Benzocyclobutene/vinylphenyl-introduced polycarbosilanes with low dielectric constant, high temperature performance and photopatternability

Advances in the Synthesis of Preceramic Polymers for the Formation of Silicon-Based and Ultrahigh-Temperature Non-Oxide Ceramics

Preceramic polymers (PCPs) are a group of specialty macromolecules that serve as precursors for generating inorganics, including ceramic carbides, nitrides, and borides. PCPs represent interesting synthetic challenges for chemists due to the elements incorporated into their structure. This group of polymers is also of interest to engineers as PCPs enable the processing of polymer-derived ceramic products including high-performance ceramic fibers and composites. These finished ceramic materials are of growing significance for applications that experience extreme operating environments (e.g., aerospace propulsion and high-speed atmospheric flight). This Review provides an overview of advances in the synthesis and postpolymerization modification of macromolecules forming nonoxide ceramics. These PCPs include polycarbosilanes, polysilanes, polysilazanes, and precursors for ultrahigh-temperature ceramics. Following our review of PCP synthetic chemistry, we provide examples of the application and processing of these polymers, including their use in fiber spinning, composite fabrication, and additive manufacturing. The principal objective of this Review is to provide a resource that bridges the disciplines of synthetic chemistry and ceramic engineering while providing both insights and inspiration for future collaborative work that will ultimately drive the PCP field forward.

Multilayer Dielectric Nanocomposites with Cross-Linked Dielectric Transition Interlayers for High-Temperature Applications

In energy storage and transportation systems, polymer dielectrics are widely applied in smart grids, electric vehicles, and power conditioning owing to their incomparable power density and high reliability. However, the dielectric constant (ε) and breakdown strength (E_b) normally cannot be increased simultaneously, which results in insufficient discharged energy density especially at high temperatures. In this work, enhanced E_b and high energy density are archived in multilayer polymer nanocomposites by introducing cross-linked dielectric transition layers. Specifically, the sandwiched composite achieves a huge discharge energy density of 4.64 J cm^-3 with a charged-discharged efficiency of 84% at 150 °C and 500 MV m^-1. The formation of cross-linked dielectric transition layers between layers of the multilayer nanocomposite could effectively restrain the growth of the electrical tree and greatly increase the E_b. This work presents a strategy for designing high-performance multilayered dielectric polymer nanocomposites by introducing cross-linked dielectric transition layers to reduce the loss from interlayer interfaces.

Thermally and Chemically Stable Isoporous Block Copolymer Membranes

Ultrafiltration (UF) membranes, particularly membranes fabricated from self-assembled diblock copolymers, hold promise in wastewater treatment, dairy, and food industries. Membrane development goals involve combining a highly porous selective layer with a narrow pore size distribution with a mechanically stable supporting layer to achieve constant flux. To date, isoporous integral asymmetric membranes have been formed either as flat sheets or hollow fibers, and a surface-selective layer determines membrane separation performance. A unique isoporous membrane of the poly(4-vinylbenzocyclobutene)-b-poly(4-vinylpyridine) (PVBCB-b-P4VP) diblock copolymer with a substructure of almost homogeneous porosity throughout the body of the material (three-dimensional porosity) has been developed. Moreover, the matrix of the membrane (PVCB) enables it to undergo cross-linking, allowing the membrane to be thermally sterilized and applied in high-temperature UF applications.

High Performance Low Dielectric Polybenzocyclobutene Nanocomposites with Organic-Inorganic Hybrid Silicon Nanoparticles

In this study, benzocyclobutene-functionalized organic-inorganic hybrid spherical silicon nanoparticles (BCBNPs) with controllable size (200-600 nm) and good dispersion were synthesized by one-step sol-gel method in aqueous solution. The effect of...

Low dielectric resins derived from hyperbranched carbosilane oligmers functionalized by benzocyclobutene groups

Polycarbosilanes have been considered as potential materials used in electronic packaging and circuit boards owing to their excellent low-dielectric performance. In this work, we prepared new hyperbranched carbosilane oligomers (HCBOs) which were functionalized by benzocyclobutene (BCB) groups. HCBOs can be thermally cured to produce transparent (HCBRs) with low dielectric constant and high thermostability.

Interface-Strengthened Polymer Nanocomposites with Reduced Dielectric Relaxation Exhibit High Energy Density at Elevated Temperatures Utilizing a Facile Dual Crosslinked Network

High-temperature ceramic/polymer nanocomposites with large energy density as the reinforcement exhibit great potential for energy storage applications in modern electronic and electrical power systems. Yet, a general drawback is that the increased dielectric constant is usually achieved at the cost of decreased breakdown strength, thus leading to moderate improvement of energy density and even displaying a marked deterioration under high temperatures and high electric fields. Herein, a new strategy is reported to simultaneously improve breakdown strength and discharged energy density by a step-by-step, controllable dual crosslinking process, which constructs a strengthened interface as well as reduces molecular chains relaxation under elevated temperatures. Great breakdown strength and discharged energy density is achieved in the dual crosslinked network BT-BCB@DPAES nanocomposites at elevated temperatures when compared to noninterfacial-strengthened, BT/DPAES composites, i.e., an enhanced breakdown strength and a discharged energy density of 442 MV m^-1 and 3.1 J cm^-3 , increasing by 66% and 162%, and a stable cyclic performance over 10 000 cycles is demonstrated at 150 °C. Moreover, the enhancement through the synergy of two crosslinked networks is rationalized via a comprehensive phase-field model for the composites. This work offers a strategy to enhance the electric storage performances of composites at high temperatures.

4-(2-Bromovinyl)benzocyclobutene

4-(2-Bromovinyl)benzocyclobutene was prepared via a five stage synthesis starting from benzocyclobutene in an overall 30% yield. 4-(2-Bromovinyl)benzocyclobutene has a potential applications in synthesis of monomers for dielectric materials.

Flexible and low-k polymer featuring hard–soft-hybrid strategy

One of the main challenges for dielectric materials for advanced microelectronics is their high dielectric value and brittleness. In this study, we adopted a hard–soft-hybrid strategy and successfully introduced a hard, soft segment and covalent crosslinked structural unit into a hybridized skeleton via copolymerization of polydimethylsiloxane (PDMS), benzocyclobutene (BCB) and double-decker-shaped polyhedral silsesquioxanes (DDSQ) by a platinum-catalyzed hydrosilylation reaction, thus producing a random copolymer (PDBD) with a hybridized skeleton in the main chain. PDBD exhibited high molecular weight and thermal curing action without any catalyst. More importantly, the cured copolymer displayed high flexibility, high thermal stability and low dielectric constant, evidencing its potential applications in high-performance dielectric materials.

Hard–Soft-hybrid strategy is used to synthesize random copolymers with a hybridized main chain.

Bicyclo[4.2.0]octa-1,3,5-trien-3-yl-dimethyl((E)-styryl)-silane

Bicyclo[4.2.0]octa-1,3,5-trien-3-yl-dimethyl-((E)-styryl)-silane was synthesized via three stage synthesis starting from benzocyclobutene and (2-bromo-vinyl)-benzene. The structure of the product was determined using 1H- and 13C-NMR and HRMS.

Synthesis and properties of benzocyclobutene-terminated imide-containing cyano group

Benzocyclobutene (BCB) resins have aroused much interest because of their excellent physical and chemical properties. Unfortunately the temperature required to induce cross-linking in typical BCBs is higher than 250°C, which restricts their applications. In this study, a novel cyano-containing BCB-terminated imide monomer was synthesized through the reaction of 1-cyano-5-amino-benzocyclobutene with 4,4′-oxydiphthalic anhydride. This monomer allows a 50–100°C lower curing temperature in comparison with typical BCBs, and it is highly soluble in various solvents and can easily convert to cured film at 150–200°C. Because of the presence of rigid imide group and strong polar cyano group, the cured film exhibits excellent mechanical strength with tensile strength up to 87.8 MPa, high glass transition temperature up to 350°C, low coefficient of thermal expansion (36.9 ppm K−1), and outstanding planarity with the average surface roughness as low as 0.26 nm.

Benzocyclobutene-functional double-decker silsesquioxane: self-assembled hybrid resin for high-performance dielectrics and LED encapsulants

The optoelectronic industry is focused on developing new electronic packaging materials to improve the performance of optoelectronic devices.

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.

Dendrimeric organosiloxane with thermopolymerizable –OCFCF2 groups as the arms: synthesis and transformation to the polymer with both ultra-low k and low water uptake

A novel fluoro-containing dendrimeric macromolecule with cyclic siloxane as the core and aryl-trifluorovinyl-ether (–OCFCF₂) units as the arms was reported.

Benzocyclobutene resin with m-carborane cages and a siloxane backbone: a novel thermosetting material with high thermal stability and shape-memory property

A simple and effective way to synthesize carborane-containing benzocyclobutene resin with excellent performances.