Flexible Epoxy Resins Formed by Blending with the Diblock Copolymer PEO-b-PCL and Using a Hydrogen-Bonding Benzoxazine as the Curing Agent

In this study, we enhanced the toughness of epoxy resin by blending it with the diblock copolymer poly(ethylene oxide⁻b⁻ε-caprolactone) (PEO-b-PCL) with a benzoxazine monomer (PA-OH) as the thermal curing agent. After thermal curing, Fourier transform infrared spectroscopy revealed that intermolecular hydrogen bonding existed between the OH units of the epoxy⁻benzoxazine copolymer and the C⁻O⁻C (C=O) units of the PEO (PCL) segment. Differential scanning calorimetry and dynamic mechanical analysis revealed that the glass transition temperature and storage modulus of the epoxy⁻benzoxazine matrix decreased significantly upon increasing the concentration of PEO-b-PCL. The Kwei equation predicted a positive value of q, consistent with intermolecular hydrogen bonding in this epoxy⁻benzoxazine/PEO-b-PCL blend system. Scanning electron microscopy revealed a wormlike structure with a high aspect ratio for PEO-b-PCL as the dispersed phase in the epoxy⁻benzoxazine matrix; this structure was responsible for the improved toughness.

Synthesis of well-defined PCL-b-PnBA-b-PMMA ABC-type triblock copolymers: toward the construction of nanostructures in epoxy thermosets

A novel PCL-b-PnBA-b-PMMA was designed and applied to construct ordered nanostructures within epoxy thermosets.

Using benzoxazine chemistry and bio-based triblock copolymer to prepare functional porous polypeptide capable of efficient dye adsorption

A functional porous PTyr with phenolic OH and amide units through the selective cancelation of the PCL-b-PEO block segment from PCL-b-PEO-b-PTyrBZ triblock copolymer and used for dye adsorption.

Polybenzoxazine/Polyhedral Oligomeric Silsesquioxane (POSS) Nanocomposites

The organic/inorganic hybrid materials from polyhedral oligomeric silsesquioxane (POSS, inorganic nanoparticles) and polybenzoxazine (PBZ) have received much interesting recently due to their excellent thermal and mechanical properties, flame retardance, low dielectric constant, well-defined inorganic framework at nanosized scale level, and higher performance relative to those of non-hybrid PBZs. This review describes the synthesis, dielectric constants, and thermal, rheological, and mechanical properties of covalently bonded mono- and multifunctionalized benzoxazine POSS hybrids, other functionalized benzoxazine POSS derivatives, and non-covalently (hydrogen) bonded benzoxazine POSS composites.

Flexible Epoxy Resin Formed Upon Blending with a Triblock Copolymer through Reaction-Induced Microphase Separation

In this study, we used diglycidyl ether bisphenol A (DGEBA) as a matrix, the ABA block copolymer poly(ethylene oxide–b–propylene oxide–b–ethylene oxide) (Pluronic F127) as an additive, and diphenyl diaminosulfone (DDS) as a curing agent to prepare flexible epoxy resins through reaction-induced microphase separation (RIMPS). Fourier transform infrared spectroscopy confirmed the existence of hydrogen bonding between the poly(ethylene oxide) segment of F127 and the OH groups of the DGEBA resin. Small-angle X-ray scattering, atomic force microscopy, and transmission electron microscopy all revealed evidence for the microphase separation of F127 within the epoxy resin. Glass transition temperature (T_g) phenomena and mechanical properties (modulus) were determined through differential scanning calorimetry and dynamic mechanical analysis, respectively, of samples at various blend compositions. The modulus data provided evidence for the formation of wormlike micelle structures, through a RIMPS mechanism, in the flexible epoxy resin upon blending with the F127 triblock copolymer.

Hydrogen bonding strength effect on self-assembly supramolecular structures of diblock copolymer/homopolymer blends

The steric hindrance effect on the hydrogen bonding strength and self-assembly supramolecular structures of the PS-b-PVPh diblock copolymer when blended with P4VP and P2VP homopolymers was investigated.

Hybrid Mesoporous Silicas and Microporous POSS-Based Frameworks Incorporating Evaporation-Induced Self-Assembly

We fabricated a series of mesoporous silicas and mesoporous organosilicates with hierarchical porosity through evaporation-induced self-assembly using Pluronic F127 as a template in this study. We could tailor the mesophase of each mesoporous silica sample by varying the weight ratio of its two silica sources: tetraethyl orthosilicate (TEOS) and triethoxysilane hydrosilylated octavinyl polyhedral oligomeric silsesquioxane (OV-POSS-SILY). The mesophases ranged from an ordered body-centered cubic (bcc) structure (TEOS alone) to ordered face-centered cubic (fcc) structure (10 and 20 wt.% of OV-POSS-SILY) and finally to disordered spherical pores (≥30 wt.% of OV-POSS-SILY). We used small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) to study the transformations of these mesophases, while N₂ isotherm sorption curves revealed the porosities of these mesoporous silicate samples. Moreover, ²⁹Si CP/MAS solid state nuclear magnetic resonance spectroscopy allowed us to analyze the compositions of the POSS-containing silicate frameworks. Such functional mesoporous silica samples incorporating microporous POSS building units have potential applications in various systems, including optical and electronic devices.

Crystallization ability of poly(lactic acid) block segments in templating poly(ethylene oxide-b-lactic acid) diblock copolymers affects the resulting structures of mesoporous silicas

Eliminating the crystallization ability of PLLA to amorphous PLA block segment allowed us to obtain long-range-ordered mesoporous materials.

Supramolecular functionalized polybenzoxazines from azobenzene carboxylic acid/azobenzene pyridine complexes: synthesis, surface properties, and specific interactions

Supramolecular complex of azobenzene carboxylic acid/pyridine functionalized benzoxazine system featured significantly lower curing temperatures and maintain high water contact angles.

A simple method to introduce phosphoester groups into a polybenzoxazine backbone as multifunctional modifiers

Phosphoester groups were conveniently introduced into benzoxazine monomers by chemical bonding through nucleophilic reaction of a benzoxazine ring with diethyl phosphite (DEP).

Solvent-tuning of ordered mesoporous silicas prepared through evaporation-induced self-assembly templated by poly(ethylene oxide-b-ε-caprolactone)

Highly ordered mesoporous silicas having narrow pore size distributions and various morphologies merely through selection of an appropriate solvent.

Dendritic organic–inorganic hybrid polyphenol and branched benzoxazine monomers with low curing temperature

A novel dendritic organic–inorganic hybrid polyphenol (T2) based on cyclotriphosphazene was synthesized by the condensation reaction of T1 and phenol catalysed by phosphotungstic acid.

Hydrogen Bonding-Mediated Microphase Separation during the Formation of Mesoporous Novolac-Type Phenolic Resin Templated by the Triblock Copolymer, PEO-b-PPO-b-PEO

After blending the triblock copolymer, poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-b-PPO-b-PEO) with novolac-type phenolic resin, Fourier transform infrared spectroscopy revealed that the ether groups of the PEO block were stronger hydrogen bond acceptors for the OH groups of phenolic resin than were the ether groups of the PPO block. Thermal curing with hexamethylenetetramine as the curing agent resulted in the triblock copolymer being incorporated into the phenolic resin, forming a nanostructure through a mechanism involving reaction-induced microphase separation. Mild pyrolysis conditions led to the removal of the PEO-b-PPO-b-PEO triblock copolymer and formation of mesoporous phenolic resin. This approach provided a variety of composition-dependent nanostructures, including disordered wormlike, body-centered-cubic spherical and disorder micelles. The regular mesoporous novolac-type phenolic resin was formed only at a phenolic content of 40–60 wt %, the result of an intriguing balance of hydrogen bonding interactions among the phenolic resin and the PEO and PPO segments of the triblock copolymer.