Inorganic Domains Research Articles

The role of TEOS‐TIP within a pentablock ionomer: Morphology, physical properties, and ion transport

ABSTRACTInorganic–organic nanocomposites were created using tetraethylorthosilicate (TEOS), titanium isopropoxide (TIP), and poly(t‐butylstyrene‐b‐hydrogenated isoprene‐b‐sulfonated styrene‐b‐hydrogenated isoprene‐b‐t‐butylstyrene) or pentablock copolymer (PBC). A TEOS–TIP–H2O ternary phase diagram was generated to create homogenous sol solutions with designable condensation reactions that led to controllable materials. An inorganic TEOS–TIP network was synthesized using sol–gel chemistry within the organic PBC domain. All TEOS–TIP–PBC films exhibited higher water sorption than unmodified PBC ionomer that was attributed to a change in morphology. Proton conductivity increased up to 80% due to TEOS–TIP within the nanocomposite film. This can be attributed to ion domain redistribution and partial charge transfer from the titanate's inorganic domains to sulfonate groups that promote acid dissociation. PBC had a microphase‐separated morphology that changed with increasing TIP concentration, which was observed from atomic force microscopy and small‐angle X‐ray scattering results. Finally, thermal gravimetric analysis revealed a decrease in degradation temperature, and dynamic mechanical analysis results demonstrated reduced polymer chain mobility caused by inorganic–organic interactions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 575–586

Hybrid organic-inorganic 6FDA-6pFDA and multi-block 6FDA-DABA polyimide SiO2–TiO2 nanocomposites: Synthesis, FFV, FTIR, swelling, stability, and X-ray scattering

A series of hybrid polyimide-SiO2–TiO2 nanocomposites were fabricated from functionalized multi-block polyimides, tetraethyl orthosilicate (TEOS), and titanium isopropoxide (TIP). Polyimides were solution imidized utilizing 4,4′-hexafluoroisopropylidene diphthalic anhydride (6FDA), and stoichiometric amounts of 4,4′-hexafluoroisopropylidene diamine (6FpDA) and 3,5-diaminobenzoic acid (DABA). Organic and inorganic phase compatibility and interfacial interactions were dependent upon metal alkoxide type and polyimide carboxylic acid functional group concentration (COOH). The glass transition temperature (Tg) of [6F-DABA-25] composites increased 25 °C from 334 °C to 359 °C as measured with dynamic mechanical analysis (DMA). Polyimide swelling experiments using THF demonstrated that TiO2 created interpenetrating networks within the hybrid nanocomposite preventing dissolution, but pure SiO2 systems readily dissolved in the solvent. The mean TiO2 domain size within these composites was 102 nm, which was 10 times smaller than SiO2 (1194 nm). WAXS revealed a significant increase in hybrid composite domain spacing from 9.63 Å to 26.5 Å. This led to a reduction in the polyimde's effective density within the composites from 1.45 g/cm3 to 1.35 g/cm3, which was attributed to increasing interchain distance and decreasing chain packing density. These results are attributed to enhanced interactions between functionalized polymer chains and inorganic domains containing TiO2 and SiO2–TiO2 versus SiO2.

Facet to Facet Linking of Shape Anisotropic Inorganic Nanocrystals with Site Specific and Stoichiometric Control.

Nonclassical growth mechanisms such as self-assembly and oriented attachment are effective ways to build complex nanostructures from simpler ones. In the latter case, the nanoparticle components are electronically coupled; however, control over the attachment between nanoparticles is highly challenging and generally requires a delicate balance between dipole-, ligand-, and solvent-based interactions. To this end, we perform incomplete cation exchange with Ag+ (Cu+) on CdSe-seeded CdS nanorods and tetrapods to exclusively convert their tips into small Ag2S (Cu2S) domains. Selective removal of the ligands from these inorganic domains results in spontaneous, site-specific bridging of the nanoparticles. Using this method, we demonstrate the fabrication of polymer-like linear and branched nanoparticles with enhanced electrical properties, as well as the stoichiometric formation of nanoparticle homo- and heterodimers and tetramers. We show that linked structures can then be completely cation exchanged with Pb2+ to generate PbSe/PbS-based nanostructured photodetector media with enhanced properties.

Synthesis of SiO2/epoxy–benzoxazine ternary copolymer via sol–gel method: Thermal and mechanical behavior

Trialkoxy–terminated benzoxazine monomer was synthesized using bisphenol A (BPA), 3–aminopropyltriethoxysilane (KH–550) and paraformaldehyde. Subsequently, bisphenol F epoxy resin (F51) was pretreated with 3–isocyanatopropyltriethoxysilane (IPTS) to covalently introduce trialkoxy group into the epoxy molecular. Sol–gel process was then initiated with tetraethoxysilane (TEOS) as precursor to introduce silica structure into epoxy–benzoxazine hybrid before curing reaction. The synthesized benzoxazine and epoxy resin containing trialkoxysilane group were used as silane coupling agent to connect epoxy–benzoxazine matrix as organic domain and silica units as inorganic domain. Thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) show that the organic–inorganic ternary copolymer possesses promoted thermal stability compared with the unmodified epoxy–benzoxazine matrix. The char residues of the ternary copolymer after decomposition test reveal a dense surface layer and unbroken original dimension which is in accordance with the TGA results. According to the results of the mechanical tests and DMA, the SiO2/epoxy–benzoxazine copolymer possesses improved toughness and is more capable of absorbing deformation energy under external force.

Uranium(VI) hybrid materials with [(UO2)3(µ3‐O)(µ2‐OH)3]+as the sub–building unit via uranyl–cation interactions

AbstractThe hydrothermal reaction of uranyl nitrate with 1,4‐benzenedicarboxylic acid (H2bdc) in the presence of strontium or potassium hydroxides and nitrates afford the formation of two new uranyl hybrid materials featuring extensive uranyl‐strontium or uranyl‐potassium interactions with [(UO2)3(µ3‐O)(µ2‐OH)3]+as the sub‐building unit. Sr1.5[(UO2)12(O)3(OH)13(bdc)4]⋅6H2O (1) contains one‐dimensional (1D) uranyl oxohydroxyl ribbons made of trinuclear pentagonal bipyramidal uranyl units. The ribbons are linked together via uranyl‐strontium interactions to form 2D inorganic domains which are further connected throughµ4‐bdc anions forming a 3D hybrid structure. This is the first reported uranyl‐strontium interaction in extended hybrid solid with the shortest Sr‐O−ylbond length of 2.596 (8) Å. K3[(UO2)12(O)3(OH)13(bdc)4]⋅8H2O (2) has a similar 3D hybrid structure built up through extensive K‐O−ylinteractions with the shortest K‐O−ylbond length of 2.620 (6) Å. Raman spectroscopy has confirmed the presence of oxo‐bridging (U−O−U) vibrations. Thermal stabilities and photoluminescent properties are reported.

Liquid–Liquid Phase Separation in Mixed Organic/Inorganic Single Aqueous Aerosol Droplets

Direct measurements of the phase separation relative humidity (RH) and morphology of aerosol particles consisting of liquid organic and aqueous inorganic domains are presented. Single droplets of mixed phase composition are captured in a gradient force optical trap, and the evolving size, refractive index (RI), and morphology are characterized by cavity-enhanced Raman spectroscopy. Starting at a RH above the phase separation RH, the trapped particle is dried to lower RH and the transition to a phase-separated structure is inferred from distinct changes in the spectroscopic fingerprint. In particular, the phase separation RHs of droplets composed of aqueous solutions of polyethylene glycol (PEG-400)/ammonium sulfate and a mixture of C6-diacids/ammonium sulfate are probed, inferring the RH from the RI of the droplet immediately prior to phase separation. The observed phase separation RHs occur at RH marginally higher (at most 4%) than reported in previous measurements made from studies of particles deposited on hydrophobic surfaces by brightfield imaging. Clear evidence for the formation of phase-separated droplets of core-shell morphology is observed, although partially engulfed structures can also be inferred to form. Transitions between the different spectroscopic signatures of phase separation suggest that fluctuations in morphology can occur. For droplets that are repeatedly cycled through the phase separation RH, the water activity at phase separation is found to be remarkably reproducible (within ±0.0013) and is the same for the 1-phase to 2-phase transition and the 2-phase to 1-phase transition. By contrast, larger variation between the water activities at phase separation is observed for different droplets (typically ±0.02).

Modification of polycaprolactone-styrene-vinyl trimethoxysilane terpolymer with sunflower oil for coating purposes

Polycaprolactone-styrene-vinyl trimethoxysilane terpolymer was prepared and then modified with sunflower oil partial glyceride (SFOPG) via a sol–gel method for use as a binder in coating applications. Therefore, a vinyl-functionalized polyester-based macromonomer (HPCL) was prepared via ring-opening polymerization of ɛ-caprolactone (CL) using 2-hydroxyethyl methacrylate (HEMA) followed by copolymerization with styrene (St) and vinyl trimethoxysilane (VTMS) to yield a terpolymer (HPCL-St-VTMS). The terpolymer was characterized by FTIR, GPC and 1H NMR. To overcome the fact that the cured film of HPCL-St-VTMS was slightly soft, SFOPG was used as a modifier and was inserted to the structure via a sol–gel reaction between the hydroxyl groups and methoxy silane moieties of the terpolymer. After this modification, the softness disappeared. Nanosize inorganic domains were observed in the SEM image. Thermal analyses of the resulting cross-linked film of SFOM-HPCL-St-VTMS were performed with DSC and TGA. SFOM-HPCL-St-VTMS, which does not melt, resulted in a higher char yield and decomposition temperature at 5% weight loss compared to the unmodified HPCL-St-VTMS film. An evaluation of the film properties indicated that SFOM-HPCL-St-VTMS can be used as a coating material.

Au–Ge and Ag–Ge Heterodimers with Tunable Domain Sizes: A Supersaturation-Precipitation Route to Colloidal Hybrid Nanoparticles

Colloidal hybrid nanoparticles, which contain multiple inorganic domains that are joined together through solid–solid interfaces, exhibit particle multifunctionality as well as new and enhanced properties that can emerge from the particle–particle interactions. These hybrid nanoparticles are typically synthesized using heterogeneous seeded nucleation of one nanoparticle on the surface of another as well as using phase segregation, surface dewetting of core–shell nanoparticles, and the fusion of premade nanoparticles. However, to expand the materials diversity and the potential range of applications of such systems, alternative routes to heterogeneous seeded nucleation are needed. Here, we show that solution–liquid–solid and related supersaturation-precipitation strategies, traditionally used in the synthesis of 1D structures such as nanowires and nanorods, can also be applied to the synthesis of colloidal hybrid nanoparticles. Specifically, we show that colloidal Au and Ag nanoparticles can serve as seeds...

Hybrid organic–inorganic UV-cured films containing liquid-crystalline units

Hybrid organic–inorganic films have been prepared through a dual-cure process, involving photopolymerization (UV-curing) of a methacrylic resin and hydrolysis/condensation of alkoxysilane groups, in the presence of three different liquid crystalline oligomers bearing acrylic reactive groups and synthesized on purpose. These UV-curable mixtures have been coated on glass substrates, exposed to UV radiation in inert (nitrogen) atmosphere, then thermally treated in order to promote the occurrence of the sol–gel reaction and finally peeled off from the substrate. The morphology of the obtained films has been investigated by means of scanning electron microscopy, environmental scanning electron microscopy and atomic force microscopy measurements. Significant silica enrichment on the “gas side” of the films (i.e. the side exposed to the UV-radiation) has been found, as well as the occurrence of the formation of interesting silica conical shapes on the same side with respect to the glass counterpart. Because of the constraints exerted by the inorganic domains on the mobility of the polymer chains, the Tg values of the obtained networks have been found to increase in the presence of the silica phases, which also might have contributed to the occurrence of segregation phenomena of the liquid crystalline phases.

A Versatile Thiol‐ene/Sol–Gel Two‐Stage Curing Process Based on a Hyperbranched Polyester with Different Degrees of 10‐Undecenoyl Modification

Hybrid thiol‐ene system based on a hyperbranched polyester with different degrees of 10‐undecenoyl modification are prepared via a dual UV‐thermal process. The pristine thiol‐ene formulation shows a high reactivity towards UV curing and the addition of the inorganic precursor to the photocurable formulation does not affect the UV‐curing process. The crosslinked systems show an increase of Tg by increasing the vinyl functionality content in the HBP and a Tg increase is also evidenced in the hybrid system as a function of inorganic precursor content. Morphological investigations show that the inorganic domains generated in situ are homogeneously distributed throughout the polymeric matrix. By varying the 10‐undecenoyl modification in the terminal groups of the HBP, the size of the inorganic domains is tunable and it is possible to decrease the dimension of the silica domains by using the HBP with a higher modification degree.

Polymer/organosilica nanocomposites based on polyimide with benzimidazole linkages and reactive organoclay containing isoleucine amino acid: Synthesis, characterization and morphology properties

Polyimide–silica nanocomposites are attractive hybrid architectures that possess excellent mechanical, thermal and chemical properties. But, the dispersion of inorganic domains in the polymer matrix and the compatibility between the organic and inorganic phases are critical factors in these hybrid systems. In this investigation, a reactive organoclay was prepared via ion exchange reaction between protonated form of difunctional l-isoleucine amino acid as a swelling agent and Cloisite Na+ montmorillonite. Amine functional groups of this swelling agent formed an ionic bond with the negatively charged silicates, whereas the remaining acid functional groups were available for further interaction with polymer chains. Then organo-soluble polyimide (PI) have been successfully synthesized from the reaction of 2-(3,5-diaminophenyl)-benzimidazole and pyromellitic dianhydride in N,N-dimethylacetamide. Finally, PI/organoclay nanocomposite films enclosing 1%, 3%, 5%, 7% and 10% of synthesized organoclay were successfully prepared by an in situ polymerization reaction through thermal imidization. The synthesized hybrid materials were subsequently characterized by Fourier transform infrared spectroscopy, X-ray diffraction, electron microscopy, and thermogravimetric analysis techniques. The PI/organoclay nanocomposite films have good optical transparencies and the mechanical properties were substantially improved by the incorporation of the reactive organoclay.

Influence of Structure and Organic‐Inorganic Phase Interactions on Coating Mechanical Properties in the Ternary Goethite:Poly(HEMA):Silica System

AbstractThe trapping of nanoparticles inside a hybrid matrix is of great importance for the design of flexible devices with good mechanical properties and for the manipulation of nanoparticles whilst avoiding the use of nanopowders. In this work, transparent coloured coatings on glass were prepared by incorporating Goethite nanorods in a silica:PHEMA [poly(hydroxyethyl methacrylate)] hybrid matrix. Results show that incorporation of Goethite with a volume content higher than 27 % leads to the formation of a porous structure through a phase separation mechanism which induces a dramatic collapse of the mechanical properties. When the Goethite volume content is below 16 %, the mechanical properties of the coating are governed by the interactions between organic and inorganic domains. Goethite interacts preferentially with the silica network through the formation of hydrogen bonds and no direct interactions with PHEMA were observed. In the absence of strong covalent bonds between the silica:PHEMA hybrid and the nanoparticles, Goethite nanorods do not provide any mechanical strengthening. As a result, interpenetration between silica and PHEMA networks enables fine tuning of the final mechanical properties with the coating silica content.

In situ generation of high aspect ratio silica particles in polypropylene

Polypropylene/silica microcomposites with high aspect ratio silica fillers were in situ generated into a molten polypropylene (PP) matrix. The synthesis of the inorganic domains are based on hydrolysis-condensation reactions of both alkoxysilanes precursors, the tetraethoxysilane (TEOS) and the Dynasil® 40 (composed of TEOS and partially condensed TEOS with residual ethoxy groups) respectively. The sol–gel reactions kinetics studied at room temperature into an acid hydroalcoholic medium for several conditions of pH associated to the processing conditions were the keys factors to control the deformability of the inorganic droplets. Thanks to a shearing hot stage coupled with an optical microscope, silica needles were obtained with a Dynasil® 40 solution treated 120 min at pH = 3 in presence of 4 g of ethanol and then placed between two slices of PP in the stage. The deformation of the droplets were then observed once the material was molten and a shearing applied. On the contrary, no deformation was possible with TEOS precursors solutions. The results transposed to the microextruder process equipped at the die with a drawing line allowed to obtain a well pronounced elongated shape of the silica particles dispersed in the polypropylene matrix.

Hybrid thin films derived from UV-curable acrylate-modified waterborne polyurethane and monodispersed colloidal silica

Hybrid thin films containing nano-sized inorganic domains were synthesized from UV-curable acrylate-modified waterborne polyurethane (WPU-AC) and monodispersed colloidal silica with coupling agent. The coupling agent, 3- (trimethoxysilyl)propyl methacrylate (MSMA), was bonded onto colloidal silica first, and then mixed with WPU-AC to form a precursor solution. This precursor was spin coated, dried and UV-cured to generate the hybrid films. The silica con- tent in the hybrid thin films was varied from 0 to 30 wt%. Experimental results showed the aggregation of silica particles in the hybrid films. Thus, the silica domain in the hybrid films was varied from 30 to 50 nm by the different ratios of MSMA- silica to WPU-AC. The prepared hybrid films from the crosslinked WPU-AC/MSMA-silica showed much better thermal stability and mechanical properties than pure WPU-AC.

Organic‐Inorganic Molecular Nano‐Sensors: A Bis‐Dansylated Tweezer‐Like Fluoroionophore Integrating a Polyoxometalate Core

AbstractFunctionalization of the bis‐lacunary Keggin polyoxotungstate [γ‐SiW10O36]8– has been achieved with a two‐step synthesis, by the covalent attachment of a 3‐aminopropylsilane spacer and further linkage of the dansyl (5‐dimethylamino‐1‐naphthalenesulfonyl‐) residue. The resulting bis‐decorated molecular hybrid [{{(CH3)2N}C10H6SO2NH(CH2)3Si}2O(γ‐SiW10O36)]4– has been isolated and characterized in solution and in the solid state by FTIR, multinuclear NMR, ESI‐MS, UV/Vis, luminescence spectroscopy, dynamic light scattering (DLS), and Scanning Electron Microscopy (SEM). The inorganic polyoxometalate provides a molecular nano‐surface where the dansyl fluorophores are anchored with a tweezer‐type arrangement. The merging of the organic and inorganic domains of the bis‐dansylated complex dictates its fluorescence features, which are observed in the range 375–600 nm, its amphiphilic properties, and the multi‐site recognition/signaling of cationic analytes due to the complementary effect of the tungsten oxide polyanionic surface. Indeed, the interplay of the appended sulfonamide moieties and of the molecular metal oxide fosters an enhanced selectivity for Cu2+ and Pb2+ ion sensing, even in the presence of potentially interfering cations such as Co2+. These latter are preferentially captured by the inorganic platform. By virtue of its hybrid nature, the title fluoroionophore evolves to supramolecular architectures and extended systems in mixed organic solvent/aqueous environment, yielding spherical vesicles and macroporous thin films. Flat polymeric membranes incorporating the hybrid fluorophore can also be obtained, suggesting the generation of heterogeneous sensing devices that integrate both filtration and separation functionalities.

Preparation of high-refractive-index trimethoxybenzene novolac-titania hybrid

Recently, hybrid materials have received considerable attention owing to the fact that they particularly exhibit enhanced mechanical, thermal, and optical properties. Among these materials, optical materials, in particular, with a high refractive index have attracted considerable attention as advanced materials that can be applied to display devices, organic light-emitting diodes (OLEDs), and antireflective coatings. A sol-gel reaction was extensively used for the synthesis of inorganic moiety in order to cap on the functionalized organic structure. The possibility of developing hybrid materials with an improved refractive index using common polymers such as poly(methyl methacrylate) (PMMA) and polyimide (PI) has been investigated. It should be noted that large molecular volume fractions of an inorganic unit have an effect on the refractive index of a hybrid material. However, the morphology of the inorganic unit of a common polymer can have an adverse effect on the aggregated inorganic domain size between the inorganic sites and the organic matrixes. In order to develop a hybrid polymer with an improved refractive index, it is essential to control the inorganic domain size to less than 40 nm to avoid light scattering. A welldispersed inorganic moiety on a nanoscale, without aggregation units, is important from the viewpoint of many optical applications owing to the fact that the transparency of hybrid polymers has an impact on their advanced optical property. The possibility of controlling the aggregation size and achieving phase separation between a polymer matrix and inorganic materials, which are used to fabricate hybrid films, by a sol-gel reaction has been investigated by many researchers. Phenolic resins have been widely studied for their applications in many fields owing to the fact that they exhibit high thermal and chemical resistances and high mechanical strength and that they are inexpensive. However, the disadvantages of phenolic resins are that it is difficult to control their molecular weight, molecular structure, and reactivity. Therefore, we have been conducting studies to investigate the manner in which the solubility of phenolic resins can be improved; we have also been conducting studies to develop phenolic derivatives such as alkoxybezene, monoor multisubstituted phenol, and naphthalene derivatives. Functionalized common polymers have received considerable interest owing to the fact that they comprise improved reactive sites that serve as functional units for the attached pendent groups. In this communication, we report a simple method for synthesizing poly(phenylenemethylene):alkoxylated novolac (hybrid PPM) as an optical material. This research focused on improving the refractive index of functionalized PPM by the sol-gel reaction. An attempt was made to synthesize this hybrid phenolic resin with an improved refractive index by a simple synthetic route. Hybrid PPM comprising titania was synthesized by using a novel functionalized PPM. The synthesized PPM comprises a carboxylic acid group as the functional group.

Synthesis and Characterization of Processable Polyimide Titania Nanohybrids

A new aromatic diamine monomer {4-amino [4-(diphenylamino) phenyl] anilino} phenyl amine (DPA -4) were synthesized in high yield and purity. {4-amino [4-(diphenylamino) phenyl] anilino} phenyl amine (DPA -4) monomer were reacted with Tetra carboxylic dianhydride (BT) leading to the formation of polyamic acid, followed by the preparation of polyimide/Titania hybrid films through non-hydrolytic sol-gel method. The synthesized polyimide were considered as blank & compared with the nano-hybrids derived from polyimides/Titania blends of different TiO2content. Synthesized polyimide showed excellent solubility in aprotic solvents like DMF, DMSO, NMP, and DMAC proving best processibility in various applications. Polyimide exhibited excellent thermal stability and its glass transition temperature was 450°C & 5% weight loss is in the range of 500°C~600°C. The thermal stability of Polyimide/Titania composites decreased slightly with increase of TiO2content. Result show decrease in thermal stability of nano-hybrids caused by the decomposition of catalytic activity of Titania & incomplete imidizations of polyamic acid. The absorption band of PI-O-Ti bonds in FTIR spectra of hybrids films revealed the formation of hybrid inorganic network between polyimide and TiO2.Scanning electron microscopy results indicated that the nanometer-scaled inorganic domains were homogeneously dispersed in polyimides matrix due to the introduction of TiO2.The studies on the optical properties of hybrids films indicated the red-shift to the absorption band increased with increasing TiO2content, while all the hybrids films maintained their transparencies. This kind of hybrid materials has potential commercial application in the field of opto-electronics appliances.

Preparation of sol–gel-based nanostructured hybrid coatings; part 1: morphological and mechanical studies

Attempts have been made using sol–gel-based precursors to produce hybrid organic–inorganic clearcoats. To this end, a typical automotive acrylic/melamine clearcoat with tetramethyl ortosilicate (TEOS) and methacryoloxy propyltrimethoxysilane (MEMO) were used to obtain nanostructured silica clusters produced in situ embedded in the polymeric matrix. Microscopic techniques including scanning electron microscope (SEM), atomic force microscope (AFM), and transmission electron microscope (TEM) were utilized to investigate the morphology of coatings. The effect of each precursor on coating mechanical properties was also studied using dynamic mechanical thermal analysis (DMTA) as well as micro and nanoindentation techniques. It was found that using TEOS and MEMO (in non-hydrolyzed state), the mechanical properties of the resulting films were negatively influenced. The decreased hardness, lower Tg and cross-linking density, and reduced elastic modulus were observed with non-hydrolyzed precursors. In addition, the phase separation of organic and inorganic domains occurred in the presence of pristine sol–gel precursors. However, using hydrolyzed precursors (HTEOS and HMEMO), the mechanical properties were notably improved. While HTEOS resulted in an increase in coating Tg, and cross-linking density as well as improved elastic modulus and hardness, HMEMO caused an increase in coating hardness but lowered coating Tg and cross-linking density.

ChemInform Abstract: Hybrid Polyoxometalates: Merging Organic and Inorganic Domains for Enhanced Catalysis and Energy Applications

AbstractReview: 207 refs.

The influence of temperature and interface strength on the microstructure and performance of sol–gel silica–epoxy nanocomposites

A series of silica–epoxy nanocomposites were prepared by hydrolysis of tetraethoxysilane within the organic matrix at different processing temperatures, i.e., 25 and 60 °C. Epoxy matrices reinforced with 2.0–10.0 wt% silica were subsequently crosslinked with an aliphatic diamine hardener to give optically transparent nanocomposite films. Interphase connections between silica networks and organic matrix were established by in situ functionalization of silica with 2.0 wt% γ-aminopropyltriethoxysilane (APTS). The microstructure of silica–epoxy nanocomposites as studied by transmission electron microscopy indicated the formation of very well-matched nanocomposites with homogeneous distribution of silica at relatively higher temperatures and in the presence of APTS. Thermogravimetric and static mechanical analyses confirmed considerable increase in thermal stability, stiffness, and toughness of the modified composite materials as compared to neat epoxy polymer and unmodified silica–epoxy nanocomposites. A slight improvement in the glass transition temperatures was also recorded by differential scanning calorimetry measurements. High temperature of hydrolysis during the in situ sol–gel process not only improved reaction kinetics but also promoted mutual solubility of the two phases, and consequently enhanced the interface strength. In addition, APTS influenced the size and distribution of the inorganic domain and resulted in better performance of the modified silica–epoxy nanocomposites.