Thermoreversible Gels Research Articles

Network Formation and Mechanical Properties of Telechelic Associating Polymers with Fixed Junction Multiplicity

A statistical–mechanical theory of thermoreversible gelation which is formed by monodisperse telechelic associating polymers with junction multiplicity of three is developed. In the present theory, the effect of loop formation is considered. Using the theory, the properties of the system are obtained, such as the state of association of polymers, the sol–gel transition line, and the number concentration of elastically effective chains. In addition, a Monte Carlo simulation of a bead‐spring model of monodisperse telechelic associating polymers is performed. The simulation results are in good agreement with the present theoretical results. Furthermore, the shear modulus is calculated by an application of phantom network theory and compared with the experimental data. The theoretical results agree well with the experimental results. It is shown that the loop formation occurs especially in dilute regime and causes the decrease of the modulus in the regime. image

Heat-induced aging of agar solutions: Impact on the structural and mechanical properties of agar gels

Thermoreversible gels are commonly prepared by cooling down to ambient temperature, aqueous polymer solutions first brought to a boil for a short time. Here, we study the effect of the latter duration on the subsequent gelation of an agar solution. Increasing the incubation time at high temperature (T = 80 °C) from hours to a few days leads to the hydrolysis and the oxidation of the polysaccharides, and results in the decrease of the viscosity and the pH of the solution. Samples withdrew at different incubation times are cooled down to form gels whose structure and mechanical properties are systematically determined. Cryoelectron microscopy and X-ray diffraction experiments reveal that agar gels formed from solutions of increasing incubation times, display a coarser microstructure composed of micron-sized foils which result from the condensation of the polysaccharides, and contrast with the fibrous-like microstructure of gels prepared from a fresh agar solution. Along with structural changes, a prolonged incubation time of the agar solution at T = 80 °C leads to weaker gels than those made from fresher solutions, and extensive macro-indentation experiments coupled to direct visualization show that the gel rupture scenario turns from brittle to ductile-like as the incubation time increases. Our study suggests that the incubation time of agar solutions at high temperature could be used as an external control parameter to tune the mechanical properties of agar-based gels.

Nanoporous-crystalline poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) aerogels

Abstract Monolithic aerogels of poly(2,6-dimethyl-1,4-phenylene)oxide (an industrially relevant polymer generally known as polyphenyleneoxide or PPO), have been prepared and characterized. These aerogels obtained by supercritical carbon dioxide extraction of thermoreversible gels of high molecular weight PPO present an apparent porosity typically in the range 70%–95% and high surface area values up to 750 m 2 /g. Moreover these aerogels are characterized by an excellent sorption uptake of organic pollutants at low vapor pressure and good recyclability by thermal regeneration. Good mechanical properties and dimensional stability of PPO monoliths is due to the polymer high molecular weight which ensures formation of a fibrillar morphology, already in the precursor gel. Sorption capacity and recyclability of PPO aerogels are mostly due to their crystalline phase: (i) its nanoporous-crystalline structure assures high specific surface areas; (ii) its high melting temperature assures a high thermal monolith stability as well as easy and cheap recovery of absorbed guest molecules by thermal treatments rather than by solvent extractions.

Mechanically Tunable, Readily Processable Ion Gels by Self-Assembly of Block Copolymers in Ionic Liquids.

Room temperature ionic liquids are of great interest for many advanced applications, due to the combination of attractive physical properties with essentially unlimited tunability of chemical structure. High chemical and thermal stability, favorable ionic conductivity, and complete nonvolatility are just some of the most important physical characteristics that make ionic liquids promising candidates for emerging technologies. Examples include separation membranes, actuators, polymer gel electrolytes, supercapacitors, ion batteries, fuel cell membranes, sensors, printable plastic electronics, and flexible displays. However, in these and other applications, it is essential to solidify the ionic liquid, while retaining the liquid state properties of interest. A broadly applicable solidification strategy relies on gelation by addition of suitable triblock copolymers with the ABA architecture, producing ion gels or ionogels. In this paradigm, the A end blocks are immiscible with the ionic liquid, and consequently self-assemble into micellar cores, while some fraction of the well-solvated B midblocks bridge between micelles, forming a percolating network. The chemical structures of the A and B repeat units, the molar mass of the blocks, and the concentration of the copolymer in the ionic liquid are all independently tunable to attain desired property combinations. In particular, the modulus of the resulting ion gel can be readily varied between 100 Pa and 1 MPa, with little sacrifice of the transport properties of the ionic liquid, such as ionic conductivity or gas diffusivity. Suitable A blocks can impart thermoreversible gelation (with solidification either on heating or cooling) or even photoreversible gelation. By virtue of the nonvolatility of ionic liquids, a wide range of processing strategies can be employed directly to prepare ion gels in thin or thick film forms, including solvent casting, spin coating, aerosol jet printing, photopatterning, and transfer printing. For higher modulus ion gels it is even possible to employ a manual "cut and stick" strategy for easy device fabrication. Ion gels prepared from common triblock copolymers, for example, with A = polystyrene and B = poly(ethylene oxide) or poly(methyl methacrylate), in imidazolium based ionic liquids provide exceptional performance in membranes for separating CO2 from N2 or CH4. The same materials also are the best available gate dielectrics for printed plastic electronics, because their high capacitance endows organic transistors with milliamp output currents for sub-1 V applied bias, with switching speeds that can go well beyond 100 kHz, while being amenable to large area roll-to-roll printing. Incorporation of well-designed electroluminescent (e.g., Ru(bpy)3-based) or electrochromic (e.g., viologen-based) moieties into ion gels held between transparent electrodes yields flexible color displays operating with sub-1 V dc inputs.

A Review on organogel for skin aging

Skin aging is one of the prominent problems associated with skin as each part of body ages with the time, skin is the external organ where the sign and symptoms of aging are readily evident. However cosmetics as well as pharmaceutical approaches delayed skin aging. Gel are best fitted in all these essential criteria because of their excellent appearance, smoothness, desired consistency, fast drug release, ease of manufacturing and quality assessment and admirable stability. Recently gel formulation have been modified to yield an advance drug delivery system known as ―organogels‖. Gel define as a semi-solid preparation having an external solvent phase, apolar [organogel] or polar [hydrogel] immobilized within the space available of a three dimensional network structure. Lecithin is a natural surfactant isolated from eggs or soya bean, when it combined with water and non-polar solvent, it form gels. PLO gels have gained importance in recent years as transdermal drug delivery system. It is a thermodynamically stable, visco-elastic system, which is non-irritating, odorless and biodegradable. Pluronic F127 or poloxamer is a copolymer of polyoxyethylene and polyoxypropylene which forms a thermoreversible gel in concentrations between 15-30%w/v. Water plays the role of a structure-forming agent and stabilizes the process of gel formation as it solubilizes the pluronic and other hydrophilic drugs. PLO gel system facilitates the delivery of hydrophilic as well as lipophilic drugs owing to the presence of both oil and aqueous phases within the gel system.

Cationic Main‐Chain Polyelectrolytes with Pyridinium‐Based p‐Phenylenevinylene Units and Their Aggregation‐Induced Gelation

Cationic polyelectrolytes find potential applications in electronic device fabrication, biosensing as well as in biological fields. Herein, a series of cationic main‐chain polyelectrolytes with pyridinium‐based p‐phenylenevinylene units that are connected via alkylene spacers of varying lengths are synthesized by a base‐catalyzed aldol‐type coupling reaction. Their mean average molecular weights range from 15 000 to 32 000 g mol‐1, corresponding to about 16–33 repeat units. Due to the presence of alkyl side‐chains and alkylene spacers as well as cationic hard‐charges the polymers are endowed with amphiphilic character and hence, aggregation of these polyelectrolytes at high concentration leads to thermoreversible physical gel formation in dimethyl sulfoxide accompanied by interchain interactions. Morphological analysis shows spherical aggregates in case of C16‐Poly‐S12 in dimethyl sulfoxide. Dependence of gelation behavior on the length of alkyl side‐chains and alkylene spacers of the polyelectrolytes are addressed. image

Temperature-Responsive Nanofibrillar Hydrogels for Cell Encapsulation.

Natural extracellular matrices often have a filamentous nature, however, only a limited number of artificial extracellular matrices have been designed from nanofibrillar building blocks. Here we report the preparation of temperature-responsive nanofibrillar hydrogels from rod-shaped cellulose nanocrystals (CNCs) functionalized with a copolymer of N-isopropylacrylamide and N,N'-dimethylaminoethyl methacrylate. The composition of the copolymer was tuned to achieve gelation of the suspension of copolymer-functionalized CNCs at 37 °C in cell culture medium and gel dissociation upon cooling it to room temperature. The mechanical properties and the structure of the hydrogel were controlled by changing copolymer composition and the CNC-to-copolymer mass ratio. The thermoreversible gels were used for the encapsulation and culture of fibroblasts and T cells and showed low cytotoxicity. Following cell culture, the cells were released from the gel by reducing the temperature, thus, enabling further cell characterization. These results pave the way for the generation of injectable temperature-responsive nanofibrillar hydrogels. The release of cells following their culture in the hydrogels would enable enhanced cell characterization and potential transfer in a different cell culture medium.

Optimization of thermoreversible poloxamer gel system using QbD principle

The objective of this study was to optimize thermoreversible gel formulations with respect to their gelation temperature and solubilizing capacity, using quality by design (QbD) principles based on design of experiment (DoE). Independent variables, X1, X2 and X3, represent the weight percentages of poloxamer 407 (P407), poloxamer 188 (P188) and the polyethylene glycol 400, respectively (these polymers are either thermoreversible gelling agents or solubilizers). Emodin, a poorly water-soluble compound, was used as a model drug. Fifteen gel formulations were prepared based on the compositions generated by an extreme vertices type of mixture design using a DoE software, in which their gelation temperatures (Y1) and emodin solubility (Y2) were measured. The gelation temperature and emodin solubility were each described adequately using a full cubic model and a quadratic model, respectively. Theoretical and experimental responses showed linearity with R2=0.9943 for the gelation temperature and R2=0.9629 for emodin solubility. The design space was established from the models describing the gelation temperature (test accuracy: 104.5%) and emodin solubility (test accuracy: 96.6%). This study demonstrates successful application of DoE for prediction of gelation temperature and solubility of emodin thermoreversible poloxamer gel (PG). In conclusion, the present DoE approach has led to the establishment of a design space and manufacturing control strategy for gel formulations.

Thermoreversible mucoadhesive in situ nasal gel for treatment of Parkinson’s disease

Parkinson’s disease is a degenerative disorder of the central nervous system (CNS). The most obvious symptoms are movement-related such as shaking, rigidity, slowness of movement and difficulty with walking, rigid muscular movements and difficulty in chewing and swallowing especially solid dosage forms. Ropinirole is an anti-Parkinson drug that has low oral bioavailability which is primarily due to first-pass metabolism. The objective of proposed work was to increase bioavailability of ropinirole and avoid patient discomfort by formulating thermoreversible in situ nasal gel. Thermoreversible nasal gels were prepared by cold method using Pluronic F-127 and hydroxy methyl propyl cellulose (HPMC K4M) as gelling agents. Formulations were evaluated for various parameters such as drug content, pH, gelling time, gelling temperature, gel strength, mucoadhesive force, ex vivo diffusion, histological studies and in vivo bioavailability. Formulations displayed gelation at nasal temperature and the gelation time was found to be less than mucociliary clearance time. The nasal residence time was seen to be increased due to mucoadhesion and increased gel strength. The nasal gel formulations showed ex vivo drug release between 56–100% in 5 h. Histological study of sheep nasal mucosa revealed that the gel had a protective effect on the mucosa unlike plain ropinirole which showed evidence of moderate cellular damage. A fivefold increase in bioavailability in brain was observed on nasal administration as compared to IV route. Thermoreversible in situ nasal gel was found to a promising drug delivery for Parkinsonian patients.

Bioinspired tuning of glycol chitosan for 3D cell culture

Three-dimensional (3D) cell culture systems have promising applications compared with conventional two-dimensional cell culture systems. Herein, we report a facile method for the formation of 3D spheroids using novel thermo-reversible polysaccharide-based hydrogels. A series of thermo-reversible hydrogels consisting of N-acyl glycol chitosans (NAGCs) are synthesized through a simple N-acylation reaction, and the degree of acylation is finely tuned to obtain adequate thermo-reversible properties and gel stability. Among the NAGCs, N-hexanoyl glycol chitosan is the most thermo-sensitive and is highly effective for forming multi-cellular spheroids when used to coat the surfaces of cell culture dishes. Cell spheroids are effectively formed at various cell concentrations, and their spheroid shape and cellular functions are well maintained for longer times. The hydrogel culture system is also useful for co-cultures that mimic a biological microenvironment. Our thermo-reversible hydrogels may offer a convenient method for the development of in vitro 3D cell culture systems to provide enhanced performance in tissue regeneration, organ-on-chips, drug screening research and other biomedical applications. Modifying the crustacean-derived molecule chitosan produces thermosensitive hydrogels for realistic, spherical cell growth studies. Three-dimensional (3D) cell environments are better platforms for exploring cell structure and function than traditional Petri dishes, but typically require complex ‘hanging drop’ substrates or micromoulds. Researchers from the Korea Institute of Toxicology and Chungnam National University have developed a simpler 3D cell culture using a water-filled polysaccharide that can transform into a gel on demand thanks to the thermo-responsive property. In experiments, cells such as cardiomyocytes spontaneously aggregated to form spheroids after only 24 hours immersion in the chitosan-based hydrogel. Harvesting was performed using temperature-reduction techniques suitable for large-scale processes. Cytotoxicity tests revealed that these cultures were safe and could be used to co-culture different cells to realize better biomimicking. We developed glycol chitosan-based thermo-reversible hydrogels that can provide a facile, convenient and reproducible method for the formation of 3D cell spheroids. The spontaneous formation of spheroids on HGC-coated plates was completed within 1 day. Furthermore, this system can be useful for co-culturing heterotypic cells to form spheroids that mimic biological systems.

Thermoreversible Gels Composed of Colloidal Silica Rods with Short-Range Attractions

Dynamic arrest transitions of colloidal suspensions containing nonspherical particles are of interest for the design and processing of various particle technologies. To better understand the effects of particle shape anisotropy and attraction strength on gel and glass formation, we present a colloidal model system of octadecyl-coated silica rods, termed as adhesive hard rods (AHR), which enables control of rod aspect ratio and temperature-dependent interactions. The aspect ratios of silica rods were controlled by varying the initial TEOS concentration following the work of Kuijk et al. (J. Am. Chem. Soc., 2011, 133, 2346-2349) and temperature-dependent attractions were introduced by coating the calcined silica rods with an octadecyl-brush and suspending in tetradecane. The rod length and aspect ratio were found to increase with TEOS concentration as expected, while other properties such as the rod diameter, coating coverage, density, and surface roughness were nearly independent of the aspect ratio. Ultrasmall angle X-ray scattering measurements revealed temperature-dependent attractions between octadecyl-coated silica rods in tetradecane, as characterized by a low-q upturn in the scattered intensity upon thermal quenching. Lastly, the rheology of a concentrated AHR suspension in tetradecane demonstrated thermoreversible gelation behavior, displaying a nearly 5 orders of magnitude change in the dynamic moduli as the temperature was cycled between 15 and 40 °C. The adhesive hard rod model system serves as a tunable platform to explore the combined influence of particle shape anisotropy and attraction strength on the dynamic arrest transitions in colloidal suspensions with thermoreversible, short-range attractions.

Development and Characterization of Thermosensitive intranasal Gel Containing Paliperidone Loaded Microspheres

Purpose: The objective of the present investigation was to fabricate a thermosensitive gel containing paliperidone loaded microspheres for the treatment of schizophrenia for brain delivery through nasal route. Incorporation of drug in to microspheres and then in to gel should increase the duration of release and nasal duration time respectively. Material and Method: Ethyl cellulose microspheres containing paliperidone palmitate were prepared by emulsification of ethyl acetate dispersion containing polymer and drug with aqueous external phase containing polysorbate 80. Amount of ethyl cellulose and polysorbate 80 were identified as critical formulation variables influencing the drug release at critical time points, percentage yield and particle size. These factors were studied using 2 factors and 3 level face centered factorial design using Design Expert ® . Drug-excipient compatibility was ascertained using FTIR analysis. The paliperidone microspheres were then incorporated in to Pluronic F127 and HPMC gel having required thermo sensitive and muco adhesive properties. Gel containing microspheres was subjected to Ex vivo permeation study, irritation study using sheep nasal mucosa and pharmacodynamic study (spontaneous motor activity in mice). Results: Microspheres that could sustain the drug release up to 8 hours were developed. Thermoreversible gel having required thermo sensitive and muco adhesive properties was developed. The Ex vivo permeation study and pharm a codynamic study of the drug loaded microsphere containing gel confirmed the release up to 8 hours. The histopathology study showed absence of irritation on sheep nasal mucosa. Conclusion: Paliperidone palmitate loaded microspheres containing gel could prolong and target the drug release to brain and therefore give prolonged and intense action. Key words: Nose to brain delivery, Paliperidone palmitate, Pharmacodynamic activity, Thermoreversible gel, Desirability index.

Theoretical Study of Network Formation and Mechanical Properties of Physical Gels with a Well-Defined Junction Structure.

A statistical-mechanical theory of thermoreversible gelation considering loops for the system consisting of bifunctional polymer units carrying A functional groups and trifunctional units carrying B functional groups at their ends is constructed. We obtain the sol-gel transition line and the properties of the post-gel region as functions of the polymer concentration, temperature, association constant, and loop parameter using the present theory. In this article, we calculate the number concentration of elastically effective chains in the gel region and obtain the shear modulus by an application of the phantom network theory. The shear modulus obtained by this theory is lower than that obtained by conventional theory because of loop formation. We find that these theoretical results are in good agreement with the experimental data.

Scaling law, fractal analysis and rheological characteristics of physical gels cross-linked with sodium trimetaphosphate

The scaling behavior and fractal analysis of basil seed gum (BSG) cross-linked with sodium trimetaphosphate (STMP) have been investigated by rheological small amplitude oscillatory shear measurements. Storage modulus and critical strain (γo) of the gels exhibited power law relationships with BSG concentration. Based on the power-law exponent values, the fractal dimension (df) of gels was estimated using scaling models, revealed the weak-link regime of BSG. The df values lied well within the range of fractal dimension values (1.5–2.8) reported for protein gels. However, they slightly differed from df for diffusion-limited and reaction limited cluster-cluster aggregation processes. Stress sweep test was shown that STMP addition to BSG made a stronger gel than that of BSG lacking STMP. Mechanical spectrum of gels was also revealed that adding STMP can improve the elasticity of gels. BSG had a tan δ of >0.1, indicating paste-like weak gel, while tan δ of BSG-STMP has approached to 0.1 exhibited the character of a cross-linked network near to “true gel”. BSG-STMP was also recognized as a thermo-reversible physical gel, which gelation and thermal properties did not affect by STMP. Therefore, the scaling behavior can be applied for hydrocolloids gels to extract structural information through rheological measurements. Moreover, the rheological characteristics of BSG-STMP showed it can be used as a proper hydrogel in food and pharmaceutical applications.

Thermoreversible gelation and scaling behavior of Ca2+-induced κ-carrageenan hydrogels

The effect of calcium cations (Ca2+) on thermoreversible gelation properties, microstructure, and scaling behavior of κ-carrageenan in aqueous solution was studied by micro-differential scanning calorimetry (micro-DSC), field emission scanning electron microscopy (FESEM) and rheology. It was found that κ-carrageenan molecules self-associated into fibrils, and the diameter and number of fibrils increased with increasing Ca2+ ion concentration. The formation and melting of κ-carrageenan hydrogel was thermally reversible and extremely sensitive to Ca2+ ions. The viscoelastic property at the gel point was examined using the Winter-Chambon criterion to obtain the critical relaxation exponent n and the critical gel strength Sg. n and Sg were found to decrease and increase with increasing Ca2+ ion concentration respectively. The normalized gel strength, Sg/Ca2+, was not independent of Ca2+ ion concentration, suggesting a strong effect of Ca2+ ions on both size and density of junctions formed during gelation. A schematic diagram has been proposed to explain how Ca2+ ions could facilitate the coil-helix transition, leading to the formation of more aggregates acting as junctions.

Physical Gelation of α-Helical Copolypeptides.

Owing to its rod-like α-helical secondary structure, the synthetic polypeptide poly(γ-benzyl-l-glutamate) (PBlG) can form physical and thermoreversible gels in helicogenic solvents such as toluene. The versatility of PBlG can be increased by introducing functionalizable comonomers, such as allylglycine (AG). In this work we examined the secondary structure of PBlG and a series of statistical poly(γ-benzyl-l-glutamate-co-allylglycine) copolypeptides, varying in composition and chain length, by circular dichroism (CD), Fourier-transform infrared (FTIR) and Raman spectroscopy, and wide-angle X-ray scattering (WAXS). The secondary structure of PBlG and the copolypeptides presented dissimilarities that increased with increasing AG molar fraction, especially when racemic AG units were incorporated. The physical gelation behavior of these copolypeptides was analyzed by temperature-sweep (1)H NMR and rheological measurements. The study revealed that both copolypeptide composition and chain length affected secondary structure, gelation temperature, and gel stiffness.

Fluorescent poly(n-hexyl isocyanate) triblock terpolymer and its thermoreversible gels

Thermoreversible gels were obtained from the well-defined triblock terpolymer poly(n-hexyl isocyanate)-b-polybutadiene-b-poly(n-hexyl isocyanate) (PHIC-b-PB-b-PHIC). PHIC-b-PB-b-PHIC adopted a helical conformation and exhibited florescence in solution. The gels were prepared in both n-heptane and n-octane. The gelation concentration and temperature could be affected by various factors. Hydrogen bonding and intermolecular aggregation were the driving forces to form stable thermoreversible gels. Atomic force microscopy (AFM) showed that the microstructure of the gels consisted of aggregates of fibrous nanoribbons. Because of their thermosensitivity and fluorescence, the thermoreversible gels have potential applications in sensors and temperature-sensitive switches.

Effect of mechanical properties on the release of meloxicam from poloxamer gel bases.

Thermoreversible gel of meloxicam, efficient for the treatment of joint diseases, was aimed to prepare for night application available for chronotherapy in this study. Poloxamer 407 and 188 polymers were used at 20-30% w/w as a vehicle in combination with different additives (polyvinylmethylether maleic anhydride copolymer, hydroxypropyl methylcellulose, polyethylene glycol 400, dimethyl sulfoxide, sodium chloride). Characterisation of prepared gels was evaluated by viscosity and texture analysis, and the effect of formulation variables on the gel formulations were evaluated by in vitro drug release and erosion studies. Between the investigated gel bases, Poloxamer 407-hydroxypropyl methylcellulose gel was found to be ideal due to its gel strength (1.560±0.0135 N), viscosity (312.3±2.06 cP) and release characteristics. These promising results could be encouraging for further studies to make it an alternative to commercial dosage forms.

The impact of damage accumulation on the kinetics of network strength recovery for a physical polymer gel subjected to shear deformation

ABSTRACTShear rheophysical experiments were used to quantify the kinetics of strength recovery of model thermoreversible polymer gels that were fractured and ultimately sheared to different total magnitudes of strain (700 and 4000%) before resting for set periods of time. Relationships between the amount of strength recovered and the normalized ratio of resting times to characteristic relaxation times were developed. It was found that gels displayed fully healed networks within timescales that were 2–3 orders of magnitude greater than the gel's characteristic relaxation time. Gels deformed to 700% applied strain either healed slower at lower gel concentrations as compared to experiments at larger applied strains due to possible viscous heating, or healed faster from incomplete fracture propagation for higher gel concentrations. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1693–1701

Mechano‐Responsive, Thermo‐Reversible, Luminescent Organogels Derived from a Long‐Chained, Naturally Occurring Fatty Acid

The gelating ability of an α-diketo derivative of oleic acid, 9,10-dioxooctadecanoic acid (DODA), is investigated. DODA can gelate aromatic liquids and many other organic liquids. By contrast, none of the liquids examined can be gelated by the methyl ester of DODA. DODA is a more efficient gelator than stearic acid and the monoketo derivative due to its more extensive intermolecular dipole-dipole interactions. Formation of organogels of DODA can be induced by both thermal and mechanical stimuli, during which the luminescent and mechanical properties can be modulated significantly. The emission from DODA in 1-octanol exhibits a large, reversible, hypsochromic shift (≈25 nm) between its thermally cycled gel and sol states. The emission changes have been exploited to probe the kinetics of the aggregation and deaggregation processes. DODA is the simplest gelator of which we are aware that exhibits a reversible shift in the emission. Although the self-assembled fibrillar networks of the DODA gels in 1-octanol, benzonitrile, or silicone oil are crystalline, isothermal mechanical cycling between the gel and the sol states is rapid and can be repeated several times (i.e., they are thixotropic). The single-crystal structure of DODA indicates that extended intermolecular dipole-dipole interactions are crucial to the thermal and mechanical formation of DODA gels and the consequential changes in emissive and mechanical properties. From analyses of structural information, gelator packing, and morphology differences, we hypothesize that the mechanical destruction and reformation of the gel networks involves interconversion between the 3D networks and 1D fiber bundles. The thermal processes allow the fibrillar 3D networks and their 0D components (i.e., isolated molecules or small aggregates of DODA) to be interconverted. These results describe a facile approach to the design of mechano-responsive, thermo-reversible gels with control over their emission wavelengths.