Curable Composition Silane Diluent Reduces Curling Flexible Waveguides

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Solution Overview

Problem

Cationic polymerizable compositions used for fabricating flexible waveguides face issues such as curling and separation due to differences in thermal expansion coefficients between the flexible substrate and the cured layer, leading to deformation, buckling, and crack formation.

Innovation Solution

A curable composition comprising a cationic polymerizable material and a diluent component with a silane compound having a single silicon-bonded cationic polymerizable group, which reduces cross-link density and prevents curling, while maintaining excellent physical properties like refractive index control and elasticity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If cationic polymerizable compositions are used to fabricate flexible waveguides, then flexibility is improved, but curling and separation occur due to thermal expansion mismatch

Engineering Contradiction:

ImproveflexibilityVSAvoiddimensional stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent modifies the chemical composition parameters of the curable composition by incorporating specific silane compounds (such as γ-glycidoxypropylmethyldimethoxysilane and γ-glycidoxypropylphenyldimethoxysilane) at controlled concentrations (5-50 wt%). This changes the physical and chemical parameters of the cured layer, including its coefficient of thermal expansion, to better match the flexible substrate and reduce thermal stress during curing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite curable composition system that combines cationic polymerizable materials (epoxides, vinyl ethers) with specific silane compounds and photoinitiators. This composite formulation allows the cured layer to achieve both flexibility and dimensional stability by leveraging the complementary properties of different materials - the flexibility of the base polymer and the thermal stability of the silane-modified network.

Inventive Principle:

Principle #40Composite materials

2Strength

If high cross-link density is achieved in cured layer, then hardness and modulus are improved, but deformation and buckling occur on flexible substrates

Engineering Contradiction:

ImprovehardnessVSAvoidflatness

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

The patent carefully controls the cross-link density parameter by selecting silane compounds with specific functional groups and controlling their concentration in the composition. The silane-modified epoxide/vinyl ether system achieves optimal cross-linking that provides sufficient hardness while maintaining flexibility and preventing buckling, balancing mechanical strength with shape stability.

Inventive Principle:

Principle #35Parameter changes

3Strength

If curable composition is applied on flexible substrate, then adhesion is improved, but separation and curling occur after curing

Engineering Contradiction:

ImproveadhesionVSAvoidbond stability

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent modifies the adhesion parameters by incorporating silane compounds that can form strong chemical bonds with both the flexible substrate and the cured polymer matrix. The silane functional groups (such as methoxysilane) undergo hydrolysis and condensation to create covalent bonding networks that anchor the cured layer to the substrate, maintaining bond stability even under thermal stress.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively prevents curling and deformation, ensuring the cured articles have excellent physical properties, including hardness, elasticity, and high light transmittance, suitable for various optical applications without the formation of cracks.

Implementation Method 1

curable composition comprising a cationic polymerizable material and a diluent component comprising a silane compound having a single silicon-bonded cationic polymerizable group

Methodology Applied

Scientific EffectCationic polymerization: Photopolymerisation

Data Source

PatentUS10435585B2Curable composition, method of preparing cured article, and cured article formed thereby

Publication Date: 2019.10.08 DOW SILICONES CORP

AI summary

A curable composition comprises a cationic polymerizable material. The curable composition further comprises a diluent component comprising a silane compound having a single silicon-bonded cationic polymerizable group. A method of forming a cured article with the curable composition is also disclosed. The method comprises applying the curable composition on a substrate to form a film. The method further comprises curing the film on the substrate to form the cured article. The present invention also provides the cured article formed in accordance with the method.