Monodisperse Colloidal Arrays with Steric Stabilization

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Solution Overview

Problem

Conventional crystalline colloidal arrays (CCAs) in coating compositions face challenges in self-assembly due to interference from charged species and extraneous materials, leading to premature particle agglomeration and destabilization, which prevents the formation of ordered structures necessary for effective radiation diffraction.

Innovation Solution

The use of monodisperse particles with a maximum particle size dispersity of 10% and a minimum surface charge density of 1 μC/cm2, combined with pendant steric stabilizing groups, allows these particles to self-assemble into crystalline colloidal arrays within coating compositions, even in conductive environments, enabling efficient radiation diffraction without the need for pre-treatment or additional processing steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional particles are used in coating compositions, then the coating can be applied, but the particles undergo premature agglomeration and destabilization due to interference from charged species and extraneous materials, preventing formation of ordered crystalline structures

Engineering Contradiction:

Improvestability of particle dispersionVSAvoidordered structure formation

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces sterically stabilizing groups as intermediary protective layers on particle surfaces. These groups act as mediators that prevent direct interaction between charged particle surfaces and destabilizing charged species in the coating composition, thereby maintaining dispersion stability and enabling ordered CCA formation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies particle surface properties by adding sterically stabilizing groups and controlling surface charge density within a specific range (0.1-10 μC/cm²). These parameter changes make particles resistant to agglomeration in conductive environments while maintaining monodispersity for crystalline structure formation

Inventive Principle:

Principle #35Parameter changes

2Reliability

If particles with high surface charge density are used, then electrostatic stabilization is improved, but premature agglomeration occurs due to interaction with charged species in the coating composition

Engineering Contradiction:

Improveelectrostatic stabilizationVSAvoidpremature agglomeration

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent optimizes the surface charge density parameter to a specific range (0.1-10 μC/cm²) that provides sufficient electrostatic stabilization while minimizing harmful interactions with charged species in the coating environment, thus preventing premature agglomeration

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite particle structures combining charged cores with sterically stabilizing surface groups. This composite approach maintains electrostatic stabilization from the charged core while the steric groups provide protective shielding against agglomeration

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If monodisperse particles with steric stabilizing groups are used, then self-assembly into crystalline colloidal arrays is enabled, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvemonodispersity of particlesVSAvoidparticle synthesis process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent incorporates sterically stabilizing groups during the particle synthesis process itself, rather than adding them as a separate post-processing step. This preliminary action simplifies the overall manufacturing process while achieving the required monodispersity and stabilization

Inventive Principle:

Principle #10Preliminary action

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

This approach enables the formation of stable crystalline colloidal arrays that exhibit a 'clean' color effect and angle-dependent color properties, providing a consistent and cost-effective alternative to traditional colorants in multi-layered coating systems, while maintaining the ability to diffract radiation across various electromagnetic spectra.

Implementation Method 1

monodisperse particles with a maximum particle size dispersity of 10% and a minimum surface charge density of 1 μC/cm2

Methodology Applied

Scientific EffectElectrostatic interaction: Electrostatics

Implementation Method 2

comprising pendant steric stabilizing groups

Methodology Applied

Scientific EffectSteric stabilization:

Implementation Method 3

These crystalline structures have been used for filtering narrow bands of selected wavelengths from a broad spectrum of incident radiation

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 4

crystalline structures having lattice spacings that are comparable to the wavelength of ultraviolet, visible, or infrared radiation

Methodology Applied

Scientific EffectBragg diffraction: Bragg Diffraction

Data Source

PatentUS9688880B2In situ assembled crystalline colloidal arrays

Publication Date: 2017.06.27 PPG INDUSTRIES OHIO INC

AI summary

A dispersion of monodisperse similarly charged particles, the monodisperse particles having a maximum particle size dispersity of 10% and each particle having a surface with a minimum surface charge density of 1 μC/cm2 and comprising pendant steric stabilizing groups.