Poly(ether-thioether) Thiol Sealants With Acid-Stable Synthesis
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Solution Overview
Problem
Existing methods for preparing polymeric thiols are unsatisfactory due to high costs, complex handling, use of toxic materials, and lack of stability under acidic conditions, limiting their application in aerospace and aircraft sealants.
Innovation Solution
A new method involving a two-step process to produce thiol group containing poly(ether-thioether) species, using compounds like HO-R 3< -(S) s -R 4< -OH and HO-R 5< -OH, followed by reaction with inorganic hydrogen sulfide or organic dithiol, to create a composition suitable for sealants with improved stability and low-temperature curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thiol-ene click chemistry route is used to prepare polymeric thiols, then the polymerization efficiency is improved, but the cost increases and raw material availability is limited
Solution Approach 1:
The patent replaces expensive and scarce raw materials (bis-thioles and divinylethers) with cheap and readily available alternatives (polyhalides and bis-phenols). This substitution maintains polymerization efficiency while dramatically reducing costs and improving material availability, directly resolving the technical contradiction between productivity and ease of manufacture
Solution Approach 2:
The patent changes the chemical parameters of the starting materials from thiol-ene click chemistry components to polyhalide and bis-phenol components that undergo polycondensation. This parameter change enables the use of abundant, low-cost materials while achieving comparable polymerization efficiency through a different reaction mechanism
2Device complexity
If polyhalides such as bis-chloroethyl formal are used as starting materials, then the synthesis route is simplified, but the hazard potential and toxicity increase
Solution Approach 1:
The patent converts the harmful polyhalide starting materials into beneficial intermediates through controlled hydrolysis to form polyols, which then react with bis-phenols to produce the desired polymeric thiols. This transformation eliminates the toxicity and hazard potential of polyhalides while maintaining the simplicity of the synthesis route
Solution Approach 2:
The patent introduces polyols as intermediary substances that bridge the gap between simple starting materials and the final polymeric thiol product. These intermediates enable a stepwise synthesis approach that avoids direct use of toxic polyhalides, thereby simplifying the overall process while reducing harmful factors
3Productivity
If bis-chloroethyl formal is used in the synthesis, then the polymerization proceeds efficiently, but the resulting products lack stability under acidic conditions
Solution Approach 1:
The patent extracts and eliminates the formal group from the molecular structure by using alternative starting materials (polyols and bis-phenols) that do not contain this acid-labile moiety. This extraction of the harmful structural element maintains polymerization efficiency while conferring acid stability to the final product
Solution Approach 2:
Instead of introducing acid instability through formal groups during efficient polymerization, the patent inverts the approach by selecting starting materials and reaction conditions that inherently produce acid-stable polymers. The synthesis route is redesigned to build stability into the polymer backbone from the beginning, rather than adding it as a post-processing step
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 a safe, economical, and ecologically friendly process for producing polymeric thiols with enhanced acid stability, allowing for sealants with good mechanical properties and resistance to water and fuel, suitable for aerospace and aircraft applications.
Implementation Method 1
reaction with inorganic hydrogen sulfide or organic dithiol
Data Source
AI summary
The invention relates to a composition comprising thiol group containing poly(ether-thioether) species having the general structure [H(S-R1)p-S-(CH2)r-O]m-R2-O-[R3-(S)s-R4-O]-[R5-O]n-R6 (Ia) or being an R1-linked dimer thereof, wherein, R1 is an aliphatic or aromatic divalent organic residue, R2 is an aliphatic or aromatic (m+1)-valent organic residue, with m = 2 or 3, R3 and R4 are divalent residues (CHRa)t with t = 2 to 4, wherein residues Ra are selected from H and hydrocarbyl groups comprising 1 to 12, y of the n residues R5 are branched divalent hydrocarbon residue comprising 4 to 20 carbon atoms, with y being ≥ 1; z of the n residues R5 are residues R3-(S)s-R4, z being ≥ 1; with n = y + z; and n independently of each other being a number in the range from 2 to 200; R6 is H in case R5 is a branched divalent hydrocarbon residue comprising 4 to 20 carbon atoms, or R6 is H or R2-[O-(CH2)r-S-R1-SH]m in case R5 being a residue R3-(S)s-R4; and p = 0 or 1, r = 2 or 3, and s = 1 to 8. The invention further relates to a method of producing said polymers, an intermediate of said polymers and its production, sealing systems and sealants containing the inventive polymer, a method of sealing and a sealed substrate, as well as the use of the sealant in the aerospace and/or aircraft industry.