Gelation Mechanism Research Articles

Rheo-optic in situ synchronous study on the gelation behaviour and mechanism of waxy crude oil emulsions

An improved rheo-optic in situ synchronous measurement system was employed to investigate the gelation behaviour and mechanism of waxy crude oil emulsions. By combining transmitted natural light and reflected polarized light microscopy, a multiangle composite light source was built to achieve the simultaneous observation of wax crystals and emulsified water droplets, as well as their dynamic aggregation process. Main outcomes on the microscopic mechanism were obtained by developed microscopic image processing method. It was found that the microstructure of W/O waxy crude oil emulsion has the evolution of “individual structure--homogeneous aggregate structure--heterogeneous coaggregate structure--floc structure” during the static cooling, which results in the four stages during gelation process. Different from previous studies, the aggregation of emulsified water droplets was found to be more significant and contributes to the formation and development of the wax crystals-emulsified water droplets coaggregate, which plays a decisive role in the further evolution of the gelled microstructure. Time series microscopic images show the dynamic aggregation of emulsified water droplets and wax crystals. Two different aggregation behaviours between wax crystals and water droplets were observed. That wax crystals can not only embed in gaps between adjacent water droplets and enhance the structure, but also surround the outside of the water droplets and continue to grow resulting in the interconnection of different coaggregates to form a larger floc structure. In addition, correlation between viscoelasticity and microstructure evolution of waxy crude oil emulsions of different water contents was discussed. With increasing water contents, the microstructure is changed from wax crystal flocculation structure as the main skeleton and the emulsified water droplets embedded in it, into the aggregation of emulsified water droplets occupying the main position. When the number of wax crystals and water droplets reaches a certain ratio, did wax crystals form coaggregates with emulsified water droplets, and the remaining wax crystals formed an overall flocculation structure, the viscoelasticity of the waxy crude oil emulsion is the highest. • Dynamic aggregation of wax crystals and emulsified water droplets was observed. • Two different aggregation behaviours between wax crystals and water droplets were found. • Aggregation of water droplets was found to be significant for the microstructure evolution. • New microscopic mechanism for gelation of W/O Waxy Crude Oil Emulsion was presented. • Correlation between viscoelastic and microstructure evolution was discussed. • Different ratios between wax crystals and water droplets lead to different viscoelasticity.

Change of network structure in agarose solution during gelation studied by multiple particle tracking and NMR measurements

The gelation mechanism of agarose solution on cooling has been successfully elucidated by measurements from macroscopic to microscopic scales using a dynamic rheometer, the multiple particle tracking with two different diameters and the pulsed-field-gradient stimulated echo (PGSTE) 1H NMR. The dynamic rheometer detected the gradual increase of G’ in the temperature range from 55 to 40 °C before the steep increase at the gelation temperature. The time-averaged mean square displacement (msd) obtained by multiple particle tracking for particles with diameter of 270 nm and 1000 nm revealed the generation of micro domains with the network structure obstructing particle diffusion. Further, the NMR measurements gave detailed information about the change of molecular mobility for agarose chains during the formation of the micro domains and the macroscopic overall network structure. These results suggest a gelation mechanism and gel network structure including the formation of micro domains in the temperature range from 55 to 40 °C and the connection among the micro domains by agarose aggregates to form the overall network structure at the gelation temperature.

The role of amide groups in the mechanism of acid-induced pectin gelation: A potential pH-sensitive hydrogel based on hydrogen bond interactions

Gelation of amidated pectin in the acid environment with the absence of calcium has been found, but the mechanism and gel properties are still not fully understood, especially the role of amide groups. In this study, a series of pectins with different degrees of amidation (DA) were prepared by ammonia reaction, and their structural characteristics including neutral sugar contents, molecular weight contribution, and molecular morphology were fully identified. Acid-induced hydrogels with various DA were then obtained to investigate the impact of amino groups on pectin gelation. Results showed that the higher the DA, the faster the gelation process, and the more stable the gel network. Dynamic rheological and pH stability tests confirmed the essential roles of low pH value (<3.5) and high DA (>49.76%) on the amidated pectin gelation without calcium. Hydrogen bonds were identified as the main interaction for the amidated gel mechanism and enabled the thermo-reversible properties of amidated gels. High content of amide groups allowed the formation of a denser gel network structure with greater mechanical strength, stronger thermo-reversibility, and higher pH stability.

Comparative Large Amplitude Oscillatory Shear (LAOS) Study of Ionically and Physically Crosslinked Hydrogels

Hydrogels are highly versatile and widely applicable materials within various scientific, technological, and food sectors. Alginate and gelatin hydrogels, along with their crafted variations, are possibly the most common ones. However, the ionic crosslinking of alginate-Ca++ is a different gelation mechanism than the physical crosslinking of gelatin. In this work, we prepare alginate-Ca++ hydrogels using individual layer gelation and experimentally evaluate LAOS rheological behavior. We apply shear-stress decomposition using the MITlaos software and obtain the elastic and viscous contributions within the nonlinear response of the individual alginate-Ca++ layer. We compare these results with the nonlinear responses of the gelatin-alginate ex situ individual layer. The strain-sweep patterns are similar, with loss modulus overshoot. The applied shear can destroy the larger-scale structural units (agglomerate/aggregates), resulting in analogous patterns. However, the critical strain points are different. Based on the shear-thickening ratio T of the LAOS analysis, it can be assumed that the common feature of ex situ preparation, i.e., gelation as individual layers, provides a matching bulk microstructure, as the hydrogels differ significantly at a molecular-binding level.

Dually crosslinked injectable alginate-based graft copolymer thermoresponsive hydrogels as 3D printing bioinks for cell spheroid growth and release

In this work a dual crosslinked network based on sodium alginate graft copolymer, bearing poly(N-isopropylacrylamide-co-N-tert-butylacrylamide) P(NIPAM-co-NtBAM) side chains was developed and examined as a shear thinning soft gelating bioink. The copolymer was found to undergo a two-step gelation mechanism; in the first step a three-dimensional (3D) network is formed through ionic interactions between the negatively ionized carboxylic groups of the alginate backbone and the positive charges of Ca2+ divalent cations, according to the “egg-box” mechanism. The second gelation step occurs upon heating which triggers the hydrophobic association of the thermoresponsive P(NIPAM-co-NtBAM) side chains, increasing the network crosslinking density in a highly cooperative manner. Interestingly, the dual crosslinking mechanism resulted in a five-to-eight-fold improvement of the storage modulus implying reinforced hydrophobic crosslinking above the critical thermo-gelation temperature which is further boosted by the ionic crosslinking of the alginate backbone. The proposed bioink could form arbitrary geometries under mild 3D printing conditions. Last, it is demonstrated that the proposed developed bioink can be further utilized as bioprinting ink and showcased its ability to promote human periosteum derived cells (hPDCs) growth in 3D and their capacity to form 3D spheroids. In conclusion, the bioink, owing its ability to reverse thermally the crosslinking of its polymer network, can be further utilized for the facile recovery of the cell spheroids, implying its promising potential use as cell spheroid-forming template bionk for applications in 3D biofabrication.

Experimental and mechanism investigation on flowability and wax deposition of waxy crude oil with dissolved CH4 by pressurized laboratory apparatus

In offshore oilfields, crude oils often contain dissolved gas, and are unavoidably transported under pressure. However, the flowability and wax deposition of crude oils with dissolved gas are rarely investigated. In this paper, Methane (CH4) was used as a similar substitute for the dissolved gas in crude oils, and a series of pressurized laboratory apparatuses were developed to study the influencing mechanism of dissolved CH4 on the flowability and wax deposition of Changqing waxy crude oil. It was found that with the increase of the dissolved CH4 pressure, the crude oil flowability was improved, and the wax deposition rate was inhibited. However, the wax appearance temperature (WAT), the average wax content of wax deposits, and the mass of wax diffused into wax deposits all increased accordingly. This was mainly attributed to the influence of dissolved CH4, which can effectively increase the intermolecular distance between wax molecules, decrease the intermolecular forces, and weaken the strength of wax crystals to overlap each other. The improvement of rheological properties, on the one hand, promotes the diffusion of wax molecules, which leads to the increase in the mass of wax diffused into wax deposits; on the other hand, it increases the wax content required for the formation of wax deposits according to the dynamic gelation mechanism, thus resulting in the decrease of wax deposition rate. Also, the wax stripping effect during the deposition and depressurization processes cannot be ignored. The research results have guiding significance for the optimal design of the gathering and transportation pipeline network and the calculation of wax deposition.

Statistical analysis of gelation mechanism of high-temperature CO2-responsive smart gel system

The CO2 capture, utilization and storage (CCUS) are very important. CO2-responsive materials have good CO2 responsiveness and can play a certain role in CCUS. However, the use temperature of CO2-responsive surfactant is relatively low, and the main factors affecting their performance are still not clear, seriously affecting their large-scale application. In this work, a kind of high-temperature CO2-responsive surfactant was synthesized, and it can form a high-temperature CO2-responsive smart gel system when combined with counter ion salt. The effects of temperature, surfactant concentration, salinity, aging time and oil content on the properties of the CO2-responsive smart gel system were studied by means of rheological experiments and SEM characterization. Combined with statistical analysis methods, a large number of experimental data were analyzed and fitted, a mathematical model was constructed. The mathematical model was highly feasible and statistically significant. Based on the mathematical model, the main factors affecting the performance of the CO2-responsive smart gel system were analyzed, and the gelation mechanism of the gel system was obtained. This work is expected to provide some guidance for the future application of the CO2-responsive smart gel.

Gelation mechanism of high soluble dietary fiber okara-egg tofu induced by combined treatment of steam explosion and enzymatic hydrolysis

Okara contains a large amount of insoluble dietary fiber (IDF), but it is usually treated as waste. This study was to develop a high soluble dietary fiber (SDF) egg tofu. The SDF content in okara was increased by steam explosion and enzymatic hydrolysis. The gelation mechanism of high SDF egg tofu was evaluated by adding modified okara (MO), non-modified okara (NMO) and available fraction of modified okara (AMO) into the egg tofu. The results showed that the content of SDF in okara was increased from 2.14% to 32.13% after modification. The content of SDF in high SDF egg tofu (MO Gel) was about 2.6 times that of ordinary egg tofu (Control Gel). The texture and rheological properties showed that the addition of MO and NMO improved hardness and viscoelasticity of egg tofu, while the addition of AMO destroyed the gel network structure. The addition of MO and NMO enhanced the WHC of egg tofu, while the addition of AMO promoted the immobilized water to free water, and the microstructure characterization laterally confirmed it. The above results proved that the insoluble dietary fiber (IDF) in MO and NMO played a positive role in egg tofu gel. Only addition of SDF (AMO Gel) destroyed the network structure of egg tofu gel, while the presence of appropriate content of IDF was conducive to enhance the stability of gel structure. This work provided theoretical understanding for the preparation of high SDF egg tofu.

Preparation and resource utilization of sludge-based fire-preventive and extinguishing composite gel for coal mine

We prepared a sludge-based fire-preventive and extinguishing composite gel for coal mines using sludge, HPAM, water glass, and sodium bicarbonate as the main raw materials. Orthogonal test was used to analyze the effects of each component and its level on the performance of gel to determine the optimal ratio of gel and then tested its fire-preventive and extinguishing characteristics. Finally, the gelling mechanisms of the gel are discussed. The composite gel prepared at the optimal level showed that the gelling time can be maintained at about 55 s, the water retention can reach up to 58.6% in 12 h at 100 °C. The gel has a dense microstructure and uniform pores, and has the best inhibition rate of coal spontaneous combustion. As compared with other materials, the coal piled with gel did not reignite. TGA showed that the gel hinders oxidation and complete combustion of coal. The in-situ infrared analysis confirmed that the coal sample treated with gel has a low content of aliphatic hydrocarbon and hydroxyl group. Infrared spectroscopy analysis indicated that the sludge in the gel plays the role of filler. The organic-inorganic composite network structure formed by the sludge and the gel not only prevents the system from water loss and coal oxidation but also absorbs a large amount of sludge and realizes the resource utilization of sludge. Therefore, the preparation of composite gel reduces the secondary pollution of sludge and lowers the cost of the material, making it an economical and environmentally friendly fire-preventive and extinguishing material.

Controlling the gelation time of sodium silicate gelants for fluid management in hydrocarbon reservoirs

An efficient gel-based treatment of fractures and high-permeability layers requires the precise placement of the gelant within the formation, which is highly dependent on the gelation time. This study proposes an optimal method that reduces the uncertainties associated with the exact placement of sodium silicate gelants in a formation. This method is based on the control of the gelation time, so that these potent and eco-friendly blocking agents can be used more effectively in water shut-off, profile modification, and carbon storage projects. We proposed a new pre-flush operation and gelation protocol for sodium silicate gelants; gelation time experiments were conducted using a rheometer and through characterization of gel strength codes. To improve the pre-flush operation, the masking potential of citric acid is examined in this study. We show that citric acid is capable of complexing formation water ions, thus small amounts of citric acid can delay the gelation time by up to 8 h. In previous studies, silica nanoparticles were used as nucleation promoters in sodium silicate gelants, which required large amounts of surfactant for their stabilization. As an alternative, we propose a new gelation mechanism that is based on the adsorption tendency and nucleation ability of silica nanoparticles. We show that, based on their adsorption tendency, silica nanoparticles initially form an H+ layer around themselves and do not participate in the gelation reaction. At the same time, they can reduce the reaction rate of silicates, which postpones the gelation time by up to 14% (at 0.15 wt% of silica nanoparticles in defined concentrations of sodium silicate and acid). However, we observed that adding silica nanoparticles at a concentration less than 0.15 wt% or greater than 0.3 wt% accelerates gelation. But when the H+ layer breaks down, the nanoparticles intensify the gelation process through nucleation. The mechanistic insights are derived from an experimental study in which the concentrations of silica nanoparticles, sodium silicate, and gelling agent are varied. Also, experiments in a wide range of temperatures and concentrations of silica nanoparticles, sodium silicate, and citric acid showed that shielding silica nanoparticles with H+ ions released from the gelling agent keeps the nanoparticles stable in the gelant without the use of other additives. Accordingly, this mechanism, in addition to having the ability to decrease the gelation rate, increases the nucleation capacity, and reduces the complexity and cost of the system. The results of this work provide guidelines for preparing sodium silicate gelants and optimizing their gelation process.

Sequential Sol-Gel Self-Assembly and Nonclassical Gel-Crystal Transformation of the Metal-Organic Framework Gel.

Metal-organic framework (MOF) gel, an emerging subtype of MOF structure, is unique in formation and function; however, its evolutionary process remains elusive. Here, the evolution of a model gel-based MOF, UiO-66(Zr) gel, is explored by demonstrating its sequential sol-gel self-assembly and nonclassical gel-crystal transformation. The control of the sol-gel process enables the observation and characterization of structures in each assembly stage (phase-separation, polycondensation, and hindered-crystallization) and facilitates the preparation of hierarchical materials with giant mesopores. The gelation mechanism is tentatively attributed to the formation of zirconium oligomers. By further utilizing the pre-synthesized gel, the nonclassical gel-crystal transformation is achieved by the modulation in an unconventional manner, which sheds light on crystal intermediates and distinct crystallization motions ("growth and splitting" and "aggregation and fusion"). The overall sol-gel and gel-crystal evolutions of UiO-66(Zr) enrich self-assembly and crystallization domains, inspire the design of functional structures, and demand more in-depth research on the intermediates in the future.

Preparation of high internal phase Pickering emulsion gels stabilized by glycyrrhizic acid-zein composite nanoparticles: Gelation mechanism and 3D printing performance

High internal phase Pickering emulsion (HIPPEs) for three-dimensional (3D) printing have attracted increasing attention for application to foods. In this study, glycyrrhizic acid-zein composite nanoparticles (ZGNPs) were prepared via hydrogen bonding and electrostatic interactions. The properties of the ZGNPs were characterized by particle size, ζ-potential, and electron microscopy analysis. Using ZGNPs as emulsifiers, HIPPEs with an oil phase volume fraction of 75% were successfully fabricated. These HIPPEs showed good storage stability, shear-thinning behavior, and high viscoelasticity. Furthermore, their rheology and stability characteristics meant they could be used to as edible bio-inks for 3D printing applications. These HIPPEs was able to 3D-print selected shapes with high resolution and shape fidelity. Our results open new possibilities for producing Pickering emulsion gels with improved performance, which could be used as 3D printing inks for future food manufacturing and nutrition delivery systems.

Epidemic Models for Chemical Gel Phase Transformation: Effect of Optical Measurements with Different Wavelengths

In our previous work we characterized the sol-gel transition of chemical and physical gels in terms of epidemic models which describe the spread of a disease in a society. We have shown that gelation in chemical gels can be represented by the Susceptible-Infected-Recovered (SIR) model, while the gelation mechanism of physical gels can be represented by the Susceptible-Infected-Susceptible (SIS) model. These studies were based on optical measurements at a single wavelength. In the present work we studied the gelation mechanism for chemical gels obtained from experiments that have been carried out with acrylamide (AAm) and N,N0-methylenebis (acrylamide) (Bis) as base materials for chemical gel formation in water and with cross-linker. The transmitted light intensity was measured for various wavelengths from 440 nm to 690 nm during the gelation process. The data are modeled by the epidemic SIR process. The results indicate that the gelation processes obtained from the same Bis and water contents observed at different wavelengths obey different SIR models. This observation is explained by the scattering of light of different wavelengths depending on the sizes of the micro-gels formed.

Wax deposition modeling in oil-water stratified pipe flow

Wax deposition in oil-water stratified flow is commonly encountered onshore and offshore oil production pipe systems, and typically reduces transportation capacity of oil. The accurate predicted model of wax deposition has becomes an indispensable approach to design effective remediation strategies. However, a reliable mechanistic model for wax deposition prediction in oil-water two-phase stratified pipe flow is lacking to validate the deposition process. In this work, a three-dimensional (axial, radial, and angular) robust wax deposit model for oil-water stratified circular pipe flow was developed. The model of formation of a gel deposit based on the first principles of rheology was developed, associated with the results obtained from hydrodynamics and heat/mass transfer simulations. The predictions for wax deposition are found to compare satisfactorily with experimental data with two different oils for single phase and four different water cuts for oil-water stratified pipe flow. It can be seen from the wax gelation mechanism that an increase in water cut can help to reduce the wall/oil-deposit interface shear stress, thereby leading to an increase in the degree of gelation as well as the deposit rate. Furthermore, a local deposit analysis in the circumferential direction was conducted, for water cut 75% and total flow rate 5 m 3 /h, which provided insights to understand that the thickness on pipe wall was roughly uniformly distributed locates near the top of the pipe and the nearer the position gets close to two points, where the oil-water interface contacts the inner wall, the deposition thickness quickly dropped to 0. It was attributed to the fact that a roughly uniformly thickness far away from the oil-water interface contact the inner wall resulted in the slowly changes temperature along the circumferential pipe wall wetted by oil.

Engineering Hydrogels for Modulation of Dendritic Cell Function.

Dendritic cells (DCs), the most potent antigen-presenting cells, are necessary for the effective activation of naïve T cells. DCs encounter numerous microenvironments with different biophysical properties, such as stiffness and viscoelasticity. Considering the emerging importance of mechanical cues for DC function, it is essential to understand the impacts of these cues on DC function in a physiological or pathological context. Engineered hydrogels have gained interest for the exploration of the impacts of biophysical matrix cues on DC functions, owing to their extracellular-matrix-mimetic properties, such as high water content, a sponge-like pore structure, and tunable mechanical properties. In this review, the introduction of gelation mechanisms of hydrogels is first summarized. Then, recent advances in the substantial effects of developing hydrogels on DC function are highlighted, and the potential molecular mechanisms are subsequently discussed. Finally, persisting questions and future perspectives are presented.

Effect of internal and external gelation on the physical properties, water distribution, and lycopene encapsulation properties of alginate-based emulsion gels

It is challenging to incorporate lycopene, a strongly hydrophobic nutraceutical, into functional foods because of its low water-solubility and poor bioaccessibility. In this study, we therefore examined the potential of alginate-based emulsion gels to encapsulate and deliver lycopene. Alginate can be gelled using either internal or external gelation mechanisms, but few studies have compared the advantages and disadvantages of these two approaches for producing emulsion gels. For this reason, we compared the structure, water distribution, water mobility, and simulated digestion of lycopene-loaded emulsion gels formed by gelling alginate within the aqueous phase using either the internal or external methods. The internal gelation method produced emulsion gels that contained smaller oil droplets, and had a higher hardness, water holding capacity, and freeze-thaw stability. Moreover, the internal gelation method led to emulsion gels that had a slightly higher lycopene bioaccessibility (36.1%) than the ones formed by the external gelation method (33.4%). These findings are important for optimizing the design and fabrication of emulsion gels suitable as delivery systems for nutraceuticals in the food industry.

Surfactant induced gelation of TEMPO-oxidized cellulose nanofibril dispersions probed using small angle neutron scattering.

In this work, we studied TEMPO-oxidized cellulose nanofibril (OCNF) suspensions in the presence of diverse surfactants. Using a combination of small angle neutron scattering (SANS) and rheology, we compared the physical properties of the suspensions with their structural behavior. Four surfactants were studied, all with the same hydrophobic tail length but different headgroups: hexaethylene glycol mono-n-dodecyl ether (C12EO6, nonionic), sodium dodecyl sulfate (SDS, anionic), cocamidopropyl betaine (CapB, zwitterionic), and dodecyltrimethylammonium bromide (DTAB, cationic). Contrast variation SANS studies using deuterated version of C12EO6 or SDS, or by varying the D2O/H2O ratio of the suspensions (with CapB), allowed focusing only on the structural properties of OCNFs or surfactant micelles. We showed that, in the concentration range studied, for C12EO6, although the nanofibrils are concentrated thanks to an excluded volume effect observed in SANS, the rheological properties of the suspensions are not affected. Addition of SDS or CapB induces gelation for surfactant concentrations superior to the critical micellar concentration (CMC). SANS results show that attractive interactions between OCNFs arise in the presence of these anionic or zwitterionic surfactants, hinting at depletion attraction as the main mechanism of gelation. Finally, addition of small amounts of DTAB (below the CMC) allows formation of a tough gel by adsorbing onto the OCNF surface.

Thermo-induced physically crosslinked polypeptide-based block copolymer hydrogels for biomedical applications.

Stimuli-responsive synthetic polypeptide-containing block copolymers have received considerable attention in recent years. Especially, unique thermo-induced sol-gel phase transitions were observed for elaborately-designed amphiphilic diblock copolypeptides and a range of poly(ethylene glycol) (PEG)-polypeptide block copolymers. The thermo-induced gelation mechanisms involve the evolution of secondary conformation, enhanced intramolecular interactions, as well as reduced hydration and increased chain entanglement of PEG blocks. The physical parameters, including polymer concentrations, sol-gel transition temperatures and storage moduli, were investigated. The polypeptide hydrogels exhibited good biocompatibility in vitro and in vivo, and displayed biodegradation periods ranging from 1 to 5 weeks. The unique thermo-induced sol-gel phase transitions offer the feasibility of minimal-invasive injection of the precursor aqueous solutions into body, followed by in situ hydrogel formation driven by physiological temperature. These advantages make polypeptide hydrogels interesting candidates for diverse biomedical applications, especially as injectable scaffolds for 3D cell culture and tissue regeneration as well as depots for local drug delivery. This review focuses on recent advances in the design and preparation of injectable, thermo-induced physically crosslinked polypeptide hydrogels. The influence of composition, secondary structure and chirality of polypeptide segments on the physical properties and biodegradation of the hydrogels are emphasized. Moreover, the studies on biomedical applications of the hydrogels are intensively discussed. Finally, the major challenges in the further development of polypeptide hydrogels for practical applications are proposed.

3D printing of thermosets with diverse rheological and functional applicabilities

Thermosets such as silicone are ubiquitous. However, existing manufacturing of thermosets involves either a prolonged manufacturing cycle (e.g., reaction injection molding), low geometric complexity (e.g., casting), or limited processable materials (e.g., frontal polymerization). Here, we report an in situ dual heating (ISDH) strategy for the rapid 3D printing of thermosets with complex structures and diverse rheological properties by incorporating direct ink writing (DIW) technique and a heating-accelerated in situ gelation mechanism. Enabled by an integrated Joule heater at the printhead, extruded thermosetting inks can quickly cure in situ, allowing for DIW of various thermosets with viscosities spanning five orders of magnitude, printed height over 100 mm, and high resolution of 50 μm. We further demonstrate DIW of a set of heterogenous thermosets using multiple functional materials and present a hybrid printing of a multilayer soft electronic circuit. Our ISDH strategy paves the way for fast manufacturing of thermosets for various emerging fields.

Morphological Control Over Gel Structures of Mixed Semiconductor-Metal Nanoparticle Gel Networks with Multivalent Cations.

In this work, the influence of two different types of cations on the gel formation and structure of mixed gel networks comprised of semiconductor (namely CdSe/CdS nanorods NR) and Au nanoparticles (NP) as well as on the respective monocomponent gels is investigated. Heteroassemblies built from colloidal building blocks are usually prepared by ligand removal or cross-linking, thus, both the surface chemistry and the destabilising agent play an essential role in the gelation process. Due to the diversity of the composition, morphology, and optical properties of the nanoparticles, a versatile route to fabricate functional heteroassemblies is of great demand. In the present work, the optics, morphology, and gelation mechanism of pure semiconductor and noble metal as well as their mixed nanoparticle gel networks are revealed. The influence of the gelation agents (bivalent and trivalent cations) on the structure-property correlation is elucidated by photoluminescence, X-ray photoelectron spectroscopy, and electron microscopy measurements. The selection of cations drastically influences the nano- and microstructure of the prepared gel network structures driven by the affinity of the cations to the ligands and the nanoparticle surface. This gelation technique provides a new platform to control the formation of porous assemblies based on semiconductor and metalnanoparticles.