Critical Gelation Concentration Research Articles

Self-assembly of amphiphilic aryl-squaramides in water driven by dipolar π-π interactions.

Squaramides are versatile compounds with a great capacity to interact via non-covalent interactions and therefore of interest for the development of supramolecular systems and functional materials. In the present work, a new series of aryl-squaramide amphiphiles (1-5) were prepared to form supramolecular polymers in water. Interestingly, only compounds 1 and 2 that contain electron-deficient aryl groups are capable of forming hydrogels (∼10-2 M) upon treatment with a base (NaOH or PBS). The aggregation behaviour of 1 and 2 was studied by static light scattering, UV-Vis, 1H NMR, FT-IR, and atomic force microscopy, and it was found that these compounds aggregate forming well-defined 1D nanofibers below the critical gelation concentration (<10-3 M). Moreover, the combination of these experiments with 1D and 2D NMR studies and theoretical calculations revealed that 1 and 2 self-assemble via an unprecedented interaction motif showing dipolar π-π interactions between the squaramide rings and the 4-nitrophenyl or 3,5-bis(trifluoromethyl)phenyl rings of 1 and 2, respectively. Such kinds of assemblies are stabilized by the compensation of the dipole moments of the stacked molecules. This interaction mode contrasts with those typically driving squaramide-based assemblies based on either hydrogen bonds or antiparallel stacking. We believe that this interaction motif is of interest for the design and development of new squaramide nanomaterials with free hydrogen bonding groups, which might be useful in drug delivery applications.

Triazole Linked N-Acetylglucosamine Based Gelators for Crude Oil Separation and Dye Removal.

Marine oil-spills have a long-lasting impact on the environment; therefore, it is a major concern in the scientific community to find a solution for remediation. Recently, phase selective organo-gelators emerged as potential materials for removal of oil from water through selective gelation. Herein, we report synthesis of a series of C-6 triazole linked N-acetylglucosamine derivatives, among which three have shown excellent selective gelation of organic solvents, diesel, petrol, and crude oils in water and seawater. We have studied phase selective gelation against different API grade crude oils (from light to heavy), and the gelation was achieved using nontoxic carrier solvent at room temperature in less than 15 min, and gelators were found useful for recovering crude oils. Critical gel concentration (CGC) of crude oil gelators was found to be 2.3-12% (w/v). The variable temperature NMR and FTIR experiments reveal that intermolecular hydrogen bonding was responsible for gel formation. Furthermore, a gelator was utilized for selective dye removal from water.

Pyrene‐based fluorescent supramolecular hydrogel: scaffold for nanoparticle synthesis

AbstractThe present work illustrates the design and development of pyrene‐based fluorescent supramolecular hydrogel consisting of l‐phenylalanine residue as the linker and ethyleneoxy unit with free primary amine at C‐terminal. The gelator efficiently immobilized aqueous media, and the critical gelation concentration (CGC) was found at 2.8 mM of the compound. Interestingly, the presence of pyrene moiety in the structure made the hydrogel intrinsically fluorescent. The self‐aggregation properties of the thermo‐reversible hydrogel were investigated using different microscopic and spectroscopic techniques such as high‐resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy, and X‐ray diffraction (XRD) spectroscopy. A balanced participation of noncovalent interactions like hydrogen bonding, π‐π stacking, and van der Waals interaction was identified as the driving force for gelation. Rheological experiments were performed to confirm the viscoelastic nature of the prepared hydrogel. Furthermore, primary amine (─NH2) group of hydrogelator was utilized for the in situ synthesis of silver nanoparticles (AgNPs) within the soft material under sunlight in the absence of any external reducing and stabilizing agent.

Widely Adaptable Oil-in-Water Gel Emulsions Stabilized by an Amphiphilic Hydrogelator Derived from Dehydroabietic Acid.

A surfactant, R-6-AO, derived from dehydroabietic acid has been synthesized. It behaves as a highly efficient low-molecular-weight hydrogelator with an extremely low critical gelation concentration (CGC) of 0.18 wt % (4 mm). R-6-AO not only stabilizes oil-in-water (O/W) emulsions at concentrations above its critical micelle concentration (cmc) of 0.6 mm, but also forms gel emulsions at concentrations beyond the CGC with the oil volume fraction freely adjustable between 2 % and 95 %. Cryo-TEM images reveal that R-6-AO molecules self-assemble into left-handed helical fibers with cross-sectional diameters of about 10 nm in pure water, which can be turned to very stable hydrogels at concentrations above the CGC. The gel emulsions stabilized by R-6-AO can be prepared with different oils (n-dodecane, n-decane, n-octane, soybean oil, olive oil, tricaprylin) owing to the tricyclic diterpene hydrophobic structure in their molecules that enables them to adopt a unique arrangement in the fibers.

Mussel-Inspired Adhesive Polydopamine-Functionalized Hyaluronic Acid Hydrogel with Potential Bacterial Inhibition.

Hyaluronic acid (HA)‐based hydrogels have been receiving increasing attention for wound management. However, pure HA hydrogels usually exhibit weak mechanical strength and poor anti‐infection. Herein, a hybrid HA‐based hydrogel (PDA‐HA) comprised of polydopamine (PDA) and thiolated hyaluronic acid (HA‐SH) is developed based on the Michael addition reaction. The introduction of PDA into HA hydrogel can decrease the critical gel concentration, improve the cell affinity and tissue adhesion, as well as endow the hydrogel with efficient free‐radical scavenging ability. Combining the merits of good biocompatibility and moist environment from HA hydrogel with excellent tissue adhesiveness and free radical scavenging capability from PDA, this cross‐linked PDA‐HA hybrid hydrogel exhibits great potential for creating antimicrobial wound medical dressings.

Self-Healable, Fast Responsive Poly(ω-Pentadecalactone) Thermogelling System for Effective Liver Cancer Therapy.

A polyurethane based thermogelling system comprising poly(ω-pentadecalactone) (PPDL), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG), termed as PDEP, was synthesized. The incorporation of PPDL lowers critical micelle concentration (CMC) as well as critical gelation concentration (CGC) of the novel copolymers compared to commercial Pluronic® F127. The thermogels showed excellent thermal stability at high temperature up to 80°C, fast response to temperature change in a time frame of less than second, as well as remarkable self-healing properties after being broken at high strain. In vitro drug release studies using docetaxel (DTX) and cell uptake studies using doxorubicin (DOX) show high potential of the hydrogel as drug reservoir for sustainable release profile of payloads, while the in vivo anti-tumor evaluation using mice model of hepatocellular carcinoma further demonstrated the significant inhibition on the growth of tumor. Together with its excellent biocompatibility in different organs, the novel PDPE thermogelling copolymers reported in this work could potentially be utilized as in situ-forming hydrogels for liver cancer therapy.

Synthesis and Self‐assembly of a Helical Polymer Grafted from a Foldable Polyurethane Scaffold

Herein a polyurethane graft poly-l-glutamate amphiphilic copolymer was synthesized from a polyurethane (PU)-based macro-initiator (containing pendant primary amine groups) through the ring opening polymerization of N-carboxy anhydride of γ-benzyl-l-glutamate (BLG-NCA). On average, twenty two l-glutamic acids were grafted from each amino group which was pendant on the polyurethane chain with 10 repeating units. The grafted polymer (PU-PP-1) exhibits self-assembly to produce a hydrogel in a wide pH window ranging from pH 5.0 to 8.0 with a critical gelation concentration (CGC) of 5.0 wt % (w/v) at pH 7.4. Furthermore, circular dichroism study revealed the transition of the α-helix to a random coil upon increasing the pH. Due to the protonation of side chains at pH 4.0, PU-PP-1 adopted an α-helical conformation whereas at pH >8.0 the side-chain carboxylic acid groups of the PLGAs were ionized, leading to the formation of an extended random coil conformation as a result of charge repulsion. Conformational switching was also supported by FTIR spectroscopy.

A monopyrrolotetrathiafulvalene based naphthalimide tailored organogelator with stimuli responsive properties and absorption for rhodamine B

A novel 1,8-naphthalimide functionalized monopyrrolotetrathiafulvalene (MPTTF) derivative had been established as a low molecular weight supramolecular gelator. Supramolecular organogels could be obtained in solvents with different polarity through the heating-cooling process. Further addition of 7,7,8,8-tetracyanoquino-dimethane (TCNQ) to the supramolecular gel systems via the electron donor-acceptor interaction between the MPTTF and TCNQ, especially in polar solvents, could fabricate charge-transfer (CT) complex gels at relatively lower critical gelation concentrations. Interestingly, the self-assembly mode of the CT complexes was closely related to the type of solvents. As expected, due to the dynamic and reversible nature of the non-covalent interactions, the resultant gels exhibited external stimuli-responsiveness to different parameters, including temperature, chemical redox reagent and acid-base. However, the redox stimulus response of the gels depended on the polarity of the solvents, and the reversible gel-sol transformation could be achieved in nonpolar solvent, such as benzene. Moreover, the prepared gels showed irreversible gel-sol transitions on successively triggering with trifluoroacetic acid and triethylamine unless washed with water. Importantly, the original and CT complex gels could effectively remove the cationic rhodamine B dye from water.

Benzohydrazide Derivatives: Gelation and Application in Oil Spill Recovery

The synthesis and gelation properties of a series of organogelators containing a benzohydrazide unit and two alkoxy chains(oBn) were reported herein. oBn(n=8, 10, 12) could form stable gels in commercial fuels(e.g., diesel), which were characterized by low critical gelation concentrations(CGCs) and good mechanical properties (G′>105 Pa). The gelation process was further studied by field-emission scanning electron microscopy(FE-SEM), Fourier transform infrared spectroscopy(FTIR) and X-ray diffraction(XRD), etc. It was demonstrated that in these organogels, molecules self-assembled into fibrils 3D-network, where hydrogen bonding, van der Waals force and π-π interaction were confirmed as the driving forces. As compounds oBn(n=8, 10, 12) show very good gelation properties in diesel, their applications in oil spill treatment have also been tested. It was found that oBn could achieve rapid (<30 s) and effective oil removal at room temperature, being good candidates for oil spill treatment in the future. Also, the removal efficiency could be as high as 95%.

Design and physicochemical properties of long and stiff fatty low molecular weight oleogelators

Stearic acid and nine other derived long and fatty low molecular weight oleogelators were tested to gelate two different vegetable and edible oils, liquid paraffin and methyl oleate. In these liquids, among all gelator candidates, three of them expressed remarkable Critical Gelation Concentration (CGC) values found in a range of 0.6 and 2 wt% Their gelation ability were apparently dependent on their intrinsic molecular structure and evolved function of their lipophilic balance. To understand the phenomena reported here, microscopic observations of the gel samples were carried out to study the gel texture. The FT-IR analysis of each sample also afforded detailed information about the molecular assembly of the additives and their potential role in the host liquids. Differential Scanning Calorimetry (DSC) measurements demonstrated the potential for our best oleogelators candidates to form strong gels in the hydrophobic liquids, and the possible direct interactions with the TAGs included in the edible oils. The study of the viscoelastic behavior confirmed also the importance of two long alkyl chains grafted on a small and rigid spacer and the need of a non-negligible lipophilic level of these gelators to get a strong and stable gel at the lower concentrations.

Effect of Core Cross-linking on the Physical Properties of Poly(dimethylsiloxane)-Based Diblock Copolymer Worms Prepared in Silicone Oil

A trithiocarbonate-capped poly(dimethylsiloxane) (PDMS) precursor is chain-extended via reversible addition–fragmentation chain transfer dispersion polymerization of 2-(dimethylamino)ethyl methacrylate (DMA) in decamethylcyclopentasiloxane (D5) silicone oil at 90 °C. For a fixed mean degree of polymerization (DP) of 66 for the PDMS steric stabilizer block, targeting core-forming PDMA block DPs of between 105 and 190 enables the preparation of either well-defined worms or vesicles at a copolymer concentration of 25% w/w. The as-synthesized linear PDMS66–PDMA100 worms exhibit thermoresponsive behavior in D5, undergoing a worm-to-sphere transition on heating to 100 °C. Variable temperature 1H NMR spectroscopy indicates that this thermal transition is driven by reversible solvent plasticization of the PDMA cores. This change in copolymer morphology is characterized by transmission electron microscopy (TEM) studies, variable temperature dynamic light scattering and small-angle X-ray scattering experiments. Oscillatory rheology studies indicate that degelation occurs at 32 °C, but shear-induced polarized light imaging measurements suggest that full conversion of worms into spheres requires significantly higher temperatures (∼110 °C). 1,2-Bis(2-iodoethoxy)ethane (BIEE) is evaluated as a cross-linker for PDMS66–PDMAx diblock copolymer nano-objects in D5. This bifunctional reagent quaternizes the tertiary amine groups on the DMA residues within the worm cores, introducing cross-links via the Menshutkin reaction. TEM studies confirm that such covalently-stabilized worms no longer undergo a worm-to-sphere transition when heated to 100 °C. Kinetic studies performed on PDMS66–PDMA176 vesicles suggest that cross-linking requires approximately 13 h at 20 °C to ensure that these nano-objects remain intact when dispersed in chloroform, which is a good solvent for both blocks. Oscillatory rheology studies of a PDMS66–PDMA100 worm gel indicated that covalent stabilization using a BIEE/DMA molar ratio of 0.15 increased its dynamic elastic modulus (G′) by almost two orders of magnitude. Furthermore, such cross-linked worms exhibit a much lower critical gelation concentration (∼2% w/w) compared to that of the linear precursor worms (∼12% w/w).

Sustained release of ketorolac tromethamine from poloxamer 407/cellulose nanofibrils graft nanocollagen based ophthalmic formulations

There has been extensive utilization of poloxamer 407 (PM) for the delivery of various ophthalmic drugs aimed at efficient ophthalmic drug delivery approach for longer precorneal residence time along with acceptable bioavailability of drugs. We have studied the effect of nanocellulose grafted collagen (CGC) on the performance of in situ gels based on PM for the controlled in vitro release of Ketorolac Tromethamine (KT). CGC has shown great influence evident by the reduction in PM critical gelation concentration, increased gel strength, and prolonged the release of loaded drugs compared with the virgin PM gel. The engineered nanocomposite formulations established an anomalous diffusion mechanism along with a Fickian diffusion controlled drug release for 1.5 & 1.75 w/v% CGC reinforced PM. Hence, the synthesized in situ nanocomposites are potential candidates for ophthalmic drug delivery system.

OLEOGELS OF OLIVE OIL AND SOYBEAN OIL FOR TOPICAL DRUG DELIVERY: A COMPARATIVE ANALYSIS

Objective: The objective of the present investigation was to develop olive and soybean oil-based oleogels with Span 40 and/or Tween 80 (as gelator and/or surfactant) and determine the critical gelator concentration (CGC), characterise and compare the rheological, thermal properties and drug release profile of the gels formed for topical delivery.&#x0D; Methods: Olive and soybean oil-based Span 40 and Span 40/Tween 80 oleogel formulations were prepared by solid fiber mechanism and subjected to organoleptic evaluation, FT-IR spectroscopy, thermal analysis, rheological study, kinetic modeling of gelation and drug release.&#x0D; Results: The critical gelator (Span 40) concentration was found to be lower for olive oil (12% w/v) and depend on the type of oil. Tween 80 reduced CGC of soybean oleogels only. Soybean oil-based oleogel containing 18% w/v Span 40 was found to form more flexible, less viscous and thermally less stable formulation with better release of paracetamol as evident from lower melt flow index, Tg value, lower β and higher α value compared to olive oil-based oleogel with 12% w/v Span 40 (CGC). Surfactant addition can be assumed to modify the microarchitecture of the oleogels to a great extent to produce more flexible and thermally stable gels with even better drug release profile. Span-Tween based soybean oleogel formed a gel-matrix whereas matrix in olive oil-based oleogels containing Span only became slightly flexible to release the drug in zero-order fashion on the addition of surfactant cogelator.&#x0D; Conclusion: Nature of oil exerts profound influence on the rheological, thermal and release profile of oleogels containing Span 40 as gelator and/or Tween 80 as surfactant cogelator.

Sugar-benzohydrazide based phase selective gelators for marine oil spill recovery and removal of dye from polluted water

The synthesis of 3,4,5-tri-O-benzohydrazide based N-glycosylamines were characterized using NMR (1H and 13C) and mass spectral analysis. Gelation properties of the synthesized molecules in different solvents and oils were studied and gelation was observed with minimum Critical Gelator Concentration (CGC) of 0.8% (w/v) in benzene. The free hydroxyl group of the sugar moiety, benzohydrazide and three alkyl chains present in all these compounds afford the collective driving forces for gelation. Phase-Selective Organo-Gelators (PSOGs) are molecules that can gel the oil selectively from the biphasic combination of oil and water and it is one of the good candidates for recovering oil in case of oil spill. It is observed that these gelators can be used as solid particles on a biphasic system consist of oil and water. It solidifies the oil selectively which can be taken out by means of the physical process. FT-IR and UV–Vis spectroscopy suggest that the driving forces for the gelation are hydrogen-bonding, π-π stacking and van der Waals interaction. The gels were studied using FE-SEM, DSC and rheological techniques. FE-SEM analysis shows that the formation of thin fibers and large wrinkle like aggregate structure in the gel state is due to the presence of different weak molecular interactions. The phase selection and gel-sol transition properties of these molecules confer their ability to absorb and release dyes with high efficiency.

Solvent Effects on Gelation Behavior of the Organogelator Based on L-Phenylalanine Dihydrazide Derivatives

A series of organogelators based on L-phenylalanine has been synthesized and their gelation properties in various organic solvents were investigated. The results showed that these organogelators were capable of forming stable thermal and reversible organogels in various organic solvents at low concentrations, and the critical gel concentration (CGC) of certain solvents was less than 1.0 wt%. Afterward, the corresponding enthalpies (ΔHg) were extracted by using the van ’t Hoff equation, as the gel–sol temperature (TGS) was the function of the gelator concentration. The study of gelling behaviors suggested that L-phenylalanine dihydrazide derivatives were excellent gelators in solvents, especially BOC–Phe–OdHz (compound 4). The effects of the solvent on the self-assembly of gelators were analyzed by the Kamlet–Taft model, and the gelation ability of compound 4 in a certain organic solvent was described by Hansen solubility parameters and a Teas plot. Morphological investigation proved that the L-phenylalanine dihydrazide derivatives could assemble themselves into an ordered structure such as a fiber or sheet. Fourier-transform infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonance (1H NMR) studies indicated that hydrogen bonding, π–π stacking, and van der Waals forces played important roles in the formation of a gel.

Thermo-Reversible Hybrid Gels Formed from the Combination of Isotactic Polystyrene and [Fe(II) (4-Octadecyl-1,2,4-Triazole)3(ClO4)2]n Metallo-Organic Polymer: Thermal and Viscoelastic Properties.

Nano-sized one-dimensional metallo-organic polymers, characterized by the phenomenon of spin transition, are excellent candidates for advanced technological applications such as optical sensors, storage, and information processing devices. However, the main drawback of this type of polymers is their fragile mechanical properties, which hinders its processing and handling, and makes their practical use unfeasible. To overcome this problem, in this work, hybrid thermo-reversible gels are synthesized by combination of a metallo-organic polymer and isotactic polystyrene (iPS) in cis-decaline. A detailed investigation of the thermal and viscoelastic properties of the hybrid gels, in terms of iPS and metallo-organic polymer concentration is performed by means of differential scanning calorimetry and oscillatory rheology, respectively. From the analysis of the thermal properties, three transitions have been determined upon heating: Monotectic transition of the iPS gel, melting of the iPS gel, and melting of the metal-organic polymer gel, which suggest that the gels of the two polymers are formed independently in the hybrid gel, as long as the two polymers are in concentrations above the corresponding critical gelation concentrations. Results regarding viscoelastic properties and morphology confirmed that hybrid gels consisted of an interpenetrated network of polymer gels, formed by iPS and metallo-organic poymer gels growing independently.

Fine-Tuning the Linear Release Rate of Paclitaxel-Bearing Supramolecular Filament Hydrogels through Molecular Engineering.

One key design feature in the development of any local drug delivery system is the controlled release of therapeutic agents over a certain period of time. In this context, we report the characteristic feature of a supramolecular filament hydrogel system that enables a linear and sustainable drug release over the period of several months. Through covalent linkage with a short peptide sequence, we are able to convert an anticancer drug, paclitaxel (PTX), to a class of prodrug hydrogelators with varying critical gelation concentrations. These self-assembling PTX prodrugs associate into filamentous nanostructures in aqueous conditions and consequently percolate into a supramolecular filament network in the presence of appropriate counterions. The intriguing linear drug release profile is rooted in the supramolecular nature of the self-assembling filaments which maintain a constant monomer concentration at the gelation conditions. We found that molecular engineering of the prodrug design, such as varying the number of oppositely charged amino acids or through the incorporation of hydrophobic segments, allows for the fine-tuning of the PTX linear release rate. In cell studies, these PTX prodrugs can exert effective cytotoxicity against glioblastoma cell lines and also primary brain cancer cells derived from patients and show enhanced tumor penetration in a cancer spheroid model. We believe this drug-bearing hydrogel platform offers an exciting opportunity for the local treatment of human diseases.

Stimuli Responsive, Self-Sustainable, and Self-Healable Functionalized Hydrogel with Dual Gelation, Load-Bearing, and Dye-Absorbing Properties.

The motivation for designing low-molecular-weight gelators with self-healing characteristics originates from elegant examples in biology such as vines of the genus Aristolochia whose internal secondary growth exhibits rapid self-healing in their stems. In the present work, we had explored the stimuli-responsive dual gelation characteristics for the ester-functionalized surfactant (4-(2-(hexadecyloxy)-2-oxoethyl)-4-methylmorpholin-4-ium bromide, C16EMorphBr) in aqueous medium at 7.20% (w/v) critical gel concentration and pH 7.4. The hydrogel provides an excellent platform to study dynamic phase behavior within a supramolecular network as it exhibits transformation from a fibrillar opaque hydrogel to a transparent hydrogel upon heating. Molecular interactions, arrangement within the supramolecular framework, and mechanical properties of the hydrogels were characterized using Fourier transform infrared, small-angle neutron scattering, rheological analysis, and tensile strength and cyclic loading-unloading tests. The fibrillar opaque gel has been characterized for its morphology using scanning electron microscopy, field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The self-sustained, self-healable porous fibrillar opaque xerogel was further explored for selectively absorbing anionic dyes and for its load-bearing characteristics. We conclude a perspective on designing a new-age gelator that can open entirely new avenues in environmental protection and wearable "smart" devices.

Synthesis and self-assembly of aroylhydrazone based polycatenars: A structure-property correlation

Two series of aroylhydrazone based polycatenars which differ from each other in terms of the linking groups (semi flexible ester or flexible ether linkage) were synthesized. These hexacatenars were mesogenic and also showed gelation in organic solvents at very low concentration, which is assisted by the intermolecular hydrogen bonding. Both the series of hexacatenars were prepared by varying the peripheral chain length from n-hexyloxy to n-hexadecyloxy chain. In the case of ester based series on moving from n-decyloxy to n-dodecyloxy chain, a transition from columnar rectangular phase to columnar hexagonal phase was noticed. Such behavior was not seen in the case of ether-based hexacatenars, irrespective of the chain length. Representative hexacatenars from each series exhibited gelation at low concentration, but the critical gelation concentration of ester-based hexacatenar was almost half of that observed for ether-based hexacatenar. From these studies we can understand the importance of the linking group, which constitutes very small part of the molecule, but has a significant effect on the type of the self-assembly in bulk as well as in presence of solvents. The presence of semi-flexible ester group provides a bent conformation to the molecule, while the presence of flexible ether group provides a linear shape to the molecule, as evident from the molecular modeling studies. Further the presence of the ester group enhances the extent of intermolecular hydrogen bonding with the solvent that leads to a lower critical gelation concentration in comparison to the ether-based linking group. Such H-bonded liquid crystals have potential in the preparation of liquid crystalline physical gels and related applications.

RAFT Dispersion Polymerization in Silicone Oil

A near-monodisperse monohydroxy-terminated polydimethylsiloxane (PDMS; mean degree of polymerization = 66) was esterified using a carboxylic acid-functionalized trithiocarbonate to yield a PDMS 66 precursor with a mean degree of functionality of 92 ± 5% as determined by 1 H NMR spectroscopy. This PDMS 66 precursor was then chain-extended in turn using eight different methacrylic monomers in a low-viscosity silicone oil (decamethylcyclopentasiloxane, D5). Depending on the monomer type, such syntheses proceeded via either RAFT dispersion polymerization or RAFT emulsion polymerization. In each case the target DP of the core-forming block was fixed at 200, and the copolymer concentration was 25% w/w. Transmission electron microscopy studies indicated that kinetically trapped spheres were obtained in almost all cases. The only exception was 2-(dimethylamino)ethyl methacrylate (DMA), which enabled access to spheres, worms, or vesicles. This striking difference is attributed to the relatively low glass transition temperature for this latter block. A phase diagram was constructed for a series of PDMS 66 -PDMA x nano-objects by systematically increasing the PDMA target DP from 20 to 220 and varying the copolymer concentration between 10 and 30% w/w. Higher copolymer concentrations were required to access a pure worm phase, while only spheres, vesicles, or mixed phases were accessible at lower copolymer concentrations. Gel permeation chromatography studies indicated a linear evolution of number-average molecular weight (M n ) with PDMA DP while dispersities remained below 1.40, suggesting relatively well-controlled RAFT polymerizations. Small-angle X-ray scattering (SAXS) was used to characterize selected examples of spheres, worms, and vesicles. PDMS 66 -PDMA 100-112 worms synthesized at 25-30% w/w formed free-standing gels at 20 °C. Oscillatory rheology studies performed on a 30% w/w PDMS 66 -PDMA 105 worm dispersion indicated a storage modulus (gel strength) of 1057 Pa and a critical gelation concentration (CGC) of approximately 12% w/w. Finally, PDMS 66 -PDMA x worms could also be prepared in n-dodecane, hexamethyldisiloxane, or octamethylcyclotetrasiloxane. Rotational rheometry studies indicate that such worms are efficient viscosity modifiers for these nonpolar oils.