Phthalide cardo chain extended imine skeletal linked maleimido end capped nanotitania reinforced novel polybenzoxazine (nTiO2/PBZ) hybrid nanocomposites

A new class of nanotitania reinforced polybenzoxazine (nTiO2/PBZ) hybrid nanocomposites was synthesized using newly designed phthalide cardo chain extended imine skeletal linked maleimido end capped polybenzoxazine (PHM-PBZ) and nTiO2 through in-situ sol-gel method. The formation of hybrid nanocomposites was confirmed by NMR and FT-IR spectra. The structurally stable nTiO2 present in the nTiO2/PBZ hybrids accounted their exceptional thermal stability and good char yield. The restricted motion of flexible polymeric chain resulted from the inclusion of nTiO2 in the PBZ system increased the glass transition temperature ( T g) to a higher percentage than that of neat PBZ system. With the successive enhancement in the incorporation of nTiO2, the synthesized nanocomposites exhibited better thermal stability, higher flame retardancy and lesser water absorption behaviour than the of neat PBZ. The sequential increments in the loading level of nTiO2 onto the PBZ matrices caused the lower value of dielectric constant than that of neat PBZ. The homogeneity and successful dispersion of the nTiO2 fillers in the PBZ matrix were ascertained from the strong fluorescent emissions observed in the wavelength range of 300–550 nm through optical studies. Scanning electron microscope and transmission electron microscopic micrographs evidenced the successful incorporation of nTiO2 as can be seen from the different morphology at the nanoscale level in the PBZ matrix. This kind of structurally designed nTiO2/PBZ nanocomposites may find multifaceted applications in the form of adhesives, encapsulants, matrices and sealants and in the fields of automobile and microelectronics applications for better performance and longevity.

Review on the Accelerated and Low-Temperature Polymerization of Benzoxazine Resins: Addition Polymerizable Sustainable Polymers

Due to their outstanding and versatile properties, polybenzoxazines have quickly occupied a great niche of applications. Developing the ability to polymerize benzoxazine resin at lower temperatures than the current capability is essential in taking advantage of these exceptional properties and remains to be most challenging subject in the field. The current review is classified into several parts to achieve this goal. In this review, fundamentals on the synthesis and evolution of structure, which led to classification of PBz in different generations, are discussed. Classifications of PBzs are defined depending on building block as well as how structure is evolved and property obtained. Progress on the utility of biobased feedstocks from various bio-/waste-mass is also discussed and compared, wherever possible. The second part of review discusses the probable polymerization mechanism proposed for the ring-opening reactions. This is complementary to the third section, where the effect of catalysts/initiators has on triggering polymerization at low temperature is discussed extensively. The role of additional functionalities in influencing the temperature of polymerization is also discussed. There has been a shift in paradigm beyond the lowering of ring-opening polymerization (ROP) temperature and other areas of interest, such as adaptation of molecular functionality with simultaneous improvement of properties.

New zinc complexes derived from "self-adaptable" acyclic diiminodipyrromethanes as potent catalysts for the reduction of curing temperature of bisphenol-A/F benzoxazines

The simple modification of the Schiff-base ligands often brings significant changes in the coordination properties of the metal-complexes, providing newer prospects for their unexplored applications. In this context, the present work utilized the “self-adaptable” acyclic diiminodipyrromethane Schiff's bases (2a and 2b) for the synthesis of their Zn-based complexes and explored their potential in the ring-opening polymerization of benzoxazines. The two zinc complexes of composition [Zn{(Ph)(CH₃)C(2,6-ⁱPr₂C₆H₃–N Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> CH–C₄H₂N)(2,6-ⁱPr₂C₆H₃–NCH–C₄H₂NH)}₂] (3) and [ZnCl₂{(Ph)(CH₃)C(Ph₃C–NHCH–C₄H₂N)₂}] (4) were synthesized in good yields, and the structures were confirmed by single crystal X-ray diffraction (XRD). Later, zinc complexes (3 & 4) were used as catalysts to reduce the curing (ring-opening polymerization) temperature of benzoxazine monomers such as Bisphenol-A (BA-a) and Bisphenol-F (BF-a) benzoxazines. Dynamic scanning calorimetry (DSC) studies revealed that the on-set curing (T_p) temperatures were reasonably decreased upto 20% for the benzoxazines. Furthermore, the thermal stabilities of the polybenzoxazines (PBzs) derived in the presence of zinc catalysts (3 and 4) were compared with PBz obtained in the absence of catalyst under similar conditions. The thermal studies reveled that there is no significant changes in the initial degradation of polymers. However, the thermal stability in terms of char yields at 800 °C improved upto 10–21% for the bisphenol-A/F benzoxazines.

The present work utilized the “self-adaptable” acyclic diiminodipyrromethane Schiff's bases (2a and 2b) for the synthesis of their Zn-based complexes and explored their potential in the ring-opening polymerization of BA-a and BF-a benzoxazines.

In(NO3)3 catalyzed curing reaction of benzoxazine

Benzoxazine is a new kind of thermoset resin with excellent properties, but it suffers from high curing temperature and low char yield in the presence of catalyst without halogen. In(NO3)3 was herein used for the first time to efficiently catalyze the curing reaction of benzoxazine and to elevate the char yield at 800°C. The reaction of benzoxazine was catalyzed by In(NO3)3 after stirring at 35°C for 300 min, and the initial curing temperature decreased to 151°C. Polybenzoxazine/In(NO3)3 showed higher thermal stability and char yield at 800°C (increased by 7.5%) compared with those of polybenzoxazine. The possible pathway of coordination bonding between In3+ and benzoxazine was proposed. In the cross-linking process, two different structures, that is, the N, O-acetal bridge structure and arylamine Mannich bridge structure formed at 35°C, both existed, which ultimately affected the thermal stability of the cured product.

Mesoporous Silica-Based Materials for Electronics-Oriented Applications

Electronics, and nanoelectronics in particular, represent one of the most promising branches of technology. The search for novel and more efficient materials seems to be natural here. Thus far, silicon-based devices have been monopolizing this domain. Indeed, it is justified since it allows for significant miniaturization of electronic elements by their densification in integrated circuits. Nevertheless, silicon has some restrictions. Since this material is applied in the bulk form, the miniaturization limit seems to be already reached. Moreover, smaller silicon-based elements (mainly processors) need much more energy and generate significantly more heat than their larger counterparts. In our opinion, the future belongs to nanostructured materials where a proper structure is obtained by means of bottom-up nanotechnology. A great example of a material utilizing nanostructuring is mesoporous silica, which, due to its outstanding properties, can find numerous applications in electronic devices. This focused review is devoted to the application of porous silica-based materials in electronics. We guide the reader through the development and most crucial findings of porous silica from its first synthesis in 1992 to the present. The article describes constant struggle of researchers to find better solutions to supercapacitors, lower the k value or redox-active hybrids while maintaining robust mechanical properties. Finally, the last section refers to ultra-modern applications of silica such as molecular artificial neural networks or super-dense magnetic memory storage.

SBA15-Fluconazole as a Protective Approach Against Mild Steel Corrosion: Synthesis, Characterization, and Computational Studies

A SBA15-Fluconazole composite (SBA15-Flu) was prepared to formulate a self-healing coating for mild steel. The composite was obtained by dispersing SBA15 in a methanolic solution containing Fluconazole (Flu). The materials were characterized by using different techniques. Electrochemical impedance spectroscopy (EIS) was used for protective behavior evaluation of the coatings on mild steel substrates in an electrolytic solution prepared from sodium chloride and ammonium sulfate. The EIS results indicate that the inhibitor trapped in the SiO2 matrix is released when it comes into contact the aggressive solution, thus protecting the metal. To understand the inhibitor release mechanism, docking studies were used to model the SBA15-Flu complex, which allowed us to further determine polar and non-polar contributions to the binding free energy. An analysis of the electron density within the quantum theory of atoms in molecules and the non-covalent interaction index frameworks were also carried out for the most favorable models of SBA15-Flu. The results indicate that the liberation rate of the Flu molecules is mainly determined by the formation of strong O-H⋅⋅⋅O, O-H⋅⋅⋅N, and O-H⋅⋅⋅F hydrogen bonds.

Dielectric Properties for Nanocomposites Comparing Commercial and Synthetic Ni- and Fe3O4-Loaded Polystyrene

Nanomaterial-loaded thermoplastics are attractive for applications in adaptive printing methods, as the physical properties of the printed materials are dependent on the nanomaterial type and degree of dispersion. This study compares the dispersion and the impact on the dielectric properties of two common nanoparticles, nickel and iron oxide, loaded into polystyrene. Comparisons between commercial and synthetically prepared samples indicate that well-passivated synthetically prepared nanomaterials are dispersed and minimize the impact on the dielectric properties of the host polymer by limiting particle-particle contacts. Commercial samples were observed to phase-segregate, leading to the loss of the low-k performance of polystyrene. The change in the real and imaginary dielectric was systematically studied in two earth abundant nanoparticles at the concentration between 0 and 13 vol % (0-50 wt %). By varying the volume percentage of fillers in the matrix, it is shown that one can increase the magnetic properties of the materials while minimizing unwanted contributions to the dielectric constant and dielectric loss. The well-dispersed nanoparticle systems were successfully modeled through the Looyenga dielectric theory, thus giving one a predictive ability for the dielectric properties. The current experimental work coupled with modeling could facilitate future material choices and guide design rules for printable polymer composite systems.

Low-Dissipation Thermosets Derived from Oligo(2,6-Dimethyl Phenylene Oxide)-Containing Benzoxazines

Poly(2,6-dimethyl phenyl oxide) (PPO) is known for its low dissipation factor. To achieve insulating materials with low dissipation factors for high-frequency communication applications, a telechelic oligomer-type benzoxazine (P-APPO) and a main-chain type benzoxazine polymer (BPA-APPO) were prepared from an amine end-capped oligo (2,6-dimethyl phenylene oxide) (APPO). The APPO was prepared from a nucleophilic substitution of a phenol-end capped oligo (2,6-dimethyl phenylene oxide) (a commercial product, SA 90) with fluoronitrobenzene, and followed by catalytic hydrogenation. After self-curing or curing with a dicyclopentadiene-phenol epoxy (HP 7200), thermosets with high-Tg and low-dissipation factor can be achieved. Furthermore, the resulting epoxy thermosets show better thermal and dielectric properties than those of epoxy thermoset cured from its precursor SA90, demonstrating it is a successful modification in simultaneously enhancing the thermal and dielectric properties.

Cardanol based benzoxazine blends and bio-silica reinforced composites: thermal and dielectric properties

In the present work, a novel cardanol based benzoxazine was synthesised by reacting three different amines (aniline (CrAb), N,N-dimethylaminopropylamine (CrDb) and caprolactam modified N,N-dimethylaminopropylamine (CrCb)) with cardanol in the presence of formaldehyde under appropriate experimental conditions.

Nair K, Surendran KP. Silver-Decorated Boron Nitride Nanosheets as an Effective Hybrid Filler in PMMA for High-Thermal-Conductivity Electronic Substrates

High-thermal-conductivity and low-dielectric-loss polymer nanocomposites have gained tremendous attention in microelectronics technology. Against this background, the present study deals with the development of a high-thermal-conductivity, low-dielectric-constant, and low-loss polymer nanocomposite based on silver nanoparticle (AgNP)-decorated boron nitride nanosheets (BNNSs) as the filler in poly(methyl methacrylate) (PMMA) matrix. The nanocomposites were prepared through a facile solution-blending process. Elemental mapping of the prepared nanocomposite indicates the uniform distribution of filler particle in PMMA matrix. An impressive high-thermal conductivity (TC) enhancement of around 363% was achieved for nanocomposite of 0.35 V _f of hybrid filler (1.48 W/m K) compared to pristine PMMA (0.32 W/m K). The addition of AgNP reduces the thermal contact resistance (R _c) by bridging individual BNNS, thereby improving thermal transport. Measured TC values were fitted with a theoretical model that showed good agreement. Dielectric measurements performed at radiofrequencies and microwave frequencies revealed that the nanocomposites show a low dielectric constant (<5), low loss (10^-2), and very low alternating current conductivity (10^-7 S/cm). The results suggest that silver-decorated BNNS is a promising hybrid filler for effective thermal management.

POSS-benzocyclobutene (POSS-BCB) resin

Organic-inorganic hybrid materials with a high thermal stability and a low dielectric constant show great potential in the microelectronics industry. In this work, polyhedral oligomeric silsesquioxane-benzocyclobutenes (POSS-BCBs) were synthesized by a hydrosilylation reaction of octavinyloctasilasesquioxane (OVPOSS) and 4-(1,1-dimethyl-1-hydro)-silyl-benzocyclobutene with H2PtCl6 as a catalyst. The ring-opening reaction of BCB on POSS-BCBs resulted in POSS-BCB resins with a highly cross-linked network structure. This resin exhibited good thermal stability (T5% is 495°C in N2), low dielectric constants (<2.1 at 20 MHz) and low water absorption.

Achieving low dielectric, surface free energy and UV shielding green nanocomposites via reinforcing bio-silica aerogel with polybenzoxazine

Silica aerogel (SA) derived from rice husk ash was functionalized using benzoxazine terminated silane (FSA) and was used as a nanoreinforcement for industrial valuable resin polybenzoxazine (PBZ) in order to achieve low dielectric, to improve the surface as hydrophobic and to enhance the UV shielding behavior of the resulting nanocomposites.

Low dielectric behavior of amine functionalized MCM-41 reinforced polyimide nanocomposites

A class of low dielectric constant polyimide (PI) composites was prepared by means of reduced polarization. Consequently, the nonpolar group of long aliphatic chain bridged diamine was synthesized and utilized to prepare PI with pyromellitic dianhydride and subsequently the porous amine-functionalized mobil composition of matter no. 41 (FMCM-41) was synthesized and reinforced into the PI matrix with a view to reduce the value of dielectric constant of PI. Various analytical techniques such as Fourier transform infrared, proton nuclear magnetic resonance, and carbon nuclear magnetic resonance were used to characterize and confirm the synthesized monomer and polymer. The porous nature of hybrid polymer nanocomposites was ascertained using transmission electron microscopic images, and the aggregations of nanoparticles were confirmed by scanning electron microscopic images. The mechanical (tensile) and dielectric behaviors of a material were ascertained by the measurement of porosity. The optimum concentration of FMCM-41-reinforced PI (7 wt% FMCM-41/PI) has the lowest value of dielectric constant of 2.21 at 1 MHz, and beyond this concentration (10 wt% FMCM-41/PI), the reverse trend was observed in the values of dielectric constant and dielectric loss, due to the agglomeration of silica nanoparticles in the PI matrix.

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.

Ternary polybenzoxazine/POSS/SWCNT hybrid nanocomposites stabilized through supramolecular interactions

In this study we linked zero-dimensional polyhedral oligomeric silsesquioxane (POSS) with one-dimensional single-walled carbon nanotubes (SWCNTs) as dual-dimensional nanohybrid complexes within polybenzoxazine matrices, stabilized through noncovalent supramolecular interactions. First, we synthesized a new bifunctionalized benzoxazine (Py-Bz-T), presenting thymine (T) and pyrene (Py) units, that displayed excellent thermal properties after thermal curing, because its T moieties increased the physical cross-linking density. Second, we prepared Py-Bz-T/OBA-POSS [octuply adenine (A)-functionalized POSS] nanocomposites and investigated, using nuclear magnetic resonance and Fourier transform infrared spectroscopies, the multiple hydrogen bonding AT interactions between Py-Bz-T and OBA-POSS. Finally, we prepared Py-Bz-T/OBA-POSS/SWCNT ternary hybrid complexes dispersed in THF, stabilized through both multiple hydrogen bonding and π-π stacking interactions. Transmission electron microscopy revealed that the SWCNTs were highly dispersed and covered by the Py-Bz-T/OBA-POSS nanocomposites; these ternary hybrid complexes were stabilized through π-π interactions between Py-Bz-T/OBA-POSS and the SWCNTs, as evidenced using fluorescence spectroscopy.

Multivalent photo-crosslinkable coumarin-containing polybenzoxazines exhibiting enhanced thermal and hydrophobic surface properties

Mono-, bi-, and trivalent coumarin-containing benzoxazine monomers were synthesized by facile Mannich reactions of 4-methyl-7-hydroxycoumarin and paraformaldehyde with aniline, bisphenol A–NH₂, and 1,3,5-tri(4-aminobenzene).

Studies on graphene oxide–reinforced polybenzoxazine nanocomposites

In the present work, different weight percentages (1, 3, and 5 wt%) of benzoxazine-functionalized graphene oxide (FGO) were reinforced with polybenzoxazine (PBZ) matrix by means of ring-opening polymerization. The resulting nanocomposites were characterized for their thermal, mechanical, dielectric, and optical properties using different analytical techniques. From the results of these studies, it was observed that the 5 wt% FGO-reinforced PBZ composite shows an improved glass transition temperature, thermal stability, and dielectric constant to the extent of 18%, 39%, and 197%, respectively, when compared with those of neat PBZ matrix. Furthermore, 5 wt% FGO-reinforced PBZ composite also exhibits an enhanced ultraviolet shielding efficiency (88%), with improved tensile strength (52%) compared with those of neat PBZ matrix. The enhanced properties may be due to homogeneous and uniform distribution of FGO into the PBZ matrix, which was confirmed from scanning electron microscopic and high-resolution transmission electron microscopic images. Data obtained from these studies indicate that the developed nanocomposites with high dielectric constant can be used in the form of coatings, sealants, and encapsulates for high-performance dielectric as well as antistatic applications.

Thermal property of an aggregation-induced emission fluorophore that forms metal–ligand complexes with Zn(ClO4)2 of salicylaldehyde azine-functionalized polybenzoxazine

A salicylaldehyde azine-functionalized benzoxazine monomer formed zinc ion complexes not only improved the thermal properties but also facilitated ring-opening polymerization.

Studies on dielectric properties of GO reinforced bisphenol-Z polybenzoxazine hybrids

The value of the dielectric constant of bisphenol-Z (BPZ) polybenzoxazine (PBz) material was reduced by the reinforcement of graphene oxide into the BPZ-PBz matrix by exploiting the concept of polarization to enable its usage as a dielectric in microelectronics applications.

Thermal, mechanical and antibacterial properties of cyclophosphazene incorporated benzoxazine blended bismaleimide composites

Cyclophosphazene is incorporated in to Bz–Bmi composites in order to improve the thermal, mechanical, electrical resistance and antibacterial properties of CP–Bz–Bmi composite.

Effect of phenol on the synthesis of benzoxazine

The kinetic parameters of benzoxazine synthesis approximately equaled those of phenol consumption revealing that phenol was the key starting material.

A flexible insulator of a hollow SiO2 sphere and polyimide hybrid for flexible OLEDs

A hollow SiO₂ sphere and polyimide hybrid with a low dielectric constant and high thermal stability is useful for flexible insulators.