kinetics cannot be predicted, suggesting that a fraction of the holes formed upon sorption in the unified model must collapse during contraction of the polymer upon desorption.