BNNT Aqueous Dispersion Stability via Tip Sonication and PVA

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Solution Overview

Problem

Boron nitride nanotubes (BNNTs) tend to easily entangle and aggregate due to their high aspect ratio and strong van der Waals interactions, limiting their stability and applicability in composite materials and devices.

Innovation Solution

A tip sonication-assisted hydrolysis method using a non-toxic surfactant like polyvinyl alcohol (PVA) in water as a solvent to disperse BNNTs, achieving long-term stability and preventing agglomeration, allowing for scalable and environmentally friendly production of stable BNNT dispersions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If BNNTs are dispersed in solvent without surfactant, then the dispersion process is simple, but the BNNTs easily entangle and aggregate due to strong van der Waals interactions

Engineering Contradiction:

Improvedispersion process simplicityVSAvoiddispersion stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

A non-toxic surfactant is introduced as an intermediary substance between BNNTs and solvent. The surfactant molecules adsorb onto BNNT surfaces through their hydrophobic tails while their hydrophilic heads interact with the aqueous solvent, creating a steric barrier that prevents van der Waals aggregation and maintains long-term dispersion stability without requiring complex manufacturing processes

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system forms a composite structure where surfactant molecules coat the BNNT surfaces, creating a core-shell configuration. The BNNT core maintains its structural integrity while the surfactant shell provides steric stabilization and compatibility with the aqueous solvent, enabling stable dispersions that combine the advantages of both components

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If tip sonication is used to disperse BNNTs, then long term stability is achieved, but the processing time and energy consumption increase

Engineering Contradiction:

Improvedispersion stabilityVSAvoidprocessing time

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The surfactant is pre-dissolved in the solvent before adding BNNTs, creating a ready-to-disperse medium. This preliminary preparation ensures that surfactant molecules are immediately available to coat BNNT surfaces upon contact, reducing the time required for effective dispersion and minimizing aggregation during the sonication process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The surfactant is used in excess relative to the BNNT surface area, ensuring complete coverage and stabilization of all BNNT surfaces. This excess surfactant continues to provide steric stabilization during and after sonication, reducing the required sonication time while maintaining long-term dispersion stability

Inventive Principle:

Principle #16Partial or excessive action

3Stability of the object's composition

If organic solvents are used to disperse BNNTs, then good dispersion is achieved, but toxic residues remain requiring further purification

Engineering Contradiction:

Improvedispersion stabilityVSAvoidtoxic residues

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The solvent type is changed from organic to aqueous, fundamentally altering the chemical parameters of the dispersion system. This parameter change eliminates toxic organic residues while maintaining dispersion stability through the combined action of the surfactant and water, removing the need for additional purification steps

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The surfactant is selected to be water-soluble and biodegradable, allowing the entire dispersion system to be safely disposed of or used directly in applications without requiring recovery or extensive purification. The surfactant's temporary role in stabilization is sufficient to enable direct application

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method provides BNNT dispersions with up to 100% stability for several months, enabling direct use in various applications without further purification, reducing processing difficulties and chemical compatibility issues, and improving mechanical and thermal properties when integrated into composites.

Implementation Method 1

performing a tip sonication process on the container with the solvent and the BNNTs to disperse the BNNTs in the solvent

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

dissolving a surfactant in the solvent before performing the tip sonication process, the surfactant being a non-toxic, non-hazardous surfactant

Methodology Applied

Scientific EffectSurfactant action: Surfactant

Data Source

PatentUS11584840B1Long term stable boron nitride nanotube aqueous dispersions

Publication Date: 2023.02.21 FLORIDA INTERNATIONAL UNIVERSITY

AI summary

Boron nitride nanotube (BNNT) dispersions and methods of fabricating the same are provided. Tip sonication-assisted hydrolysis can be utilized, with a dispersant/surfactant (e.g., polyvinyl alcohol (PVA)). The fabrication process can be used to obtain large scale BNNT dispersions with long term stability (e.g., stability for at least 3 months, at least 4 months, at least 5 months, at least 6 months, or about 6 months).