Calorimetric Glass Transition Research Articles

Structure-Glass Transition Relationships in Non-Isocyanate Polyhydroxyurethanes.

The molecular dynamics, with an emphasis on the calorimetric and dynamic glass transitions, of non-isocyanate polyhydroxyurethanes (PHUs) produced by the equimolar polyaddition of polyether-based dicyclic carbonates (P-CCs) and various short diamines was studied. The diamine component consisted of a short aliphatic diamine (1,4-diaminobutane, DAB) and a more complex 'characteristic' diamine. The study was conducted to investigate (i) the chemical structure of the characteristic amine, (ii) its molar ratio, and (iii) the structure and molar mass of the P-CC. Infrared spectroscopy, differential scanning calorimetry, and broadband dielectric spectroscopy were employed. The P-CC, constituting the bulk of the systems, was the most crucial component for the glass transition. The characteristic amine influenced the glass transition as a result of its bulky structure, but also presumably as a result of the introduction of free volume and the formation of hydrogen bonds. The dynamic glass transition (α relaxation) trace in the Arrhenius plots showed a subtle change at a certain temperature that merits further study in the future. The charge mobility was fully coupled with the molecular mobility, as evidenced by dc conductivity being directly proportional to the characteristic frequency of α relaxation. The fluctuation in carbonyl units (β relaxation) was mildly affected by changes in their immediate environment.

A pressure and entropy criterion for glass transition decoupling in high-entropy metallic glasses

Decoupling between calorimetric and dynamical glass transitions has been observed in high-entropy metallic glasses (HEMGs) owing to their complex entropy effects. Pressure is another versatile thermodynamic variable that can be used to control the properties of metallic glasses (MGs) owing to the reduced interatomic distances. However, how can it affect such anomalous decoupling behavior in HEMGs remains unclear. Here, molecular dynamics simulations are performed to investigate the influence of pressure on the decoupling behavior in several prototypical MGs and HEMGs. We find that pressure can enhance the sluggish atomic diffusion and depress structural α-relaxation, thus promoting the decoupling in HEMGs, even with less atomic size mismatch. Finally, incorporating pressure and configurational and mismatch entropies, we propose a general criterion based on an explainable machine-learning method to quantitatively classify MG's decoupling or not. These findings refine our understanding of glass transitions and suggest an avenue for manipulating decoupling behaviors in HEMGs.

Molecular mobility and thermal transitions study in renewable PLA-polyols star-like copolymers

The molecular dynamics mapping in poly(lactic acid) (PLA)-based star-like copolymers is performed herein, employing dielectric spectroscopy techniques supplemented by calorimetry and other structure characterization methods. Next to the neat linear PLA, three star-like copolymers, with 3, 4 and 5 branches were synthesized via ring opening polymerization at the presence of, respectively, glycerol, pentaerythritol and sorbitol (initiators). When increasing the branch number, consequently, the overall molar mass drops, from 55 kg/mol (neat PLA) to 17k (PLA@glycerol), 25k (PLA@pentaerythritol), and 14k (PLA@sorbitol) and, thus, the branch length decreases to ∼6k, ∼6k, and ∼3 k g/mol in the stars. The latter leads to faster segmental mobility, documented by the accelerated α relaxation and the drop in the calorimetric and dielectric glass transition temperatures. Simultaneously, the cooperativity (chains’ fragility) drops. Together these results suggest possibly the increase in free volume, a factor that can potentially favour the physical biodegradability. Next to the segmental dynamics, the local beta relaxation is recorded to have a mild dependence on the type of star (mainly decelerates), while the rare case of Normal Mode relaxation is recorded here only in the stars, providing additional support for the quite short branches. The overall data suggest the co-implementation of two antagonistic effects on mobility, i.e., the chain length changes in parallel to the constraints imposed by the star-like structure. Moreover, the in general low crystallizability of linear PLA further drops in the stars in terms of both suppressed crystalline fraction and nucleation, as well as lower quality of crystals. The materials exhibit single thermal transitions, indicating a homogeneous character, whereas a variety of semicrystalline morphologies can be achieved via both the composition and the thermal treatment. This provides a tool for tuning various properties and, consequently, the manipulation of the macroscopic performance.

Effects of Segment Length and Crosslinking via POSS on the Calorimetric and Dynamic Glass Transition of Polyurethanes with Aliphatic Hard Segments.

The glass transition in polyurethanes is a complicated phenomenon governed by a multitude of factors, including the microphase separation, which in turn depends strongly on the molar mass of the hard and soft segments, as well as the presence of additives. In this work, we study the effects of the segments' length on the microphase separation and consequently on the calorimetric and dynamic glass transition of a polyurethane with aliphatic, "flexible" hard segments. It is found that the dependence of the calorimetric glass transition follows the same principles as those in systems with aromatic hard segments. Strikingly, however, the dynamic glass transition, as studied by dielectric spectroscopy, shows a slowing down of its dynamics despite a decrease in Tg. This discrepancy is discussed in terms of the strong dielectric response of the flexible segments, especially those close to the interface between the hard domains and soft phase, as opposed to a weak thermal one. In addition, polyhedral oligomeric silsesquioxanes (POSS) are introduced in the soft phase of the three matrices as crosslinking centres. This modification has no visible effect on the calorimetric glass transition; nevertheless, it affects the microphase separation and the dielectric response in a non-monotonic manner.

A Second Glass Transition Observed in Single-Component Homogeneous Liquids Due to Intramolecular Vitrification.

On supercooling a liquid, the viscosity rises rapidly until at the glass transition it vitrifies into an amorphous solid accompanied by a steep drop in the heat capacity. Therefore, a pure homogeneous liquid is not expected to display more than one glass transition. Here we show that a family of single-component homogeneous molecular liquids, titanium tetraalkoxides, exhibit two calorimetric glass transitions of comparable magnitude, one of which is the conventional glass transition associated with dynamic arrest of the bulk liquid properties, while the other is associated with the freezing out of intramolecular degrees of freedom. Such intramolecular vitrification is likely to be found in molecules in which low-frequency terahertz intramolecular motion is coupled to the surrounding liquid. These results imply that intramolecular barrier-crossing processes, typically associated with chemical reactivity, do not necessarily follow the Arrhenius law but may freeze out at a finite temperature.

AFM dilatometry measurements on ultra‐stable fluoropolymer glasses: Further evidence of extreme fictive temperature reduction

AbstractUltra‐stable amorphous fluoropolymers glasses were created using vacuum pyrolysis deposition (VPD). Glass films with thickness ranging from 90 to 160 nm were grown at a substrate temperature of 0.86 Tg, where Tg is the glass transition temperature of the virgin polymer and is in units of K. Atomic force microscope (AFM) dilatometry measurements were conducted to investigate density behavior of the ultra‐stable glasses. Thickness measurements were made in stepwise fashion over a range of temperatures from ambient to above the Tg. Results show that the intersections of the line for the equilibrium liquid and those for the rejuvenated and stable glasses identifying the fictive temperature Tf result in Tf, rejuvenated = 347.3 K and Tf, stable = 269.5 K, that is, nearly 80 K below the Tg of the rejuvenated material and well below the notional Kauzmann temperature as estimated from the Vogel‐Fultcher‐Tammann (VFT) analysis of the cooling rate dependence of the calorimetric glass transition temperature reported previously. The results corroborate the published calorimetric results on the same ultra‐stable fluoropolymer glasses that witnessed Tf reductions of up to 62.6 K below the Tg of the rejuvenated system. In addition, to demonstrate the versatility of the AFM dilatometry methodology for the thin film response, isothermal de‐aging experiments were carried out to illustrate the devitrification kinetics. We also carried out one of the Kovacs’ signature key experiments, the asymmetry of approach, to further illustrate the method.

Effects of atomic size mismatch on glass transition decoupling in high-entropy metallic glasses

The calorimetric and dynamical glass transitions are uncoupled in high entropy metallic glasses (HEMGs). That is, the thermal glass-transition or vitrification temperature (Tg) and α-relaxation temperature (Tα) are uncorrelated as a function of alloy stoichiometry. The underlying mechanism that gives rise to this is not understood, nor is the connection to atomic structure. Here, molecular dynamic (MD) simulations of different HEMG model systems are performed to investigate the glass transition behavior. In addition to the high configurational entropy of mixing (for an ideal solution), we show that the effect of mismatch entropy plays a critical role in decoupling vitrification kinetics/α-relaxation in HEMGs. Microscopically, the atomic size difference contributes significantly to the sluggishness of long-range diffusion and decreased dynamic heterogeneities. This gives rise to a depressed structural α-relaxation. More importantly, we find that HEMGs with the decoupling vitrification kinetics/α-relaxation can show unique mechanical performance, such as better radiation tolerance and higher resistance to shear banding. Our results provide insights into the high entropy effect of glassy metallic materials, and suggest a means for tuning properties of HEMGs.

Dissymmetric Triaryltriazines: Small Mass Columnar Glasses.

Columnar liquid crystals with very small molecular masses that form anisotropic glasses well above room temperature are obtained by mixed dissymmetric substitution of sym-triazine with ester-bearing phenyl and phenanthryl or tetrahelicenyl moieties. The combination of low molecular symmetry with configurational flexibility and short polar ester moieties stabilizes the mesophase over large temperature ranges and induces pronounced calorimetric glass transitions within the anisotropic fluid despite the smallness of the molecules. In contrast to more symmetrical homologs, no ester tails longer than ethyl are necessary to induce the liquid crystalline state, allowing for the near-absence of any insulating and weight-increasing alkyl periphery. Films drop-cast from solution show in all cases emission spectra that do not show significant change of fluorescence emission upon annealing, indicating that the columnar hexagonal mesoscopic order is obtained directly upon deposition from solution and is resistant to crystallization upon annealing.

Plasticization, Antiplasticization, and Fragility in Blends of Polyvinyl Butyral and Polyethylene Glycol Dimethyl Ether

AbstractBlends of polyvinyl butyral (PVB) and polyethylene glycol dimethyl ether (PEGDME) with low molecular weight (= 250 g mol−1) show two calorimetric (for PEGDME content higher than 11% by weight) and mechanical glass transitions. Their substantial changes in the relative content of the two components are explained by considering the self‐concentrations of both polymers determined by the connectivity of their own chains. Increasing content of PEGDME lower the glass transition temperature Tg of PVB (the component with the highest Tg) by about 100 K, also causing a progressive and significant increase of its fragility (following the Angell's strong/fragile liquids classification scheme). Strengthening of polymer blends is observed in the fully glassy region, quite below the Tg's of both the components, with the storage modulus E′ becoming more than a factor 2 higher than that of neat PVB. The progressive increase of E′, without any change of slope, points to structural homogeneity of blends determined by compatibility of components, as a result of interchain interactions activated by the polar groups of both polymers. The present results reveal that PEGDME plasticizes PVB when the blend is in the fully rubbery state while acting as an anti‐plasticizer in the fully glassy state.

Molecular Dynamics and Diffusion in Amorphous Solid Dispersions Containing Imidacloprid.

The main goal of this study is to develop an experimental toolbox to estimate the self-diffusion coefficient of active ingredients (AI) in single-phase amorphous solid dispersions (ASD) close to the glass transition of the mixture using dielectric spectroscopy (DS) and oscillatory rheology. The proposed methodology is tested for a model system containing the insecticide imidacloprid (IMI) and the copolymer copovidone (PVP/VA) prepared via hot-melt extrusion. For this purpose, reorientational and the viscoelastic structural (α-)relaxation time constants of hot-melt-extruded ASDs were obtained via DS and shear rheology, respectively. These were then utilized to extract the viscosity as well as the fragility index of the dispersions as input parameters to the fractional Stokes-Einstein (F-SE) relation. Furthermore, a modified version of Almond-West (AW) formalism, originally developed to describe charge diffusion in ionic conductors, was exercised on the present model system for the estimation of the AI diffusion coefficients based on shear modulus relaxation times. Our results revealed that, at the calorimetric glass-transition temperature (Tg), the self-diffusion coefficients of the AI in the compositional range from infinite dilution up to 60 wt % IMI content lied in the narrow range of 10-18-10-20 m2 s-1, while the viscosity values of the dispersions at Tg varied between 108 Pa s and 1010 Pa s. In addition, the phase diagram of the IMI-PVP/VA system was determined using the melting point depression method via differential scanning calorimetry (DSC), while mid-infrared (IR) spectroscopy was employed to investigate the intermolecular interactions within the solid dispersions. In this respect, the findings of a modest variation in melting point at different compositions stayed in agreement with the observations of weak hydrogen bonding interactions between the AI and the polymer. Moreover, IR spectroscopy showed the intermolecular IMI-IMI hydrogen bonding to have been considerably suppressed, as a result of the spatial separation of the AI molecules within the ASDs. In summary, this study provides experimental approaches to study diffusivity in ASDs using DS and oscillatory rheology, in addition to contributing to an enhanced understanding of the interactions and phase behavior in these systems.

Microscopic versus Macroscopic Glass Transitions and Relevant Length Scales in Mixtures of Industrial Interest.

We have combined X-ray diffraction, neutron diffraction with polarization analysis, small-angle neutron scattering (SANS), neutron elastic fixed window scans (EFWS), and differential scanning calorimetry (DSC) to investigate polymeric blends of industrial interest composed by isotopically labeled styrene-butadiene rubber (SBR) and polystyrene (PS) oligomers of size smaller than the Kuhn length. The EFWS are sensitive to the onset of liquid-like motions across the calorimetric glass transition, allowing the selective determination of the "microscopic" effective glass transitions of the components. These are compared with the "macroscopic" counterparts disentangled by the analysis of the DSC results in terms of a model based on the effects of thermally driven concentration fluctuations and self-concentration. At the microscopic level, the mixtures are dynamically heterogeneous for blends with intermediate concentrations or rich in PS, while the sample with highest content of the fast SBR component looks as dynamically homogeneous. Moreover, the combination of SANS and DSC has allowed determining the relevant length scale for the α-relaxation through its loss of equilibrium to be ≈30 Å. This is compared with the different characteristic length scales that can be identified in these complex mixtures from structural, thermodynamical, and dynamical points of view because of the combined approach followed. We also discuss the sources of the non-Gaussian effects observed for the atomic displacements and the applicability of a Lindemann-like criterion in these materials.

Infrared Spectral Classification of Natural Bitumens for Their Rheological and Thermophysical Characterization

Natural bitumens consist of many molecules whose chemical composition depends on the oilfield and determines the physicochemical properties of the bitumens as materials. Infrared (IR) spectroscopy is the fastest and least expensive method to assess the chemical structure of organic molecules, which makes it attractive in terms of rapid prediction of the properties of natural bitumens based on their composition evaluated in this way. In this work, IR spectra were measured for ten samples of natural bitumens significantly different in properties and origin. Based on the ratios of certain IR absorption bands, bitumens are proposed to be divided into paraffinic, aromatic, and resinous. In addition, the internal relationship between IR spectral characteristics of bitumens, such as polarity, paraffinicity, branchiness, and aromaticity, is shown. A study of phase transitions in bitumens by differential scanning calorimetry was carried out, and the use of a heat flow differential to find hidden points of bitumens' glass transitions is proposed. Furthermore, the dependences of the total melting enthalpy of crystallizable paraffinic compounds on the aromaticity and branchiness of bitumens are demonstrated. A detailed study of bitumens' rheology in a wide temperature range was carried out, and characteristic features of rheological behavior for different bitumen classes are revealed. Based on the viscous properties of bitumens, their glass transition points were found and compared with the calorimetric glass transition temperatures and nominal solid-liquid transition points obtained from temperature dependences of bitumens' storage and loss moduli. The dependences of viscosity, flow activation energy, and glass transition temperature of bitumens on their IR spectral characteristics are shown, which can be used to predict the rheological properties of bitumens.

Mechanical vs calorimetric glass transition temperature in the oxidation of linoleic acid from condensed κ-carrageenan/glucose syrup systems

Lipid oxidation remains a concern leading to deterioration of the organoleptic quality in processed goods, but it should be minimized by considering changes in the structural properties of foods. The present work investigates the effect of glass transition temperature on the oxidation of linoleic acid at different concentrations of κ-carrageenan/glucose syrup. A combination of 0.5, 1, 2 and 3% (w/w) κ-carrageenan and 82.5, 82, 81, 80% (w/w) glucose syrup were mixed with 1.5% (w/w) linoleic acid and 0.5% (w/w) lecithin to prepare samples with a total solid content of 85% (w/w). Physicochemical properties of these mixtures were recorded using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). This was followed by estimation of the mechanical (Tgm) and calorimetric (Tgc) glass transition temperatures using small deformation dynamic oscillation in-shear and modulated differential scanning calorimetry (MDSC). The linoleic acid oxidation in the condensed polysaccharide/co-solute system was evaluated by monitoring the accumulation of hydroperoxide (ROOH) with UV–vis spectroscopy over a wide temperature range (−25 to 0 °C). The oxidation phase was modelled following a sigmoidal kinetic model indicating initiation and propagation stages of lipid oxidation. ROOH production increased as a function of time and temperature. The structural relaxation of the polymeric matrix influenced the oxidation rate at the initiation stage. At the propagation phase, Tgm appears to control the rate of ROOH formation (kf) and decomposition (kd) in all preparations, as compared to Tgc, an outcome that makes the former an important concept of quality control.

Thermodynamic heat-transfer phenomena in nanostructured glassy substances: a comparative study on g-As5Se95 and g-As55Se45

Nanostructurization-driven responses in calorimetric heat-transfer phenomena are compared for glassy arsenoselenides at different levels of their molecular network organization, namely in high-polymerized g-As5Se95 and low-polymerized g-As55Se45, employing multifrequency temperature-modulated DSC-TOPEM® method complemented with Raman scattering microspectroscopy. It is shown that high-polymerized network composed of AsSe3 pyramids interlinked by Se chains with small number of Se8 molecular units decoupled from this network prevails in melt-quenched and nanomilling-derived g-As5Se95. Transition to more polymerized network due to incorporation of destroyed Se8 molecules into glass backbone occurs in this glass under nanostructurization. As a result, nanostructurization-driven calorimetric response in g-As5Se95 dominates by size-induced glass-transition temperature depression. The low-polymerized structure of g-As55Se45 is built of As–Se network enriched with tetra-arsenic selenide molecular units decoupled from this network. Molecular-to-network transition owing to nanomilling-driven destruction of these cage molecules and their incorporation into newly polymerized glass-forming backbone occurs in g-As55Se45 resulting in strong increase in calorimetric glass-transition temperature.

Elucidation of segmental relaxations of silica‐filled cis‐polybutadiene rubber composites

AbstractThere has been a lot of interest in characterizing polymer chain dynamics of rubber compounds because it is thought to underpin the exceptional mechanical properties of composites. We studied the effect of precipitated silica on segmental mobility of cis‐polybutadiene rubber by using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). It was found that the calorimetric glass and melting transitions of silica‐filled master batch materials were essentially identical to those of the gum rubber, showing no dependence of silica loading and silane treatment. And, we observed in calorimetric measurement a change in the melting transition step for the vulcanizates. The results were correlated to the change of chemical crosslinks caused by various factors filler agglomeration and adsorption effect that tended to decrease chemical crosslink density and silane modification increased it. The DMA results demonstrated that the second peak in loss modulus versus temperature curve for the quenched vulcanizates was assigned to melting peak, and this peak disappeared at a slow cooling rate, which coincided well with DSC results. Moreover, crystalline parts constrained amorphous regions such that the glass transition temperature was raised for the cooled vulcanizates with high chemical crosslinks.

Accelerated aging of 18 years rejuvenated polylactide bottles by fast scanning calorimetry

AbstractThis study focuses on the accelerated physical aging kinetics of rejuvenated polylactide (PLA) that has previously been processed and stored during 18 years under ambient conditions. The finish of a conditioned PLA bottle is subjected to structural relaxation for times varying between 0.001 and 1000.0 min at 45°C, that is, 15°C below its calorimetric glass transition temperature. The recovery of in‐situ aged PLA is monitored by fast scanning calorimetry and it is observed that the thermodynamic equilibrium is reached within the experimental aging time. Moreover, the time evolution of the enthalpy of recovery finds consistency with results obtained for PLA granules which did not undergo additional processing neither prolonged storage nor service life conditions. Thus, it is deduced that both processing and storage do not induce major degradation reactions that could affect the aging kinetics. Therefore, the behavior of a structurally rejuvenated amorphous PLA is depicted through the one of an unaged PLA.

Disentangling the Calorimetric Glass-Transition Trace in Polymer/Oligomer Mixtures from the Modeling of Dielectric Relaxation and the Input of Small-Angle Neutron Scattering.

We have disentangled the contributions to the glass transition as observed by differential scanning calorimetry (DSC) on simplified systems of industrial interest consisting of blends of styrene–butadiene rubber (SBR) and polystyrene (PS) oligomer. To do this, we have started from a model previously proposed to describe the effects of blending on the equilibrium dynamics of the α-relaxation as monitored by broadband dielectric spectroscopy (BDS). This model is based on the combination of self-concentration and thermally driven concentration fluctuations (TCFs). Considering the direct insight of small-angle neutron scattering on TCFs, blending effects on the α-relaxation can be fully accounted for by using only three free parameters: the self-concentration of the components φselfSBR and φselfPS) and the relevant length scale of segmental relaxation, 2Rc. Their values were determined from the analysis of the BDS results on these samples, being that obtained for 2Rc ≈ 25Å in the range usually reported for this magnitude in glass-forming systems. Using a similar approach, the distinct contributions to the DSC experiments were evaluated by imposing the dynamical information deduced from BDS and connecting the component segmental dynamics in the blend above the glass-transition temperature Tg (at equilibrium) and the way the equilibrium is lost when cooling toward the glassy state. This connection was made through the α-relaxation characteristic time of each component at Tg, τg. The agreement of such constructed curves with the experimental DSC results is excellent just assuming that τg is not affected by blending.

Pressure-annealed high-density amorphous ice made from vitrified water droplets: A systematic calorimetry study on water's second glass transition.

In previous work, water's second glass transition was investigated based on an amorphous sample made from crystalline ice [Amann-Winkel et al., Proc. Natl. Acad. Sci. U. S. A. 110, 17720 (2013)]. In the present work, we investigate water's second glass transition based on the genuine glassy state of high-density water as prepared from micron-sized liquid water droplets, avoiding crystallinity at all stages. All the calorimetric features of water's second glass transition observed in the previous work are also observed here on the genuine glassy samples. This suggests that the glass transition indeed thermodynamically links amorphous ices continuously with deeply supercooled water. We proceed to extend the earlier study by investigating the effect of preparation history on the calorimetric glass transition temperature. The best samples prepared here feature both a lower glass transition temperature Tg,2 and a higher polyamorphic transition temperature Tons, thereby extending the range of thermal stability in which the deeply supercooled liquid can be observed by about 4K. Just before the polyamorphic transition, we observe a spike-like increase of heat capacity that we interpret in terms of nucleation of low-density water. Without this spike, the width of water's second glass transition is 15K, and the Δcp amounts to 3 ± 1JK-1 mol-1, making the case for the high-density liquid being a strong liquid. We suggest that samples annealed at 1.9GPa to 175K and decompressed at 140K to ≥0.10GPa are free from such nuclei and represent the most ideal high-density amorphous glasses.

Structural, shear and volume relaxation in a commercial float glass during aging

Density, Raman spectroscopy and viscosity measurements are utilized to probe, respectively, the volume, structural and shear relaxation behavior of a Na-Ca-Mg silicate glass of standard commercial float composition at ∼80 °C below its calorimetric glass transition. The results, when taken together, indicate that the lowering of fictive temperature of the glass during aging results in a Q-species disproportionation of the type Q2+Q4→2Q3, and all three relaxation processes are characterized by stretched exponential kinetics with similar average timescale (〈τ〉∼ 300 h) and stretching exponent (β ∼ 0.4), implying a close mechanistic relationship. It is hypothesized that the coexistence of strongly and weakly constrained domains or structural moieties in the network of a glass or supercooled liquid can give rise to a temporal decoupling between the structural and shear relaxation processes, as has been reported in some of the recent studies in the literature.

Interplay of vitrification and ice formation in a cryoprotectant aqueous solution at low temperature

The proneness of water to crystallize is a major obstacle to understanding its putative exotic behavior in the supercooled state. It also represents a strong practical limitation to cryopreservation of biological systems. Adding some concentration of glycerol, which has a cryoprotective effect preventing, to some degree, water crystallization, has been proposed as a possible way out, provided the concentration is small enough for water to retain some of its bulk character and/or for limiting the damage caused by glycerol on living organisms. Contrary to previous expectations, we show that, in the “marginal” glycerol molar concentration ≈ 18%, at which vitrification is possible with no crystallization on rapid cooling, water crystallizes upon isothermal annealing even below the calorimetric glass transition of the solution. Through a time-resolved polarized neutron scattering investigation, we extract key parameters, size and shape of the ice crystallites, fraction of water that crystallizes, and crystallization time, which are important for cryoprotection, as a function of the annealing temperature. We also characterize the nature of the out-of-equilibrium liquid phases that are present at low temperature, providing more arguments against the presence of an isocompositional liquid–liquid transition. Finally, we propose a rule of thumb to estimate the lower temperature limit below which water crystallization does not occur in aqueous solutions.