Gel Formation Time Research Articles

Gel formation and its relaxation mechanism of shear-induced aqueous suspensions comprised of bentonite and heptaethylene oleyl ether

We considered the gelation and its relaxation mechanism of a shear-induced bentonite / heptaethylene oleyl ether (abbreviated as C18:1E7) aqueous suspension based on the analysis of Rheo-SALS. When bentonite / C18:1E7 aqueous suspension formed the shake-gel, the concentration of bentonite was greater than or equal to the critical concentration of c* = 1.3 wt% where hydrodynamic interactions occur. The relationship between the time ts when the shear thickening occurs and the bentonite / surfactant concentration (c - cs) can be described by the first-order reaction equation, and ts can be further reduced with the applied shearing.The gel formation time and the relaxation time were affected by the shear hysteresis. We found that the formation and the relaxation (breakdown) of gels comprising bentonite particles did not follow the same pathway. Thus, Shear induced gel formation is due to the percolation transition by the infinite network structure in which the anisotropic orientation of bentonite particles grows. In contrast, the relaxation (breakdown) of the gel proceeds by the isotropic diffusion of individual bentonite particles forming the network structure.

Thermosensitive Chitosan-β-Glycerophosphate Hydrogels as Targeted Drug Delivery Systems: An Overview on Preparation and Their Applications.

Today, with the advances in technology and science, more advanced drug delivery formulations are required. One of these new systems is an intelligent hydrogel. These systems are affected by the environment or conditions that become a gel, stay in the circumstance for a certain period, and slowly release the drug. As an advantage, only a lower dose of the drug is required, and it provides less toxicity and minor damage to other tissues. Hydrogels are of different types, including temperature-sensitive, pH-sensitive, ion change-sensitive, and magnetic field-sensitive. In this study, we investigated a kind of temperature-sensitive smart hydrogel, which has a liquid form at room temperature and becomes gel with increasing temperature. Chitosan-β-glycerophosphate hydrogels have been researched and used in many studies. This study investigates the various factors that influence the gelation mechanism, such as gel formation rates, temperature, pH, time, and gel specificity. Hydrogels are used in many drug delivery systems and diseases, including nasal drug delivery, vaginal drug delivery, wound healing, peritoneal adhesion, ophthalmic drug delivery, tissue engineering, and peptide and protein delivery. Overall, the chitosan-β-glycerophosphate hydrogel is a suitable drug carrier for a wide range of drugs. It shows little toxicity to the body, is biodegradable, and is compatible with other organs. This system can be used in different conditions and different medication ways, such as oral, nasal, and injection.

Spectral and thermal analysis of aromatic diamines and anhydrides cured chalcone moiety containing epoxy resin of (2E,6E)-bis(4-hydroxybenzylidene)cyclohexanone

Chalcone moiety containing epoxy resin of (2E,6E)-bis(4-hydroxybenzylidene)cyclohexanone (EBHBC) was cured at 150 °C by using 4,4′-dimethyldiphenylmethane (DDM), 4,4′-diaminodiphenylsulphone (DDS), 4,4′-diaminodiphenylether (DDE), p-phenylenediamine (PDA), 1,2,3,6-tetrahydrophthalicanhydride (THPA), maleic anhydride (MAH) and pyromelliticdianhydride (PMDA). Aromatic diamines cured EBHBC took little longer gel formation time than those of anhydrides cured EBHBC. Sol–gel analysis of cured resins was carried out in DMF at room temperature. Aromatic diamines and anhydrides cured EBHBC showed 4.2–15.6% and 2.4–7.5% sol fractions; and 84.4–95.8% and 92.5–97.6% gel fractions, respectively. DSC exothermic transitions supported curing of EBHBC, while endothermic transition supported decomposition of cured resin as supported by TGA. Aromatic diamines and anhydrides cured EBHBC are thermally stable up to 270–305 °C and 162–316 °C, respectively, and followed single-step degradation reactions except EBHBC-MAH. Aromatic diamines (35–58%) and anhydrides (46–56%) cured EBHBC showed considerably large residues at 700–800 °C. Aromatic diamines and anhydrides cured EBHBC showed, respectively, 30–52% and 32–41% residues at 700–800 °C. Cured EBHBC resins followed either apparently first order or one and half order degradation kinetics. Cured EBHBC resins showed different Ea and A values indicating inherent structural effect of different hardeners used.

THE STUDY OF THE DEPENDENCE OF THE RHEOLOGICAL PROPERTIES OF GELFORMING COMPOSITIONS ON THE CRACK OPENING WHEN MODELING THEIR FLOW ON A ROTATIONAL VISCOMETER

The current period of oil production is characterized by the deterioration of the structure of oil reserves because of high water cut of the product and low oil production rates. To reduce the increased water cut, repair and insulation works are often performed. This implies in the injection of cross-linked polymer systems or the treatment of the bottom hole formation zone with polymer-gel systems. This problem is especially relevant for fractured reservoirs, which are often represented by carbonate rocks. This article is devoted to the study of the dependence of the rheological properties of gel-forming compositions on the crack opening in carbonate reservoirs. The relevance of the work relies on the rapid involvement in the development of oil fields with carbonate reservoirs which is complicated by a large number of cracks of various sizes. The types of fractured reservoirs, the development features of each type, as well as complications in the hydrocarbon production from the fracturedpore structure of the reservoir were described. The research also pointed methods and technologies for limiting water flow in cracks or pores of high permeability. The rheological properties of fluids when moving inside pores and cracks were reported. The dependence of changes in the rheological properties of the composition for limiting water inflow based on carboxymethylcellulose on the size of pores, caverns and cracks were presented. The physics of movement and formation of gel inside the fractured reservoirs, which will allow predicting changes in the gel formation time and plastic strength for each object individually was described. According to this study, it is possible to use the features of the rheological properties of gel-forming compositions to increase the efficiency of the use of water-proofing technologies for producing wells, or to align the injectivity profile of injection wells.

Controlled gel research: the effect of ethanol for delaying the polycondensation of tetraethyl orthosilicate-dimethyldiethoxysilane

In this study, the effect of ethanol for delaying the polycondensation of silanol in the co-hydrolysis-condensation of tetraethyl orthosilicate-dimethyldiethoxysilane was first explored and demonstrated by varying the amount of ethanol under low-water content and acid-catalyzed. On the basis of this, the controllability of the sol-gel process is realized, and the calculation formula of the gel formation time is provided. The experiment shows that the storage gel time and the reaction gel time are extended from 75 h to at least 4584 h, or from 20 to 65 h with the increase of ethanol concentration, respectively. And we observed the microscopic process of solution-sol-gel transition by light transmission microscope. The sol-gel process established in this experiment gives a mechanism reference for future research.

Production of cheese from donkey milk as influenced by addition of transglutaminase

Donkey milk is characterized by low contents of total solids, fat, and caseins, especially κ-casein, which results in formation of a very weak gel upon renneting. The objective of this study was to evaluate the effect of fortification of donkey milk with microbial transglutaminase (MTGase) for cheesemaking in relation to different enzyme addition protocols (patterns, PAT). Four independent trials were performed using MTGase (5.0 U/g of milk protein) according to the following experimental patterns: control (no MTGase addition); MTGase addition (40°C) 15 min before starter inoculation (PAT1); addition of MTGase to milk simultaneously with starter culture (40°C) (PAT2); and MTGase addition simultaneously with rennet (42°C) in acidified milk (pH 6.3) (PAT3). Evolution of pH during acidification, cheesemaking parameters, and proximal composition and color of cheese at 24 h were recorded. The protein fractions of cheese and whey were investigated by urea-PAGE and sodium dodecyl sulfate-PAGE. Addition of MTGase had no significant effect on moisture, protein, fat, or cheese yield. The addition of MTGase with rennet (PAT3) improved curd firmness compared with the control. Among the different patterns of MTGase addition, PAT3 reduced gel formation time, time between rennet addition and cheese molding, and weight loss of cheese at 24 h. The PAT3 treatment also resulted in the lowest lightness and highest yellowness color values of the cheese. Sodium dodecyl sulfate-PAGE of cheeses revealed that MTGase modified the protein pattern in the high-molecular-weight zone (range 37-75 kDa) compared with the control. Of the MTGase protocols, PAT3 showed better casein retention in cheese, as confirmed by the lanes of α- and β-caseins in the electropherogram of the whey, which was subtler for this protocol. In conclusion, MTGase may be used in cheese production from donkey milk to improve curd firmness; MTGase should be added simultaneously with the rennet.

Preparation and pH‐Dependent Properties of Hydrogels Based on Acidic Copolymers with PEG Side Chains and α‐Cyclodextrin

AbstractA variety of differently structured PEG‐based polymers can form physically cross‐linked PEG hydrogels with α‐cyclodextrin. The polymer structures strongly influence the properties of the hydrogel and its formation. Four different copolymers of methoxy PEG methacrylate and methacrylic acid are used together with α‐cyclodextrin to study hydrogel formation speed and gel strength. The hydrogels are formed within 1–25 min, and the formation process is examined in situ by dynamic light scattering. The gel formation time is pH dependent due to the methacrylic acid present in the polymers. The gel strength examined by texture analyzer also depends on the composition and pH. With prior mechanical destruction, all hydrogels are dissolvable in an excess of water, being a useful feature for an in vivo usage. By analyzing the structures of the hydrogels with confocal light microscopy (laser scanning confocal microscopy) and scanning electron microscope (SEM) after freeze etching, the different hydrogel structures can be observed.

Сферопластики пониженной плотности на основе полых фенолформальдегидных микросфер и эпоксидиановой смолы

In this article the physical-mechanical, thermal and electrical properties of spheroplastic based on epoxy resin ED-20 and hollow phenol-formaldehyde microspheres were studied. The samples were obtained by mixing an epoxy resin, cured with polyethylene polyamine, with hollow phenol-formaldehyde microspheres, poured into a mold and then cured at room temperature. The influence of the filler on the kinetics of the interaction of epoxy oligomer and aliphatic polyamine was studied. The effect of reducing the time of gel formation may occur due to the possible presence of reactive groups on the surface of microspheres. The experiments showed that the introduction of hollow phenol-formaldehyde microspheres in General leads to a slight decrease in the gel formation time. It is established that the introduction of hollow microspheres into the composition leads to a decrease in the density of the finished composition. The impact strength of spheroplastic was determined in accordance with GOST 4647-2015 "Method of Charpy impact strength determination" (ISO 179-1: 2010, NEQ). The introduction of hollow microspheres into the composition leads to a change in the impact strength of the composition in the direction of its decrease. A similar trend is observed in the study of the strength in the separation from the substrate of different materials. The coefficient of thermal conductivity was determined in a stationary mode on the device ITP-MG4"100" GOST 7076-99 "Method for determining the thermal conductivity and thermal resistance in a stationary thermal regime." Studies have shown that an increase in the content of hollow microspheres in the composition to 15% leads to a gradual decrease in the thermal conductivity coefficient to 0.74 W/m∙K. The studied materials can be used as thermal insulation materials and for the manufacture of products used in various fields of science and technology.

Method for Determining the Rational Regimes of Curing Products from Polymer Composite Materials

The results of the evaluation of the technological and thermophysical properties of the epoxy binder in the initial state and after its curing are presented. As a binder used on the basis of epoxy-dianova brand ED-20 and triethylenetetramine (TETA). The time and temperature of gel formation are determined by the method of dynamomechanical analysis, depending on the speed of the heating process. The activation energy is estimated. The values of heat capacity and thermal conductivity were determined experimentally, depending on the degree of curing. The established regularities made it possible to develop a method for determining rational heating regimes taking into account the kinetics of gelling.

Fundamentals of alkali-silica gel formation and swelling: Condensation under influence of dissolved salts

The current theory of ASR gel formation in concrete between silicic acid anions with cations and is unable to explain the differences in concentration required for gel formation between e.g. potassium and sodium or the effect of calcium on the gel formation. In this paper, a new gelation mechanism is explained by means of a condensation between silicic acid anions. The role of salts on the ASR gel formation and gel time is described by their charge screening capacity of the silicic acid, resulting in the decreasing concentration range for gelation: Ca<Mg<Cs<Rb<K<Na<Li. A Cation Gelling Strength (CGS) is defined to assess the cation strength when different cations are present. Silica gel formation will moreover in many cases form a calcium silica precipitate rather than a gel that will be difficult to distinguish from CSH formed during hydration.

Characterization of Organogel Prepared from Rice Bran Oil with Cinnamic Acid

Cinnamic acid (CA) was added to rice bran oil (RBO) at concentrations range from 2 to 12% (w/w) to prepare functional fat-like organogel. The oil binding capacity and gel formation time of the obtained organogels were determined. The results showed that the oil binding capacity was increased and the gel formation time was significantly (p < 0.05) decreased with the increase in concentration of CA up to 10% (w/w). Based on these results, organogels prepared from RBO with 6, 8, and 10% CA (w/w) were chosen and subjected to further characterization analyses. The microscopy analysis showed different gel network structures and crystalline behavior for the organogels prepared with varying concentrations of CA. The rheological and thermal properties of the organogel were improved with the increase in CA concentration up to 10% (w/w). The X-ray diffractometer and Fourier Transform Infrared spectroscopy analyses indicated that the gel network formed based on crystalline of CA and physical entanglements among the organogel components. In addition, the organogel of RBO with 10% CA (w/w) showed a uniform and homogenized structure during storage at 5 °C for 28 days compared to the organogels prepared with 6 and 8%. Therefore, it can be suggested that cinnamic acid is a good organogelator for preparing functional fat-like organogel from rice bran oil.

Self-assembly behaviors of dibenzylidene sorbitol hybrid organogels with inorganic silica.

Molecular interactions, rheological behaviors and microstructures of 1,3:2,4-dibenzylidene-d-sorbitol (DBS)/poly(ethylene glycol) (PEG) organogel-inorganic silica hybrid materials are discussed in this study. DBS can dissolve in low-molecular-weight PEG to form organogels. The self-assembly behavior of these organogels was significantly influenced by the addition of the inorganic silica. The π interactions between the phenyl rings of DBS were not influenced by silica addition; however, the addition of silica affected the intermolecular hydrogen bonding of DBS, which interacts with PEG. The silica more likely interacted with PEG and decreased the intermolecular interactions between DBS and PEG, which resulted in an increase in the self-assembly of DBS. Therefore, the gel formation time and gel dissolution temperature increased as the amount of silica increased, as determined by dynamic rheological instruments. In addition, these organogel systems were all found to exhibit spherulite-like textures under polarized optical microscopy. The addition of silica and the increased DBS self-assembly in PEG resulted in a higher self-assembly temperature of the organogels. The higher temperature resulted in the presence of fewer nucleation sites and larger spherulite sizes in these systems. Small-angle X-ray scattering results demonstrated lamellar packing in these spherulite-like morphologies. Furthermore, the organogels with silica affected the intermolecular hydrogen bonding between DBS and PEG to facilitate the self-assembly of DBS, which resulted in increased diameter sizes of the DBS nanofibrils, as observed using scanning electron microscopy. It was observed that the silica was entrapped within these nanofibrillar networks.

Synthesis and Characterization of CaO-SiO&lt;sub&gt;2&lt;/sub&gt;-MgO Bioactive Glass Produced by Sol-Gel

Bioactive glasses have widely used in biomedical applications such as bone filler due to their excellent biocompatibility, bioactivity and osteoconduction characteristics. In this work, a silicate-rich glass was synthesized by the sol-gel method with 60% SiO2 – 30%CaO – 10% MgO composition where fumed silica acts as the silica precursor. This new method was hypothesized to reduce the gel formation time, due to the high surface area of the fumed silica. In addition, this would presumably increase the nanoporosity of the glass. For comparison purposes, we used a glass of the same composition, but with the conventional silica precursor, tetraethyl orthosilicate (TEOS), through the sol gel method. Both were heat treated at 450°C. FT-IR analysis before and after heat treatment at 450°C showed the presence of nitrate groups, especially in the TEOS samples. This is consistent with the more hygroscopic aspect of those samples. The fumed silica samples had significantly less pronounced peaks corresponding to the nitrate groups, consistent with the more porous structure and the less hygroscopic aspect. The fumed silica samples indeed had a lower gelling time and showed similar results obtained by XRD and FT-IR analyses, showing that the use of fumed silica is viable and advantageous in the glass synthesis by the sol-gel process

Impact of Water on Rheological Behavior of Polyurethane Glues

Abstract Gluing of wood with great moisture content has challenge of water interaction with glue to give unwanted changes in glue properties and formed bond-line. Rheological measurements of polyurethane glues are sufficiently effective method to understand the polymer curing process and viscoelastic properties. Gel formation point is important parameter for a glue from the point of its application. When glue reaches the gel formation point, its viscosity drastically increases so that it could not properly wet the wood and it can result in poor bonds. One-component moisture curing polyurethane glues require water molecules for the polyadditional reaction. When water is involved in the curing reaction, it reacts with the isocyanate groups of glue and can lead to the formation of excessive carbon dioxide and thus can lead to glue penetration out of bond-line, additional backpressure. The dynamic viscoelastic parameters such as complex dynamic viscosity (ή), phase angle (δ), elastic storage modulus (G”), the viscous loss modulus (G”) of two kinds of polyurethane glues depending on added water amount (from 0.9% to 10.0%) at a constant frequency and deformation (oscillation mode) were determined using rheometer. The aim of the present study was to investigate impact of added water on rheological behavior of polyurethane glues. At the end of this study it was concluded that tested glues indicated various behavior depending on chemical composition and added water content. Gel formation point is higher in case of GlueI. However, gel formation time was higher in case of GlueII and was not dependent on added water content. Gel formation time was faster for GlueII. Nevertheless, faster formed gel is stronger than longer formed gel of GlueI.

Effect on Gel Formation Time of Adding Topical Ophthalmic Medications to ReSure Sealant, an In Situ Hydrogel.

The purpose of this study was to describe the gel formation times of ReSure(®) Sealant, an in situ hydrogel approved to seal cataract surgery incisions, when commercially available topical medications are mixed with the sealant. In this experimental laboratory study, the commercial product, ReSure Sealant, was used as per the product insert. Two drops of diluent were mixed with the polymer and time to gel formation was measured. Following this, various commercial antibiotic, nonsteroidal anti-inflammatory drug and steroid drops were used in substitution of one of the drops of the diluent. Combinations of 2 medications were also tested. Each condition was performed in triplicate and the mean gel time was calculated. The addition of bromfenac slightly reduced mean gel time from 19 s (ReSure alone) to 13 s. All other medications, including moxifloxacin, gatifloxacin, ofloxacin, ciprofloxacin, loteprednol etabonate, prednisolone acetate, dexamethasone, ketorolac, and nepafenac, increased mean gel time, ranging from 49 s to >120 s. The addition of bromfenac to moxifloxacin, ofloxacin, or gatifloxacin reduced their mean gel times from ≥105 s to 18-29 s. Certain medications, specifically bromfenac, may not substantially alter time to gel formation of ReSure Sealant when added to the hydrogel. In fact, bromfenac added to moxifloxacin, ofloxacin, or gatifloxacin reduced gel formation time to acceptable levels. All other medications and combinations of medications added to ReSure Sealant produced unacceptably long gel times to be used routinely. Clinical studies may be considered based on these results to assess the safety and efficacy of this strategy.

In vitro study of the role of thrombin in platelet rich plasma (PRP) preparation: utility for gel formation and impact in growth factors release

The use of PRP has been studied for different fields, with promising results in regenerative medicine. Until now, there is no study in the literature evaluating thrombin levels in serum, used as autologous thrombin preparation. Therefore, in the present study we evaluated the role played by different thrombin concentrations in PRP and the impact in the release of growth factors. Also, different activators for PRP gel formation were evaluated. Thrombin levels were measured in different autologous preparations: serum, L-PRP (PRP rich in leukocytes) and T-PRP (thrombin produced through PRP added calcium gluconate). L-PRP was prepared according to the literature, with platelets and leukocytes being quantified. The effect of autologous thrombin associated or not with calcium in PRP gel was determined by measuring the time of gel formation. The relationship between thrombin concentration and release of growth factors was determined by growth factors (PDGF-AA, VEGF and EGF) multiplex analysis. A similar concentration of thrombin was observed in serum, L-PRP and T-PRP (8.13 nM, 8.63 nM and 7.56 nM, respectively) with a high variation between individuals (CV%: 35.07, 43 and 58.42, respectively). T-PRP and serum with calcium chloride showed similar results in time to promote gel formation. The increase of thrombin concentrations (2.66, 8 and 24 nM) did not promote an increase in growth factor release. The technique of using serum as a thrombin source proved to be the most efficient and reproducible for promoting PRP gel formation, with some advantages when compared to other activation methods, as this technique is easier and quicker with no need of consuming part of PRP. Noteworthy, PRP activation using different thrombin concentrations did not promote a higher release of growth factors, appearing not to be necessary when PRP is used as a suspension.

Effect of protein structure on water and fat distribution during meat gelling

Emulsion-type sausages were produced, at 80°C for either 0, 10, 20 or 30min, using homogeneous Taihu pork batters. Low-field nuclear magnetic resonance (LF-NMR), with or without deuterium oxide (D2O) substitution, evaluated the proton mobility states related to both water and fat molecules, or fat molecules only, respectively, in the sausage samples, during heat-induced gelation. The decreasing trend in the area proportion of main peak T21, reflected a tighter gel structure in emulsion-type sausages. Raman spectra (400–3600cm–1) revealed decreased α-helix, but increased β-sheet, β-turns and random coil contents, during the gelling process. Moreover, principal component analysis (PCA) showed significant correlations between secondary protein structures with distribution of water and fat in the gel matrix. Furthermore, this study established the relationship of water and fat protons mobility with changes in secondary protein structures, and described the critical time of gel formation in emulsion-type pork sausages.

Enamine‐Based Hydrophilic Dynamic Covalent Polymer Networks: Effects of pH, and Copolymer Composition and Concentration on the Aqueous Swelling Degrees and the Gel Formation Times

SummaryIn this work, we explore the formation in water of dynamic covalent polymer networks cross‐linked via enamine groups. The polymer networks resulted from the combination of pairs of chemically complementary hydrophilic statistical copolymers, synthesized via reversible addition‐fragmentation chain transfer polymerization, and bearing a primary amine group comonomer on the one hand, and acetoacetate groups on the other; the main comonomer in both statistical copolymers was poly(ethylene glycol) methacrylate methyl ether. In this preliminary investigation, the gel formation time and the equilibrium swelling degrees in water were measured at different pH values, different copolymer concentrations, and for different copolymers. It was found that the gel formation time was reduced as the copolymer concentration was increased, and as the contents in amine and acetoacetate units in the copolymers was increased; furthermore, a minimum in the gel formation time was observed at pH 8.0. The effect of these three factors on the equilibrium aqueous swelling degrees was found to be much weaker than on gel formation time.

Processing and properties of spray-applied, 100% solids polyurethane coatings from rapeseed oil polyols

Rigid polyurethane (PU) coatings were obtained from rapeseed oil (RO), triethanolamine (TEA), diethanolamine, and glycerol polyols. The dynamic mechanical analysis of PU coatings showed that the β-transition process occurs at −60°C for these PU networks. At 20°C, the tensile storage modulus (E′) is higher for those PU networks that are characterized with higher cohesive energy density (CED). There is a good correlation between the theoretical molecular weights between two crosslinking points (Mc) of the PU network and Mc that has been calculated from E′ based on the ideal rubber theory. PU coatings from a RO/TEA polyol and polymeric 4,4′-methylene diphenyldiisocyanate (MDI) were sprayed using a Graco Reactor E-10 industrial spraying machine with a volume ratio of the components A:B = 1.0:1.0. Eco-friendly volatile organic compounds-free, 100% solids, fast-curing two pack (2 K) PU coating compositions were formulated. The kinetics of gel formation was studied for PU coatings from RO/TEA, chain extenders, and polymeric MDI under adiabatic conditions; the temperature range was from 10 to 50°C. It was found that gel formation occurs with activation energy (Ea) 26.56–33.43 kJ/mol. When a PU coating is spray-applied on a substrate under nonadiabatic conditions, the gel formation time of the coating is not significantly influenced by the temperature of the components in the range 20–50°C.

Sustained release drug delivery using supramolecular hydrogels of the triblock copolymer PCL–PEG–PCL and α-cyclodextrin

Supramolecular hydrogels (SMGel) have attracted much attention as a drug and gene delivery system in recent years. In this study, SMGels based on the tri-block copolymer of poly-e-caprolactone–polyethylene glycol–poly-e-caprolactone (PCL–PEG–PCL) and α-cyclodextrin (α-CD) were prepared and evaluated for the delivery of two model drugs, naltrexone hydrochloride and vitamin B12. Tri-block copolymers were synthesized easily in 15 min by ring-opening polymerization using the microwave irradiation technique, and their structures were determined by gel permeation chromatography and nuclear magnetic resonance methods. SMGels composed of various concentrations of the copolymer and α-CD were prepared and characterized for their rheological behaviour, their gel formation time and in vitro drug release profile. The results indicated that copolymers with a PCL to PEG ratio of 1:4 are suitable for SMGel preparation. The most viscose system with good syringeability was prepared by mixing 12 % wt α-CD and 10 % wt of copolymer. The gelation was found to occur within a minute after mixing. The viscosity of the hydrogel systems was determined as a function of shear rate. Finally, in vitro B12 release through the hydrogel systems was studied. Up to 80 % of Vitamin B12 was released through this system during a period of 20 days. Rheological evaluation revealed that the hydrogel has shear thinning properties, and the system regained its ground rheological state in a time dependent manner. Polymer concentration did not affect the drug release profiles. Finally, it was concluded that such systems are appropriate drug delivery systems due to their ability to provide a controlled drug release profile and their shear thinning thixotropic behaviour, which makes them syringeable and injectable.