Aluminum Nitride Particle Shell for Hydrolytic Stability

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Solution Overview

Problem

Aluminum nitride particles are hydrolytically unstable and decompose in water, making them unsuitable for applications where contact with water is likely, despite their attractive thermal conductivity properties.

Innovation Solution

Modified aluminum nitride particles are created with a crosslinked organic polymer shell using an aqueous acidic mixture and surfactant, where hydrophobic free-radically polymerizable monomers are added and polymerized to form a stable shell around the aluminum nitride core, enhancing stability in moist environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If aluminum nitride particles are used as thermal filler, then thermal conductivity is improved, but hydrolytic stability deteriorates causing decomposition in water

Engineering Contradiction:

Improvethermal conductivityVSAvoidhydrolytic stability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent creates a composite particle structure consisting of an aluminum nitride core surrounded by a polymer shell. This composite structure allows the inner core to provide high thermal conductivity while the outer shell provides hydrolytic stability, resolving the contradiction between thermal performance and chemical stability in moist environments

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies a thin polymer shell around the aluminum nitride core to protect it from water contact. This shell acts as a protective barrier that prevents hydrolysis while allowing the underlying aluminum nitride to maintain its thermal conductivity properties

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If a polymer shell is added to protect aluminum nitride particles, then hydrolytic stability is improved, but particle complexity increases

Engineering Contradiction:

Improvehydrolytic stabilityVSAvoidparticle structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses a thin polymer shell rather than a complex multi-layer structure. This simple shell design provides adequate protection against hydrolysis while minimizing the increase in structural complexity, making the modified particles practical for commercial applications

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The composite structure of core and shell is a straightforward two-component system that balances protection needs with manufacturing simplicity. The clear distinction between the aluminum nitride core and polymer shell facilitates easy synthesis and quality control

Inventive Principle:

Principle #40Composite materials

3Reliability

If crosslinked organic polymer shell is formed around aluminum nitride core, then stability in moist environments is improved, but manufacturing process complexity increases

Engineering Contradiction:

Improvestability in water and moist environmentsVSAvoidmanufacturing process simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent performs the polymerization reaction in an aqueous medium that already contains the aluminum nitride particles. This preliminary setup allows the polymer shell to form directly on the particle surfaces during a single processing step, rather than requiring separate coating and curing operations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses an aqueous polymerization medium as an intermediary to facilitate shell formation. Water serves as the reaction medium that allows monomers to polymerize on the particle surfaces, creating the protective shell without requiring organic solvents or complex equipment

Inventive Principle:

Principle #24Intermediary (Mediator)

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 modified particles exhibit improved stability in water and other moist environments, making them suitable for use as thermal fillers, electrically-insulating fillers, and abrasive particles while maintaining thermal conductivity.

Implementation Method 1

adding a free-radical initiator to the free-radically polymerizable mixture thereby polymerizing at least a portion of the hydrophobic free-radically polymerizable monomer to form the modified aluminum nitride particles

Methodology Applied

Scientific EffectFree-radical polymerization: Photopolymerisation

Implementation Method 2

at least a portion of the at least one hydrophobic free-radically polymerizable monomer is disposed in a surfactant bilayer that is disposed on the aluminum nitride particles

Methodology Applied

Scientific EffectSurfactant self-assembly: Surfactant

Data Source

PatentUS11492495B2Modified aluminum nitride particles and methods of making the same

Publication Date: 2022.11.08 3M INNOVATIVE PROPERTIES CO

AI summary

A modified aluminum nitride particle comprises an aluminum nitride core and a shell surrounding the aluminum nitride core. The shell comprises a crosslinked organic polymer. Methods of making the modified aluminum nitride particle by admicellar polymerization are also disclosed.