Thermoreversible Gels Research Articles

Fabrication of Ionic Supramolecular Oleogel Lubricants Enhanced with Liquid Metal Nanodroplets for Superior Tribological Performance.

Supramolecular Oleogel lubricants provide a versatile and reliable strategy for optimizing the long-term dispersion stability of nanoadditives in the base oils. In this work, GLM-based ionic gelators constructing supramolecular oleogels were prepared by adding ultrasonically treated gallium-based liquid metal (GLM) nanodroplets carrying free radicals and vinyl-containing ionic liquids (ILs) directly to a free radical polymerization system of polymer gelators. The electrostatic interactions between the ionic liquids and GLM nanodroplets enhanced the cross-linking degree of supramolecular gels and formed denser self-assembled structures. The as-prepared GLM-based ionic oleogels as thermoreversible gels exhibit exceptional thixotropic properties. Compared to the base oil PAO10, the coefficient of friction (COF) for both GLM@IGel-1 and GLM@IGel-2 decreased significantly from 0.192 to 0.097, while the wear volume dropped from 100.10 × 104 μm3 to 13.28 × 104 μm3 for GLM@IGel-1, and to 9.69 × 104 μm3 for GLM@IGel-2. In addition, GLM@IGel-2 demonstrates a higher load-bearing capacity of 550 N due to further chemical cross-linking by ionic liquids. The outstanding lubrication performance of GLM-based ionic oleogels is achieved by the synergy of GLM nanodroplets and gel lubricants, promoting the formation of a stable tribo-chemical reaction film.

Light-Emitting Coordination Polymers: Stimuli-Responsive Gels, PMMA-Based Composite Films, and UV-Shielding.

Lanthanide-based light-emitting coordination polymers (CPs) and CP gels (CPGs) have significance for applications in optical systems, image processing/multiplexing, and optical sensors. In this study, we report two new luminescent CPs (EuL-CP (1) and TbL-CP (2)) and CPGs (EuL-gel (5) and TbL-gel (6)) using lanthanide(III) ions (Ln(III) = Eu(III) and Tb(III)) and 4-(4-carboxyphenyl)-2,2:6,2-terpyridine ligand (L) capable of forming stable thermoreversible gels. Probable structures of EuL-CP (1) and TbL-CP (2) and the formations of EuL-gel (5) and TbL-gel (6) are proposed based on adequate computational studies. The CPGs are stimuli-responsive and could be utilized as invisible security inks for encryption. Further, poly(methyl methacrylate) (PMMA) polymer doped with respective CPs (0.75 wt %) is found to be suitable for forming composite films with UV-shielding properties.

Fabrication and characterization of novel curcumin-loaded thermoreversible high amylose maize starch emulsion gel

This study developed a novel thermoreversible emulsion gel system based on high amylose maize starch (HAMS) and investigated the impact of the oil-to-water ratio on its physicochemical properties and encapsulation performance (using curcumin as model guest molecule). Electron microscopy showed a tightly porous network structure of the HAMS-based emulsion gels. Thermal results revealed a sol-gel transition occurring in the range of 59.41 to 67.64 °C for the prepared emulsion gels. Rheological analysis suggested that all samples displayed shear-thinning behavior and HAMS-based emulsion gels exhibited typical gel-like behavior with the gel strength bolstered by higher aqueous phases. Particle size analysis showed that droplet size of emulsion gel decreased from 245 to 184 nm with increased starch aqueous phase content. Texture profile analysis indicated enhanced strength, hardness, and chewiness of the emulsion gel with increased aqueous phases. Curcumin encapsulation efficiency in the HAMS-based emulsion gel also improved with higher aqueous phase content, reaching up to 93.82 %, which attributed to the smaller droplets caused increased interfacial area. The novel HAMS-based emulsion gel system showed considerable encapsulation capacity and desirable mechanical properties. It provided valuable insights into the application of starch-based emulsion gels in food and medical area.

Development, characterization and pharmacokinetic evaluation of selegiline HCl loaded cubosomal thermoreversible mucoadhesive gel for nose to brain delivery

Selegiline HCl (SGH) is MAO-B inhibitor with limited bioavailability due to extensive hepatic metabolism. Thus, this work aims to formulate and evaluate SGH loaded intranasal thermoreversible cubosomal gel in order to enhance its bioavailability and ensure efficient brain targeting. Experimental design and Artificial Neural Network (ANN) were explored to optimize the formulation. Gellan gum and konjac gum were used as gelling agent and mucoadhesive agent respectively to formulate mucoadhesive in situ nasal gel. Optimized formulation of SGH loaded cubosomal dispersion exhibits average particle size (166.8 ± 3.12 nm), entrapment efficiency (72.85 ± 1.50 %), and drug release at 6 h (89.15 ± 1.04 %). In vitro drug release analysis demonstrated the sustained release pattern. In vivo pharmacokinetic studies in Swiss Albino mice showed approximately 1.90-fold increase in Cmax and AUC(0-t) in brain after intranasal administration. The Cmax and AUC for drug solution was found to be 4.3828 ± 0.02 ng/mL, 19.4166 ± 0.06 ng min/mL and for cubosomal gel it was 11.7665 ± 0.32 ng/mL, 36.9216 ± 0.41 ng min/mL respectively. Furthermore, the stability study was executed for estimation of shelf life of optimized formulation. The shelf life of SGH loaded cubosmal gel was found to be 20.64 months which demonstrate its long-term stability. The in vitro and in vivo evaluation endorsed that the fabricated cubosomal in situ nasal gel could be the promising approach for nose to brain delivery of SGH in Parkinson's therapy.

Structure, characterization, and application of a novel thermoreversible emulsion gel fabricated by citrate agar

A novel thermoreversible emulsion gel was successfully prepared with citrate agar (CA) as the sole emulsifier. Compared with native agar gel emulsion, CA gel emulsion (CAGE) formed a stable emulsion gel when the CA concentration was increased to 1.25 % (w/w). Results of time-temperature scanning experiments showed that the emulsion gel rapidly transformed into liquid emulsion when heated to 40–50 °C and then solidified into emulsion gel after cooling to the critical temperature of solidification. The emulsion gel had stable sol–gel transformation ability after seven cycles repeated heating–cooling treatment (HCT) at 85 °C and 4 °C. However, the stability of emulsion gels gradually decreased because of the large-droplet formation during heating, which affected the CA molecular-reconfiguration network structure in cooling. The conjunction analysis of microstructure and properties of the emulsion gel indicated that its stability depended primarily on the spatial repulsion and electrostatic repulsion provided by CA gel, and the main factor driving thermal reversibility was the temperature-responsive gelation performance of CA. The retention of quercetin was >90.23 % after seven HCTs because CAGEG enhanced the homogeneity and stability of the droplets.

In-Vitro, Ex-Vivo & In-Vivo Assessment of Brain Targeted Thermoreversible Mucoadhesive In-Situ Intranasal Gel of Carmustine for the Treatment of Glioblastoma

In-Vitro, Ex-Vivo & In-Vivo Assessment of Brain Targeted Thermoreversible Mucoadhesive In-Situ Intranasal Gel of Carmustine for the Treatment of Glioblastoma

Influence of the thermal shrinkage-induced volume contraction on the yielding behavior of waxy oil

The present article investigates the effect of thermal shrinkage on the yielding behavior of waxy oil gel. The paper compares constant gap and constant normal force measurement protocols to examine the effect of measurement protocol on the rheological behavior of thermoreversible gel. The findings of this study reveal that the extent of stress overshoot and yield stress in a constant shear-rate start-up flow shows a lower magnitude in a constant gap protocol compared to a constant normal force protocol. The decrease in gel strength in the former protocol is mainly attributed to the formation of voids. These voids cause localized fractures within the crystal network. In contrast, in the constant normal force measurement protocol, gel contraction is compensated by utilizing a variable gap setting. Variable gaps compensate for the lower specific volume of the gel after crystallization, minimizing void formation and subsequent rupture of the crystal network. Hence, the gel network formed using the constant normal force protocol is more homogeneous, eliminating the uncertainties in yield stress measurement. Finally, the effect of thermal history, wax content, and aging period on the yield stress values highlights notable findings. Contrary to the conventionally accepted results, the aging period is found to impact the yield stress negatively, and a nonmonotonic relationship between the cooling rate and yield stress is noticed under the constant gap protocol. Thus, the results obtained under the constant normal force protocol are more reliable and can help in developing a fundamental understanding of the yielding behavior.

Layer-over-Layer Electrostatic Self-Assembly of Bioresourced Compounds in Thermoreversible Polylactide Gels as an Effective Approach to Enhance the Flame Retardancy of Aerogels.

Polylactide is a high potential polymer that can satisfy the growing demand for sustainable and lightweight materials in construction, packaging, and structural applications. However, their high flammability poses a serious concern. Herein, with the aid of solvent exchange and noncovalent interactions, poly(l-lactide) (PLLA) thermoreversible gel was modified with sodium alginate (SA), chitosan (CS), and phytic acid (PA) via a layer-over-layer approach. Freeze-drying of the modified hydrogel furnished a highly flame retardant aerogel with shape stability and no shrinkage. The modified PLLA aerogel (PLLA@SA@CS@PA) exhibited self-extinguishment of flame, the highest limiting oxygen index of any porous polylactide (∼32%), and a tremendous reduction in flammability parameters such as the heat release rate, heat release capacity, total heat release, etc. A comprehensive mechanism of flame retardancy was proposed. This work provides a sustainable strategy for the flame retardant modification of semicrystalline polymer-based aerogels and is expected to expand their practical applications in various industrial sectors.

Brain Targeted Drug Delivery System of Carmustine: Design, Development, Characterization, in vitro, ex vivo Evaluation and in vivo Pharmacokinetic Study

The treatment of gliomas remains difficult task. Carmustine is a drug that is used in the treatment of gliomas. Flexible liposomes embedded in situ thermoreversible nasal gel preparations of Carmustine were studied for in vitro carmustine release, ex vivo carmustine permeation and carmustine release kinetics. The epithelial layers of nasal tissue were found to be intact and undamaged during histological analysis. Intranasal administration of optimized flexible liposomes embedded in a nasal gel showed higher Cmax (Approximately two-fold), AUC0→t (Approximately three-fold), AUC0→∞ (Approximately six-fold), and lower Tmax (1 h) in the brain, compared to intravenous injection of carmustine. The present study demonstrates that the flexible liposome embedded thermoreversible in situ intranasal gel of carmustine improved the targeted uptake of carmustine in the brain through the nasal delivery system and could be a reliable and effective delivery system for carmustine in the treatment of gliomas.

Reversibility in the Physical Properties of Agarose Gels following an Exchange in Solvent and Non-Solvent.

Agarose forms a homogeneous thermoreversible gel in an aqueous solvent above a critical polymer concentration. Contrary to the prevailing consensus, recent confirmations indicate that agarose gels are also stable in non-solvents like acetone and ethanol. A previous study compared gel characterisations and behaviours in water and ethanol, discussing the gelation mechanism. In the current work, the ethanol gel is exchanged with water to explore the potential reversibility of the displacement of water in agarose. Initially, the structure is characterised using 1H NMR in DMSO-d6 and D2O solvents. Subsequently, a very low yield (0.04) of methyl substitution per agarobiose unit is determined. The different gels after stabilisation are characterised using rheology, and their physical properties are compared based on the solvent used. The bound water molecules, acting as plasticizers in aqueous medium, are likely removed during the exchange process with ethanol, resulting in a stronger and more fragile gel. Next, the gel obtained after the second exchange from ethanol back to water is compared with the initial gel prepared in water. This is the first time where such gel has been characterised without undergoing a phase transition when switching from a good solvent to a non-solvent, and vice versa, thereby testing the reversibility of the solvent exchange. Reversibility of this behaviour is demonstrated through swelling and rheology experiments. This study extends the application of agarose in chromatography and electrophoresis.

Development and characterization of plant derived wastes Nano-formulation loaded in thermo-reversible gel for burn healing: An effort towards Sustainable Development

The duty of research is to suggest solutions to ailments affecting humans. Recently, there has been a demand that these solutions should be environmentally responsible, eco-friendly and coincide with sustainable development goals. From this perspective, the objective of this study was to develop thermo-reversible and healing promoting gel formulations. The gel base incorporated Natural Plant derived Wastes’ ethanolic extracts of either Kiwi peels (KE) or Yucca seeds (YE) (antioxidant, vitamins and anti-inflammatory natural agent) loaded chitosan nanoparticles for enhancement of burn healing performance. Comparative evaluation was done to all formulations to find the best competitor to conventional marketed drug formulations. Both extracts were standardized using HPLC. The lipoid content of YE was investigated using GC-MS, showing a content of 32.78 and 15.7 %of linoleic and pamiticmethyl esters, respectively. The nanoparticles characterization and the in-vitro physicochemical characteristics of the final dosage form formulations were assessed, revealing86.65 and 76.6 % entrapment efficiency, 311.4 and 198.1 nm particle size for KE and YE nanoformulations, respectively. The efficacy of the formulations was investigated in vivo against the commercial burn healing drug Mebo®, biochemical parameters and histopathology were statistically investigated. Reduction in wound area reached 69.12 and 72.01 % on day 12 for KE and YE nanoformulations, respectively. The YE encapsulated within chitosan nanoparticles loaded gel showed a promising and a significant healing effect comparable to the most commonly used marketed drug product (Mebo®) and possible mechanisms involved in the phases of healing were illustrated. Eco-friendly waste herbal extracts-loaded chitosan nanoparticles in thermo-reversible gel have been successfully developed from the two extracts: Kiwi peels and yucca seeds for burn and wound healing. This confirms the possible use of traditional medicines in advanced formulations to satisfy the future market of pharmaceuticals.

Development and Characterization of Thermoreversible In-situ Gel Containing Curcumin Nanoparticles for Nasal Delivery: Design, Ex-Vivo Study

The present study aimed to develop and evaluate thermoreversible in situ nasal gel containing Curcumin nanoparticles. Curcumin nanoparticles were prepared by the ionic gelation method. These formulations were evaluated for entrapment efficiency, particle size, zeta potential, and In vitro drug release. Particle size and zeta potential of F1 formulation were found to be 299 nm, 0.1 mV, and entrapment efficiency was found to be87.2%. From the formulations, F1 shows maximum amount of drug released in a sustained manner for a prolonged period time. Hence F1formulation was selected as optimized and further used for thermoreversible in situ nasal gel by using 2×2 factorial designs. The thermoreversible nasal gel was evaluated for the gelation temperature (33˚C), viscosity (10550cps) and spreadability (17.29±0.3 gm*cm/sec). Further, the prepared gel (F1G3) was evaluated for ex vivo permeation study for12 hours and it shows maximum amount of drug release in a controlled manner. The % CDR of thermoreversible in situ gel formulation F1G3 was found to be 86.27% which follow the Higuchi model. The 'n' value of the formulation was found to be more than 0.5. This indicate that the release approximates the non-fickain diffusion mechanism.
 Keywords: Curcumin nanoparticles, Carbopol 934, PF127, Thermoreversible in situ gel, Cold method, Nasal delivery.

Enhancing Mucoadhesive Properties of Gelatin through Chemical Modification with Unsaturated Anhydrides.

Gelatin is a water-soluble natural polyampholyte with poor mucoadhesive properties. It has traditionally been used as a major ingredient in many pharmaceuticals, including soft and hard capsules, suppositories, tissue engineering, and regenerative medicine. The mucoadhesive properties of gelatin can be improved by modifying it through conjugation with specific adhesive unsaturated groups. In this study, gelatin was modified by reacting with crotonic, itaconic, and methacrylic anhydrides in varying molar ratios to yield crotonoylated-, itaconoylated-, and methacryloylated gelatins (abbreviated as Gel-CA, Gel-IA, and Gel-MA, respectively). The successful synthesis was confirmed using 1H NMR, FTIR spectroscopies, and colorimetric TNBSA assay. The effect of chemical modification on the isoelectric point was studied through viscosity and electrophoretic mobility measurements. The evolution of the storage (G') and loss (G'') moduli was employed to determine thermoreversible gelation points of modified and unmodified gelatins. The safety of modified gelatin derivatives was assessed with an in vivo slug mucosal irritation test (SMIT) and an in vitro MTT assay utilizing human pulmonary fibroblasts cell line. Two different model dosage forms, such as physical gels and spray-dried microparticles, were prepared and their mucoadhesive properties were evaluated using a flow-through technique with fluorescent detection and a tensile test with ex vivo porcine vaginal tissues and sheep nasal mucosa. Gelatins modified with unsaturated groups exhibited superior mucoadhesive properties compared to native gelatin. The enhanced ability of gelatin modified with these unsaturated functional groups is due to the formation of covalent bonds with cysteine-rich subdomains present in the mucin via thiol-ene click Michael-type addition reactions occurring under physiologically relevant conditions.

EVALUATION OF IN VITRO CYTOTOXIC POTENTIAL OF DIFFERENT CARMUSTINE FORMULATIONS AGAINST U-87 MG HUMAN GLIOBLASTOMA CELL LINE

Glioblastoma (GBM) is a frequent as well as violent type of brain tumor. In this research work, different carmustine formulations were prepared and screened for their cytotoxic activity against U-87 MG glioblastoma and normal human fibroblast L-929 cell lines. The flexible liposomes embedded in situ nasal gel exhibited maximum percentage of growth inhibition against U-87 MG glioblastoma cell line, and in situ nasal gel exhibited lowest percentage of growth inhibition against U-87 MG glioblastoma cell lines. Flexible liposomes embedded in situ nasal gel is observed to be safe and biocompatible against normal human fibroblast L-929 cell line. In cellular uptake study, U-87 MG cell line treated with flexible liposomes embedded in situ thermoreversible intranasal gel emitted stronger and higher intensity fluorescence. It seems that the presence of flexible liposomes embedded in situ thermoreversible nasal gel inside the tumor cells, and would be the best carmustine delivery approach for the management of GBM.

Poly(vinylidene fluoride) Aerogels with α, β, and γ Crystalline Forms: Correlating Physicochemical Properties with Polymorphic Structures.

Strategic customization of crystalline forms of poly(vinylidene fluoride) (PVDF) aerogels is of great importance for a variety of applications, from energy harvesters to thermal and acoustic insulation. Here, we report sustainable strategies to prepare crystalline pure α, β, and γ forms of PVDF aerogels from their respective gels using a solvent exchange strategy with green solvents, followed by a freeze-drying technique. The crucial aspect of this process was the meticulous choice of appropriate solvents to enable the formation of thermoreversible gels of PVDF by crystallization-induced gelation. Depending on the polymer-solvent interactions, the chain conformation of PVDF can be modulated to obtain gels and aerogels with specific crystalline structures. The crystalline pure α-form and piezoelectric β-form aerogels were readily obtained by using cyclohexanone and γ-butyrolactone as gelation solvents. On the other hand, the γ-form aerogel was obtained using a binary solvent system consisting of dimethylacetamide and water. These aerogels with distinct crystalline structures exhibit different morphologies, mechanical properties, hydrophobicities, acoustic properties, and electrical properties. Measurement of thermal conductivity for these aerogels showed exceptionally low thermal conductivity values of ∼0.040 ± 0.003 W m-1 K-1 irrespective of their crystal structures. Our results showcase the fabrication approaches that enable PVDF aerogels with varied physicochemical properties for multifunctional applications.

Designing thermoreversible gels for extended release of mosquito repellent.

Mosquito-borne diseases are responsible for 700 000 deaths annually. Current outdoor protective strategies primarily focus on direct skin application of commercial repellents (i.e., aerosol sprays or topical lotions) which are typically limited to efficacy times of ≤10 hours due to rapid evaporation and dermal absorption. Consequently, frequent reapplication for continuous protection can increase associated health hazards and cause noncompliance. This study utilizes Hansen solubility parameter modeling to design physical gels composed of insect-repelling N,N-diethyl-meta-toluamide (DEET) and modacrylic copolymer poly(acrylonitrile-co-vinyl chloride) (P(AN-VC)). The P(AN-VC)/DEET composites exhibit tunable and reversible sol-gel transition temperatures that can meet the thermomechanical stability demands of the intended application and permit facile transition to commercial melt processing techniques such as injection molding, filament spinning, or film casting. P(AN-VC)/DEET gel films demonstrate mosquito repellency for more than half a year-performing longer than any other known material to date-due to the high reservoir of repellent and its desorption hindrance from the polymer matrix. Therefore, P(AN-VC)/DEET gels hold significant potential for extended protection against mosquitos and other biting arthropods.

UV-Crosslinked Poly(N-isopropylacrylamide) Interpenetrated into Chitosan Structure with Enhancement of Mechanical Properties Implemented as Anti-Fouling Materials.

High-performance properties of interpenetration polymer network (IPN) hydrogels, based on physically crosslinked chitosan (CS) and chemically crosslinked poly(N-isopropylacrylamide) (PNiPAM), were successfully developed. The IPN of CS/PNiPAM is proposed to overcome the limited mechanical properties of the single CS network. In this study, the viscoelastic behaviors of prepared materials in both solution and gel states were extensively examined, considering the UV exposure time and crosslinker concentration as key factors. The effect of these factors on gel formation, hydrogel structures, thermal stabilities of networks, and HeLa cell adhesion were studied sequentially. The sol-gel transition was effectively demonstrated through the scaling law, which agrees well with Winter and Chambon's theory. By subjecting the CS hydrogel to the process operation in an ethanol solution, its properties can be significantly enhanced with increased crosslinker concentration, including the shear modulus, crosslinking degree, gel strength, and thermal stability in its swollen state. The IPN samples exhibit a smooth and dense surface with irregular pores, allowing for much water absorption. The HeLa cells were adhered to and killed using the CS surface cationic charges and then released through hydrolysis by utilizing the hydrophilic/hydrophobic switchable property or thermo-reversible gelation of the PNiPAM network. The results demonstrated that IPN is a highly attractive candidate for anti-fouling materials.

Synthesis of Poly(propylene oxide)-Poly(N,N'-dimethylacrylamide) Diblock Copolymer Nanoparticles via Reverse Sequence Polymerization-Induced Self-Assembly in Aqueous Solution.

Sterically-stabilized diblock copolymer nanoparticles comprising poly(propylene oxide) (PPO) cores are prepared via reverse sequence polymerization-induced self-assembly (PISA) in aqueous solution. N,N'-Dimethylacrylamide (DMAC) acts as a cosolvent for the weakly hydrophobic trithiocarbonate-capped PPO precursor. Reversible addition-fragmentation chain transfer (RAFT) polymerization of DMAC is initially conducted at 80% w/w solids with deoxygenated water. At 30-60% DMAC conversion, the reaction mixture is diluted to 5-25% w/w solids. The PPO chains become less solvated as the DMAC monomer is consumed, which drives in situ self-assembly to form aqueous dispersions of PPO-core nanoparticles of 120-190 nm diameter at 20 °C. Such RAFT polymerizations are well-controlled (Mw/Mn ≤ 1.31), and more than 99% DMAC conversion is achieved. The resulting nanoparticles exhibit thermoresponsive character: dynamic light scattering and transmission electron microscopy studies indicate the formation of more compact spherical nanoparticles of approximately 33 nm diameter on heating to 70 °C. Furthermore, 15-25% w/w aqueous dispersions of such nanoparticles formed micellar gels that undergo thermoreversible (de)gelation on cooling to 5 °C.

Effectiveness of a Developed In-House Breast Phantom in Enhancing the Knowledge of Mammographic Positioning in Radiologic Technology Students: A Quasi-Experimental Study in Thailand

Objective: This study aimed to develop an in-house breast phantom, and assess students’ knowledge and satisfaction after using it for mammographic positioning training.Material and Methods: The breast phantom was designed in a half-body shape, and constructed primarily using gelcoat resin, polyurethane foam, and thermoreversible gel. Additionally, silicone type RA-210, known for its high flexibility, tensile strength, elongation at break (620%), and ability to revert to its original shape, was incorporated. This study evaluated the effectiveness of the breast phantom utility in improving students’ knowledge through a nine-item questionnaire; employing a one-group pre-post design. The participants, consisting of 63 Radiologic Technology students, whom rated their satisfaction with the phantom for training purposes using a five-point Likert scale.Results: The mean knowledge score for the breast phantom positioning significantly improved from 5.35±1.61 points (pretest) to 7.32±1.20 points (post-test), following training (p-value<0.001). The students expressed high overall satisfaction with this training aid (4.49±0.58 points).Conclusion: Our breast phantom demonstrates its potential as an effective educational tool that enhances Radiologic Technology students’ understanding of mammographic positioning. However, further research is warranted to develop more advanced phantoms and to explore alternative experimental designs for effective teaching methods.

Thermoreversible Gel-Dispersed Liquid Crystals.

A simple model is introduced to describe phase behaviours of binary mixtures of a thermoreversible gel and a low-molecular-weight liquid crystal (LC). We predict novel phase diagrams on the temperature-concentration plane, including sol-gel transition, nematic-isotropic phase transition, and phase separation. At high temperatures, the phase separation between the isotropic sol and gel phases appears. As the temperature decreases, we have the phase separation between nematic sol and isotropic gel phases, in which the nematic domains are dispersed in the isotropic gel phase. We suggest that thermoreversible gelation of reactive molecules mixed with LCs will become one of the new classes of polymer-dispersed liquid crystals.