scholarly journals Dielectric Properties of Shrinkage-Free Poly(2-Oxazoline) Networks from Renewable Resources

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1263
Author(s):  
Fabio Blaschke ◽  
Philipp Marx ◽  
Stefan Hirner ◽  
Inge Mühlbacher ◽  
Karin Wewerka ◽  
...  
Keyword(s):  
Renewable Resources ◽  
Hexagonal Boron Nitride ◽  
Low Loss ◽  
Polyamide 12 ◽  
Double Ring ◽  
Volumetric Expansion ◽  
Relative Expansion ◽  
Ring Opening Reaction ◽  
Lower Extent ◽  
Thermally Triggered

In the course of this study, the dielectric and physicochemical properties of poly(2-oxazoline) (POx) networks from renewable resources were compared with those of fossil-based polyamide 12 (PA 12) networks. POx was synthesized by the energy-efficient, microwave-assisted copolymerization of 2-oxazoline monomers, which were derived from fatty acids of coconut and castor oil. For the preparation of composites, aluminum nitride nanoparticles n-AlN and microparticles μ-AlN as well as hexagonal boron nitride BN submicroparticles were used. Additionally, 0, 15, or 30 wt.% of a spiroorthoester (SOE) were added as an expanding monomer aiming to reduce the formation of shrinkage-related defects. For the crosslinking of the polymers and the SOE as well as the double ring-opening reaction of the SOE, a thermally triggered dual-cure system was developed. The fully-cured blends and composites containing SOEs exhibited lower densities than their fully-cured SOE-free analogues, which was indicative of a lower extent of shrinkage (or even volumetric expansion) during the curing reaction, which is referred to as relative expansion RE. The RE amounted to values in the range of 0.46 to 2.48 for PA 12-based samples and 1.39 to 7.50 vol.% for POx-based samples. At 40 Hz, the “green” POx networks show low loss factors, which are competitive to those of the fossil-based PA 12.

scholarly journals Expanding Monomers as Anti-Shrinkage Additives

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 806
Author(s):  
Philipp Marx ◽  
Frank Wiesbrock
Keyword(s):  
Ring Opening ◽  
Covalent Bond ◽  
Volumetric Shrinkage ◽  
Structure Property ◽  
Atomic Packing ◽  
Materials Properties ◽  
Volumetric Expansion ◽  
Structure Property Relationships ◽  
Ring Opening Reaction ◽  
Measuring Techniques

Commonly, volumetric shrinkage occurs during polymerizations due to the shortening of the equilibrium Van der Waals distance of two molecules to the length of a (significantly shorter) covalent bond. This volumetric shrinkage can have severe influence on the materials’ properties. One strategy to overcome this volumetric shrinkage is the use of expanding monomers that show volumetric expansion during polymerization reactions. Such monomers exhibit cyclic or even oligocyclic structural motifs with a correspondingly dense atomic packing. During the ring-opening reaction of such monomers, linear structures with atomic packing of lower density are formed, which results in volumetric expansion or at least reduced volumetric shrinkage. This review provides a concise overview of expanding monomers with a focus on the elucidation of structure-property relationships. Preceded by a brief introduction of measuring techniques for the quantification of volumetric changes, the most prominent classes of expanding monomers will be presented and discussed, namely cycloalkanes and cycloalkenes, oxacycles, benzoxazines, as well as thiocyclic compounds. Spiroorthoesters, spiroorthocarbonates, cyclic carbonates, and benzoxazines are particularly highlighted.

scholarly journals Miniaturizing transmon qubits using van der Waals materials

2021 ◽  
Author(s):  
Abhinandan Antony ◽  
Martin Gustafsson ◽  
Guilhem Ribeill ◽  
Matthew Ware ◽  
Anjaly Rajendran ◽  
...  
Keyword(s):  
Parallel Plate ◽  
Hexagonal Boron Nitride ◽  
Van Der Waals ◽  
Spatial Density ◽  
Quantum Computers ◽  
Low Loss ◽  
Quantum Devices ◽  
Lossy Dielectrics ◽  
Circuit Components ◽  
High Coherence

Abstract Quantum computers can potentially achieve an exponential speedup versus classical computers on certain computational tasks, recently demonstrated in systems of superconducting qubits. However, the capacitor electrodes that comprise these qubits must be large in order to avoid lossy dielectrics. This tactic hinders scaling by increasing parasitic coupling among circuit components, degrading individual qubit addressability, and limiting the spatial density of qubits. Here, we take advantage of the unique properties of van der Waals (vdW) materials to reduce the qubit area by $>1000$ times while preserving the required capacitance without increasing substantial loss. Our qubits combine conventional aluminum-based Josephson junctions with parallel-plate capacitors composed of crystalline layers of superconducting niobium diselenide and insulating hexagonal-boron nitride. We measure a vdW transmon $T_1$ relaxation time of 1.06 $\mu$s, which demonstrates a path to achieve high-qubit-density quantum processors with long coherence times, and the broad utility of layered heterostructures in low-loss, high-coherence quantum devices.

scholarly journals Edge-oriented and steerable hyperbolic polaritons in anisotropic van der Waals nanocavities

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhigao Dai ◽  
Guangwei Hu ◽  
Guangyuan Si ◽  
Qingdong Ou ◽  
Qing Zhang ◽  
...  
Keyword(s):  
Figure Of Merit ◽  
Degrees Of Freedom ◽  
Optical Axis ◽  
Hexagonal Boron Nitride ◽  
Van Der Waals ◽  
Real Space ◽  
Crystallographic Direction ◽  
Tuning Parameter ◽  
Low Loss ◽  
Plane Anisotropy

AbstractHighly confined and low-loss polaritons are known to propagate isotropically over graphene and hexagonal boron nitride in the plane, leaving limited degrees of freedom in manipulating light at the nanoscale. The emerging family of biaxial van der Waals materials, such as α-MoO3 and V2O5, support exotic polariton propagation, as their auxiliary optical axis is in the plane. Here, exploiting this strong in-plane anisotropy, we report edge-tailored hyperbolic polaritons in patterned α-MoO3 nanocavities via real-space nanoimaging. We find that the angle between the edge orientation and the crystallographic direction significantly affects the optical response, and can serve as a key tuning parameter in tailoring the polaritonic patterns. By shaping α-MoO3 nanocavities with different geometries, we observe edge-oriented and steerable hyperbolic polaritons as well as forbidden zones where the polaritons detour. The lifetime and figure of merit of the hyperbolic polaritons can be regulated by the edge aspect ratio of nanocavity.

A High Finesse Serial Coupled Microresonator Filter

2020 ◽  
Vol 41 (2) ◽  
pp. 117-123
Author(s):  
Jyoti Kedia ◽  
Neena Gupta
Keyword(s):  
Ring Resonator ◽  
Q Factor ◽  
Round Trip ◽  
Low Loss ◽  
Double Ring ◽  
High Finesse

AbstractA serially coupled double-ring resonator using the low loss multilayer silicon wire waveguide is presented that has featured high out-of-band rejection and high finesse. The round trip loss and Q factor has also been calculated and found moderate. However, extremely low loss waveguide has shown reduced coupling between the ring and the waveguide.

Manipulating phonon polaritons in low loss 11B enriched hexagonal boron nitride with polarization control

Nanoscale ◽  
2020 ◽  
Vol 12 (15) ◽  
pp. 8188-8193 ◽  
Author(s):  
Lu Wang ◽  
Runkun Chen ◽  
Mengfei Xue ◽  
Song Liu ◽  
James H. Edgar ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Low Loss ◽  
Polarization Control ◽  
Phonon Polaritons

An effective approach to reducing phonon polariton damping and manipulating phonon polariton excitation in hBN via polarization control.

Synthesis of New Benzoxazine from Cardanol-Furfural Resin and the Properties of the Corresponding Polymer

2011 ◽  
Vol 236-238 ◽  
pp. 317-320 ◽  
Author(s):  
Sheng Fang Li ◽  
Wei Dong Huang
Keyword(s):  
Renewable Resources ◽  
Ring Opening ◽  
Phenolic Resin ◽  
Raw Materials ◽  
Side Chain ◽  
H Nmr ◽  
Ring Opening Reaction ◽  
Yield Value ◽  
Good Heat Resistance ◽  
Good Heat

A novel benzoxazine-based phenolic resin containing furan groups and long alkyl side-chain (CFB) was synthesized using cardanol-furfural resin as phenolic raw materials. The new benzoxazine-based cardanol-furfural resin derived from renewable resources was characterized by FTIR,1H NMR spectra and Differential scanning calorimeter (DSC) etc. The thermal ring-opening reaction of the benzoxazine ring and the polymerization of the double bond were demonstrated with FTIR measurement. The thermal behavior of the cured product was also investigated with thermogravimetric analysis. The corresponding polybenzoxazine showed Tgvalue higher than that of polybenzoxazine prepared from cardanol, ammonia and formaldehyde. The char yield value at 800°C of the corresponding polybenzoxazine is 46.2% in N2atmosphere. The results showed that the polybenzoxazine cured from CFB had good heat resistance and toughness.

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