Silyl-Terminated Polymer Sealants via Copper-Catalyzed Click Chemistry
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Solution Overview
Problem
Existing adhesives and sealants, particularly those using platinum-catalyzed hydrosilylation, are prone to inhibition by impurities like tin, sulfur, and amines, and lack flexibility in incorporating various functional groups, limiting their application and performance.
Innovation Solution
The development of silyl-terminated polymers linked via triazole moieties using click chemistry, which involves a cycloaddition reaction between alkyne and azide functional groups in the presence of a copper I catalyst, enabling the formation of one-part and two-part moisture-curable sealants and adhesives that are tolerant to impurities and compatible with diverse functional groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If platinum-catalyzed hydrosilylation is used for curing sealants and adhesives, then fast curing speed is achieved, but the system is easily inhibited by impurities such as tin, sulfur, and amines
Solution Approach 1:
The patent changes the chemical parameters of the curing system by replacing platinum catalyst with copper(I) catalyst and changing the reaction mechanism from hydrosilylation to click chemistry (azide-alkyne cycloaddition). This parameter change maintains fast curing speed while eliminating sensitivity to tin, sulfur, and amine impurities that inhibit platinum-catalyzed systems.
Solution Approach 2:
The patent substitutes the platinum-catalyzed hydrosilylation mechanism with a copper-catalyzed click chemistry mechanism. This substitution replaces the problematic platinum-based chemical system with a copper-based system that is tolerant to common impurities while maintaining the desired curing performance.
2Adaptability or versatility
If traditional adhesives and sealants are used, then formulation is relatively simple, but versatility in incorporating various functional groups is limited
Solution Approach 1:
The patent creates a universal platform chemistry where copper-catalyzed click chemistry can accommodate multiple different functional groups (azides, alkynes, strained alkynes) and various polymer backbones. This multi-functional approach allows the same basic reaction mechanism to work with diverse compositions, enhancing versatility without proportionally increasing formulation complexity.
Solution Approach 2:
The patent employs composite material strategies by combining silyl-terminated polymers with various functional groups and polymer backbones (polyether, polyester, polydimethyl siloxane, polymethyl methacrylate, polyacrylate, polybutadiene, or polysulfide). These composite formulations achieve high versatility in functional group incorporation while managing formulation complexity through systematic design.
3Reliability
If click chemistry with copper I catalyst is used, then impurity tolerance and versatility are improved, but additional catalyst and reaction conditions are required
Solution Approach 1:
The patent uses copper(I) catalyst, which is significantly cheaper than platinum catalyst, and can be used in lower quantities. The copper catalyst system, while requiring specific reaction conditions, offers cost-effective impurity tolerance and can be disposed of or deactivated more easily than precious metal catalysts, offsetting the added complexity.
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 provides high-yield, impurity-tolerant, and byproduct-free sealant and adhesive compositions with extended working time, allowing for versatile formulations and applications, including metal-free options suitable for electronics and medical uses, and on-demand curing capabilities.
Implementation Method 1
click chemistry, which involves a cycloaddition reaction between alkyne and azide functional groups in the presence of a copper I catalyst
Implementation Method 2
in the presence of a copper I catalyst
Implementation Method 3
hydrosilylation is often employed to form the silyl-modified polymers used in the moisture-curable sealants
Implementation Method 4
one-component sealants that are moisture cured
Data Source
AI summary
The invention described herein generally pertains to a composition that includes a silyl-terminated polymer having silyl groups linked to a polymer backbone via triazole. The silyl-terminated polymer is a reaction product of a functionalized polymer backbone and a functionalized silane. The polymer backbone includes a first functional group, which may be one of an azide or an alkyne. The functionalized silane includes a second functional group may also be one of an azide or an alkyne, but is also different from the first functional group. The functionalized polymer backbone is reacted with the functionalized silane in the presence of a metal catalyst.