Silsesquioxane Framework Research Articles

Transparent self-cleaning coatings repellent to ultralow surface tension liquids in extreme environments

Self-cleaning coatings have been garnering significant attention for their ability to reduce surface pollution by repelling liquids. However, creating transparent self-cleaning coatings that effectively repel ultralow surface tension liquids in harsh environments, like extremely high or low temperature environments, remains a challenge. Here, a transparent omniphobic coating (PMAPOSS-co-PFMA) is reported to achieve the repellency of droplets with surface tensions down to 15.5 mN·m−1 (n-pentane), even at temperatures up to 160 °C and down to −70 °C. The coating is engineered by grafting fluoropolymer with fluoroalkyl side chains onto the rigid polyhedral oligomeric silsesquioxane framework. The fluoroalkyl side chains tend to crystallize on the coating's surface, resulting in its low surface tension (measured at 9.39 mN·m−1). The incorporation of the robust POSS significantly enhances the coating's chemical, mechanical, and thermal stability. Moreover, with low roughness (Ra = 1 nm), the coating has a light transmittance of 90.5 %, surpassing untreated glass by 3.2 %. Heated at 80 °C, the migration of the long-fluorinated polymer chains within the PMAPOSS-co-PFMA coating enables its self-healing properties upon damage. These results provide a new perspective to develop versatile self-cleaning omniphobic coatings suitable for practical applications in extreme environments, such as asphalt transport pipes operating in high-temperature conditions.

Enhanced Water Flux of Aromatic Polyamide Membranes by Grafting Imidazolium‐Type Ionic Liquids Containing Silsesquioxane Frameworks

AbstractAn imidazolium‐type room‐temperature ionic liquid containing silsesquioxane frameworks is successfully prepared. The polar ionic liquid products are grafted onto the surface of prepared aromatic polyamide (PA) membranes to improve water flux of PA membranes. Membranes grafted with an ionic liquid exhibit a water flux of 1.89 L m−2 h−1 bar−1), 48% higher than that of pure PA membranes while the salt rejection still remains at 96%. This improvement can be attributed to the enhanced hydrophilicity of the membrane surface, as evidenced by the reduced water contact angle.

Ionic Liquids Containing Silsesquioxane and Cyclic Siloxane Frameworks.

This paper describes the author's recent work on the preparation and properties of thermally stable ionic liquids (ILs) containing siloxane frameworks. Quaternary ammonium and imidazolium salt-type ILs containing random oligosilsesquioxane frameworks were successfully prepared via the hydrolytic condensation of the corresponding organotrialkoxysilanes by using an aqueous superacid bis(trifluoromethanesulfonyl)imide (HNTf2 ) solution as a catalyst and solvent. Imidazolium salt-type ILs containing polyhedral oligomeric silsesquioxane (POSS) frameworks were also prepared through a reaction similar to that described above by using a water/methanol mixed solution of HNTf2 . In addition, amorphous POSSs with two types of ionic groups randomly distributed in the side chain were prepared. These POSSs were ILs exhibiting fluidity at relatively low temperatures. Furthermore, imidazolium and ammonium salt-type ILs containing cyclic oligosiloxane frameworks were prepared through a reaction similar to that of the corresponding organodialkoxysilanes. The thermal decomposition temperatures of the above ILs containing siloxane frameworks were higher than those of general ILs.

Defect Engineering of Mesoporous Silica Nanoparticles for Biomedical Applications

ConspectusThe goddess Venus has been known for her armless beauty. Such a unique artistic effect teaches us that the imperfection in one aspect may result in a great aesthetics in another aspect. The existence of structural defects in nanomaterials (substitutional impurities and vacancies) endows them with diverse and fascinating physicochemical properties, such as optical properties and redox reaction capabilities. Therefore, defect engineering of controllably regulating the types and concentrations of defects in nanoparticles has been paid great attention in nanosynthetic chemistry for tailoring the performances of nanomaterials for diversified practical applications, such as biomedical applications.Mesoporous silica nanoparticles (MSNs) have been extensively applied as nanocarriers in biomedicine, due to their well-defined pore structure and particle morphology, extraordinarily large specific surface area and pore volume, tunable pore size, and framework composition. These nanoparticles have been considered as promising candidates for application in multiple therapeutic or diagnostic applications, by acting as drug carriers or supports for functional materials. The synthesis of MSN is usually based on sol–gel chemistry according to a bottom-up approach in a hydrothermal environment, where the silica precursor tetraethoxysilane molecules condense with each other and −Si–O–Si– bonds form consequently, under the assistance of surfactants as structural-directing agents, finally resulting in the formation of a mesoporous nanostructure. Accompanying the pore structure evolution, which has been being the major focus in the MSNs synthesis and application in the past decades, alternatively, the composition of MSN framework can also be elaborately engineered for the material functionalization and the application broadenings of MSNs, facilely by properly regulating the experimental conditions and reactants. Especially, the defect engineering of MSNs has been extensively explored very recently for broadening biomedical applications of these nanocarriers.In the last several years, our laboratory has developed three general strategies to engineer various functional chemical constituents in the MSN framework as structural defects, conferring the nanocarriers with multiple additional functions: (1) doping metal element M (M = Fe, Cu, Mn, Mg, Ca) in silica to form a −Si–O–M– metal silicate hybrid framework; (2) hybridizing organic group R (R = thioether, ethane, phenylene) in silica to fabricate a −Si–R–Si– molecularly organic–inorganic hybrid framework; (3) creating oxygen vacancies in silica by forming an oxygen-deficient framework abundant with −Si–Si– bonds. These material-engineering approaches have led to the generation of numbers of structural defects in the pristine silsesquioxane framework of MSNs, making these “defective nanoparticles” capable of presenting various unique physicochemical properties benefiting biomedical applications, such as triggered biodegradability for controlled drug release; catalytic performance for triggering in vivo chemical reactions generating therapeutic effects; paramagnetism for enabling magnetic resonance imaging; luminescent property for cell imaging, etc. In this Account, we will provide a concise and concentrated summary on the advances in the preparation of defective MSNs mainly in our laboratory, as well as the therapeutic and diagnostic applications of these versatile nanosystems, hoping to provide more inspirations to future nanomedicine design.

FA-BSA gated redox-triggered hollow mesoporous silica hybrid nanocapsule delivery system

In order to improve the degradation rate of silica framework and the targeted release ability of tumor drugs, this paper used a one-pot synthesis method to synthesize a redox with a silsesquioxane framework disulfide bridge and a particle size of about 150 nm. The triggered biodegradable organic-inorganic hybrid nanocapsule is a new and unique hollow mesoporous nanocapsule that is sequentially coupled with bovine serum albumin (BSA) and folic acid (FA) for the targeted release of adriamycin. As a “control gate”, BSA can prevent the premature release of drugs until the BSA coating “opens the door” in response to Glutathione(GSH) to achieve drug release. FA specifically recognizes the folate receptor on the tumor surface to achieve tumor targeting. Under acidic PH and GSH, it can achieve accelerated and complete release of drugs, and effectively consume intracellular GSH, help break the redox barrier in hypoxic cells, cause oxidative stress, and effectively inhibit tumor growth.

Surfactant-free synthesis of monodispersed organosilica particles with pure sulfide-bridged silsesquioxane framework chemistry via extension of Stöber method

Sulfide bond incorporated organosilica particles have been broadly applied to versatile biomedical applications, wherein the uniformity of particles and the sulfur content significantly dictate the ultimate performance. Unfortunately, due to the difficulty in controlling the chemical behavior of organosilica precursors in a sol–gel process, challenges still exist in developing a facile and green synthetic approach to fabricate organosilica particles with good dispersity and high sulfur content. In the present work, by extending the classic Stöber method, a surfactant-free synthesis of monodispersed organosilica particles with pure sulfide-bridged silsesquioxane framework chemistry is reported for the first time. By simply tailoring the ethanol-to-water ratio and amount of catalyst, the size of disulfide-bridged organosilica particles can be tuned from ~0.50 to ~1.20 µm. Moreover, this approach can be employed to prepare tetra-sulfide bridged silica nanoparticles with an extremely high sulfur content of 30.7 wt% and negligible cytotoxicity. Notably, taking advantage of this extended Stöber method, both hydrophilic (methylene blue) and hydrophobic (curcumin) molecules can be in-situ encapsulated into tetra-sulfide bridged silica nanoparticles, whose glutathione-triggered biodegradability is also demonstrated. Collectively, the innovative synthetic approach and organosilica particles developed in this work are expected to open up new opportunities in hybrid materials fabrication and bio-applications.

Novel biodegradable low-κ dielectric nanomaterials from natural polyphenols.

Biodegradable natural polymers and macromolecules for transient electronics have great potential to reduce the environmental footprint and provide opportunities to create emerging and environmentally sustainable technologies. Creating complex electronic devices from biodegradable materials requires exploring their chemical design pathways to use them as substrates, dielectric insulators, conductors, and semiconductors. While most research exploration has been conducted using natural polymers as substrates for electronic devices, a very few natural polymers have been explored as dielectric insulators, but they possess high dielectric constants. Herein, for the first time, we have demonstrated a natural polyphenol-based nanomaterial, derived from tannic acid as a low-κ dielectric material by introducing a highly nanoporous framework with a silsesquioxane core structure. Utilizing natural tannic acid, porous “raspberry-like” nanoparticles (TA-NPs) are prepared by a sol–gel polymerization method, starting from reactive silane unit-functionalized tannic acid. Particle composition, thermal stability, porosity distribution, and morphology are analyzed, confirming the mesoporous nature of the nanoparticles with an average pore diameter ranging from 19 to 23 nm, pore volume of 0.032 cm3 g−1 and thermal stability up to 350 °C. The dielectric properties of the TA-NPs, silane functionalized tannic acid precursor, and tannic acid are evaluated and compared by fabricating thin film capacitors under ambient conditions. The dielectric constants (κ) are found to be 2.98, 2.84, and 2.69 (±0.02) for tannic acid, tannic acid-silane, and TA-NPs, respectively. The unique chemical design approach developed in this work provides us with a path to create low-κ biodegradable nanomaterials from natural polyphenols by weakening their polarizability and introducing high mesoporosity into the structure.

Monolithic Spiropyran-Based Porous Polysilsesquioxanes with Stimulus-Responsive Properties.

Dynamic materials comprising spiropyrans have emerged as one of the most interesting and promising class of stimulus-responsive materials. Spiropyrans are often embedded in polymer matrices; their covalent attachment into porous monolithic silsesquioxane frameworks, however, is virtually unexplored. We demonstrate that a silylated spiropyran derivative can be covalently incorporated into ultralight silsesquioxane-based bulk materials by a two-step co-condensation sol–gel approach without restricting its conformational freedom and thus its stimulus-responsive properties. UV–vis measurements prove the conversion of the colorless closed-ring form of the spiropyran molecule into its highly colored purple isomer or the yellow colored protonated structure thereof. The transformation can be triggered simply by irradiation of the spiropyran-containing silsesquioxane monolith with UV or visible light or by the pH value of the chemical environment. A strong dependence of the surface polarity and water wettability on the prevalent isomer was observed. The contact angle of a water droplet on the monolithic surface can be altered from 146 to 100° by irradiation of the monolith with UV light for 3 min. Additionally, the prepared materials possess high specific surface areas, low bulk densities, and porosities of up to 84%.

Corrosion protective mechanism of smart graphene-based self-healing coating on carbon steel

Graphene sheets containing porous polyhedral oligomeric silsesquioxane (POSS) framework were synthesized as nanocontainer for self-healing organic coating. The corrosion inhibitor of benzotriazole (BTA) was loaded into the porous graphene sheets and then imbedded into epoxy coating to form composite coating. Results showed that the composite coating exhibited excellent self-healing capacity due to the spontaneous release from graphene-based nanocontainer. Through analysis, the effective protective effect of coating contained two aspects. First, the BTA could be released from the nanocontainer to form an adsorption layer on metal surface. Second, the physical barrier of graphene could greatly suppress the permeation of corrosion medium.

Gradient Redox-Responsive and Two-Stage Rocket-Mimetic Drug Delivery System for Improved Tumor Accumulation and Safe Chemotherapy.

Recent drug delivery nanosystems for cancer treatment still suffer from the poor tumor accumulation and low therapeutic efficacy due to the complex in vivo biological barriers. To resolve these problems, in this work, a novel gradient redox-responsive and two-stage rocket-mimetic drug nanocarrier is designed and constructed for improved tumor accumulation and safe chemotherapy. The nanocarrier is constructed on the basis of the disulfide-doped organosilica-micellar hybrid nanoparticles and the following dual-functional modification with disulfide-bonded polyethylene glycol (PEG) and amido-bonded polyethylenimine (PEI). First, prolonged circulation duration in the bloodstream is guaranteed due to the shielding of the outer PEG chains. Once the nanocarrier accumulates at the tumoral extracellular microenvironment with low glutathione (GSH) concentrations, the first-stage redox-responsive behavior with the separation of PEG and the exposure of PEI is triggered, leading to the improved tumor accumulation and cellular internalization. Furthermore, with their endocytosis by tumor cells, a high concentration of GSH induces the second-stage redox-responsiveness with the degradation of silsesquioxane framework and the release of the encapsulated drugs. As a result, the rocket-mimetic drug carrier displays longer circulation duration in the bloodstream, higher tumor accumulation capability, and improved antitumor efficacy (which is 2.5 times higher than that with inseparable PEG). It is envisioned that the rocket-mimetic strategy can provide new solutions for improving tumor accumulation and safety of nanocarriers in further cancer chemotherapy.

Highly thermally stable mesoporous Poly(cyanate ester) featuring double-decker–shaped polyhedral silsesquioxane framework

In this study we prepared cyanate ester–functionalized double-decker silsesquioxane (DDSQ) nanoparticles through a sequence of hydrosilylation of nadic anhydride (ND) with DDSQ and then treat with 4-aminophenol to provide DDSQ-ND-OH, and reaction with cyanogen bromide (BrCN) to form DDSQ-ND-OCN (a bis-phenyl cyanate ester DDSQ). After thermal curing of DDSQ-ND-OCN, we obtained mesoporous poly(cyanate ester) (PCE)/DDSQ frameworks that displayed high thermal stabilities and char yields since the inorganic DDSQ nanoparticles were dispersed in the PCE matrix homogeneously, as revealed using electron microscopy. Thermal polymerization at 210 °C provided a PCE/DDSQ framework having a thermal decomposition temperature (516 °C) and char yield (70 wt%); these values increased to 600 °C and 81 wt%, respectively, after thermal treatment at 420 °C. More interestingly, these mesoporous PCE/DDSQ frameworks displayed electrochemical properties better than those of other non-carbonized materials.

Facile synthesis of mesoporous organosilica nanobowls with bridged silsesquioxane framework by one-pot growth and dissolution mechanism

Mesoporous organosilica materials with organo-bridged silsesquioxane and novel structures have attracted great attention due to combined or enhanced properties. Here, we achieved facile synthesis of uniform well-defined mesoporous organosilica nanobowls with ethane- or ethane&thioether-bridged silsesquioxane framework by one-pot reaction. The possible formation mechanism may be attributed to be a dynamic growth, dissolution and reassembly process, including a uniform coating of ethane-bridged organosilica on the surface of mesoporous silica nanoparticles (MSNs) or mesoporous organosilica nanoparticles (MONs), gradual dissolution of MSNs or MONs core for the collapse of hollow spheres, and regrowth and reassembly of a small portion of the dissolved species. The framework stability of MSNs can be regulated by adjusting the amount of introduction of thioether-bridged silsesquioxane in the framework from 0 to 100%, which determines the structures of finally obtained products (nanobowls or rough nanoparticle (NPs)). The interesting results shed light on fundamental mechanisms of growth and dissolution for design and synthesis of novel structured materials. The ethane&thioether-bridged nanobowls show good hemocompatibility and low cytotoxicity compared with ethane-bridged nanobowls and calcined MCM-41-typed MSNs. The unique nanobowl structure, worm-like mesochannels and silsesquioxane framework make it as potential candidates for nanobiomedical applications.

Disulfide‐Bridged Organosilica Frameworks: Designed, Synthesis, Redox‐Triggered Biodegradation, and Nanobiomedical Applications

AbstractOver the past few years, silica‐based nanotheranostics have demonstrated their great potential for nano/biomedical applications. However, the uncontrollable and difficult degradability of their pure silica framework and long‐time in vivo retention still cause severe and unpredictable toxicity risks. Therefore, it is highly desirable to design and synthesize materials with safer framework structures and compositions. To this aim, the introduction of disulfide bonds into the silica framework can not only maintain high stability in physiological conditions, but also achieve a stimuli‐responsive biodegradation triggered by intracellular reducing microenvironment in living cells, especially in cancer cells. Once nanotheranostics with disulfide (i.e., thioether)‐bridged silsesquioxane framework are taken up by tumor cells via passive or active targeting, the disulfide bonds in the hybrid silica matrix can be cleaved by a high concentration of intracellular glutathione, enabling redox‐triggered biodegradation of the nanosystems for both concomitant release of the loaded therapeutic cargo and in vivo clearance. It is envisioned that such hybrid materials comprised of disulfide‐bridged silsesquioxane frameworks can become promising responsive and biodegradable nanotheranostics. This review summarizes the recent advances in the synthesis of hybrid organosilicas with disulfide‐bridged silsesquioxane frameworks, and discuss their redox‐triggered biodegradation behaviors combined with their biocompatibility and nanobiomedical applications.

Silsesquioxane‐Based Hexaphenylsilole‐Linked Hybrid Porous Polymer as an Effective Fluorescent Chemosensor for Metal Ions

AbstractSilsesquioxane‐based hexaphenylsilole‐linked hybrid porous polymers (SHHPP‐1, 2, and 3), prepared from one‐step Friedel‐Crafts reaction of octavinylsilsesquioxane (OVS) and 1, 1, 2, 3, 4, 5‐hexaphenylsilole (HPS), have been investigated as potential sensors for heavy metal ions. The results of FTIR, solid state CP/MAS NMR (13C and 29Si) and elemental analysis indicate that HPS unit has been successfully linked to the silsesquioxane framework. These hybrid porous polymers possess high surface areas and bimodal pore structures, and SHHPP‐2 possesses a maximum surface area of 1144 m2•g−1 and pore volume of 0.94 cm3•g−1. We have explored the application of these polymers as fluorescent chemosensors. Remarkably, this sensing system exhibits excellent sensitivity toward Fe3+, Ru3 and Cu2+, and a detection limit as low as 10−7 M is achieved, especially for Fe3+ with observed KSV =53695 M−1.

Discrimination and highly selective adsorption of phosphoproteins and glycoproteins with arginine-functionalized polyhedral oligomeric silsesquioxane frameworks

The crosstalk between phosphoproteins and glycoproteins causes many difficulties in their selective isolation/enrichment from biological samples. This issue is of high significance in proteomics study, but thus far, it has not received proper attention. Herein, an arginine-functionalized polyhedral oligomeric silsesquioxane (POSS) framework, PP-x-Arg (x = 0, 1, 2, … denotes the amount of salt in preparation), was developed by combining salt-templated thermal polymerization of POSS and pyromellitic dianhydride (PMDA) with post-modification using arginine. PP-x-Arg possesses a porous nanostructure and abundant functional groups, namely, guanidine and zwitterionic groups, enabling the selective adsorption of phosphoproteins or glycoproteins via specific phosphate-guanidine affinity or hydrophilic interaction between PP-x-Arg and glycoproteins, respectively. In particular, the adsorption selectivity exhibited by PP-x-Arg can be easily regulated by adjusting the pH values of the adsorption medium. The PP-x-Arg framework was further employed for the discrimination and isolation of phosphoproteins and glycoproteins from biological samples.

A Rapid One-Pot Synthesis of Novel High-Purity Methacrylic Phosphonic Acid (PA)-Based Polyhedral Oligomeric Silsesquioxane (POSS) Frameworks via Thiol-Ene Click Reaction.

Herein, we demonstrate a facile methodology to synthesis a novel methacrylic phosphonic acid (PA)-functionalized polyhedral oligomeric silsesquioxanes (POSSs) via thiol-ene click reaction using octamercapto thiol-POSS and ethylene glycol methacrylate phosphate (EGMP) monomer. The presence of phosphonic acid moieties and POSS-cage structure in POSS-S-PA was confirmed by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (1H, 29Si and 31P-NMR) analyses. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrum of POSS-S-PA acquired in a dithranol matrix, which has specifically designed for intractable polymeric materials. The observed characterization results signposted that novel organo-inorganic hybrid POSS-S-PA would be an efficacious material for fuel cells as a proton exchange membrane and high-temperature applications due to its thermal stability of 380 °C.

One-pot synthesis of redox-triggered biodegradable hybrid nanocapsules with a disulfide-bridged silsesquioxane framework for promising drug delivery.

Biodegradability is very critical for biomaterials to be nanocarriers. Ideal nanocarriers should be stable enough to execute their functions, but then can be efficiently got rid of, by either biodegradation or excretion. In this work, we report the design and one-pot fabrication of a series of uniform organic-inorganic hybrid nanocapsules with a disulfide-bridged silsesquioxane framework and a particle size smaller than 100 nm for redox-triggered biodegradation. The optimal synthesis conditions were explored for balancing the nanostructure, sulfur (S) content and aggregation degree. Fluorescent molecules were also integrated into the disulfide-bridged silsesquioxane framework by a co-condensation strategy for fluorescence tracking. Dithiothreitol (DTT) as a strong model reducing agent triggered the breakdown of hybrid nanocapsules without and with PEG modification from intact nanospheres to small fragments, while intracellular glutathione (GSH) had a slightly lower capacity of biodegrading these nanocapsules. The constructed delivery system obviously inhibited the growth of A549 cancer cells due to efficient cellular uptake by an endocytosis pathway and the subsequent pH and GSH-triggered drug release. The possibility of regulating the framework and surface functionalization of hybrid nanocapsules opens new opportunities for the development of silica-based degradable hybrid nanocarriers for promising drug delivery.

Development of Space-Qualified Photocurable-Silsesquioxane-Coated Polyimide Films

Silsesquioxane () has been researched as a potential atomic-oxygen protective-coating material for spacecraft applications. To this end, the present study focuses on the development of photocurable silsesquioxane ( series, manufactured by Toagosei Co., Ltd.) coating on polyimide base films. Photocurable silsesquioxanes “ series” are a new type of organic–inorganic hybrid materials that feature photoinitiated polymerizable groups (organic units) introduced into silsesquioxane frameworks (inorganic units) as multifunctional groups at an intramolecular level. This coating has the following excellent properties for use as a protective coating for space materials: 1) high atomic-oxygen tolerance, 2) high adhesion to substrate material (polyimide), 3) high transparency, 4) low outgassing and low recondensability, and 5) ease of handling. In a previous research, fundamental space-application data for two types of coatings have been presented. In this study, two types of space-qualified polyimide films have been selected, both of which were thick and aluminized on the rear. Roll-to-roll wet-coating technology has been adopted for this product with a width of 1 m. The -coated films thus obtained were evaluated for their resistance to space environmental factors, such as atomic oxygen, electron beam, and ultraviolet irradiations; thermal cycling; and high-temperature-vacuum conditions. The acquired outgassing properties complied with the American Society for Testing and Materials E 595 standard. Volume-resistivity data were also acquired. The results indicate excellent space environmental tolerance in the prepared coatings. Thus, the present study established a facile roll-to-roll wet-coating process for developing coating on two types of polyimide base films.

Tunable Gravimetric and Volumetric Hydrogen Storage Capacities in Polyhedral Oligomeric Silsesquioxane Frameworks.

We study the hydrogen adsorption in porous frameworks composed of silsesquioxane cages linked via boron substituted aromatic structures by first-principles modeling. Such polyhedral oligomeric silsesquioxane (POSS) frameworks can be further modified by decorating them with metal atoms binding to the ring structures of the linkers. We have considered Sc- and Ti-doped frameworks which bind H2 via so-called Kubas interaction between hydrogen molecules and transition metal atoms. It will be demonstrated that the maximum H2 gravimetric capacity can be improved to more than 7.5 wt % by using longer linkers with more ring structures. However, the maximum H2 volumetric capacity can be tuned to more than 70 g/L by varying the size of silsesquioxane cages. We are optimistic that by varying the building blocks, POSS frameworks can be modified to meet the targets for the gravimetric and volumetric capacities set by the U.S. Department of Energy.

Cyclopentadienyl–Silsesquioxane Titanium Catalysts: Factors Affecting Their Formation and Activity in Olefin Epoxidation with Aqueous Hydrogen Peroxide

The reaction of titanium chlorosilyl‐substituted cyclopentadienyl (Cp) complexes, Ti(η5‐C5H3R′SiMe2Cl)Cl3 (R′ = H, 1b; SiMe3, 1c), with 1 equiv. of various silsesquioxane trisilanols, R7Si7O9(OH)3 (R = iBu, 2a; Ph, 2b), affords either corner‐capped Cp derivatives, Ti(η5‐C5H3R′SiMe2Cl)(R7Si7O12‐κ3O3) (R′ = H, R = iBu, 5a, Ph, 5b; R′ = SiMe3, R = iBu, 7a, Ph, 7b), or cyclopentadienyl–silsesquioxane complexes, Ti(η5‐C5H4SiMe2OR7Si7O11‐κ2O2)Cl (R′ = H, R = iBu, 6a, Ph, 6b; R′ = SiMe3, R = iBu, 8a, Ph, 8b), depending on the reaction conditions. In any case, upon heating, kinetic products 5 and 7 are transformed into the corresponding thermodynamic products 6 and 8, respectively. The electron‐donating ability of the Cp ring is a relevant controlling parameter: a strong π‐donor character facilitates the isomerization process. In addition, the nature of the silicon substituents in the silsesquioxane framework, the type of solvent, and the reaction temperature are also factors that significantly affect this process. Cyclopentadienyl–silsesquioxane complexes 6b and 8b are efficient and selective catalysts for epoxidation with aqueous hydrogen peroxide under mild conditions. Such a catalytic efficiency is attributed to the hydrophobic environment generated about the titanium atom by the Cp ring incorporated into the cyclopentadienyl–silsesquioxane ligand.