Cyclic Branched Siloxanes Production via Equilibration and Phase Separation
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Solution Overview
Problem
Current methods for producing branched organomodified siloxanes face challenges in achieving uniform distribution of branching points and preserving hydrogen bonds, leading to issues with product quality and viscosity control, particularly in the presence of sensitive functional groups and high reactivity of M, D, and T units.
Innovation Solution
A process involving sour-catalyzed equilibration of trialkoxysilanes with siloxancyclen and α, ω-dihydroxy-polydimethylsiloxan, followed by hydrolysis and condensation, using silicon-containing solvents and distillative separation to achieve a high degree of condensation and simplify solvent recycling, resulting in cyclical-branched siloxanes with a controlled D/T unit ratio and improved processing characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct hydrolytic condensation of hydrogen-containing silanes is used, then the production process is simplified, but hydrogen siloxane is rejected and product quality deteriorates
Solution Approach 1:
The patent extracts and removes the problematic salt acid water phase containing rejected hydrogen siloxane through phase separation, allowing the desired siloxane product to be isolated in high purity while discarding the harmful byproducts
Solution Approach 2:
The patent introduces an organic auxiliary phase as an intermediary medium to facilitate the separation of hydrogen siloxane from the reaction mixture, enabling efficient phase separation and product purification without compromising product quality
2Shape
If trifunctional silanes are used to create branching within siloxane chains, then branching is achieved, but T-structured domains form and homogeneity deteriorates
Solution Approach 1:
The patent applies local quality by controlling the distribution of trifunctional silane units at specific positions within the siloxane chains, ensuring branching occurs at appropriate intervals rather than forming concentrated T-structured domains, thus maintaining overall homogeneity
Solution Approach 2:
The patent changes the parameter of trifunctional silane concentration and distribution during the condensation process to optimize branching while preventing excessive T-unit aggregation, achieving a balance between branching structure and compositional homogeneity
3Strength
If multiple networking of silicone blocks with organic block copolymer is carried out, then cross-linking is achieved, but viscosity increases unpredictably and control is difficult
Solution Approach 1:
The patent employs feedback control by monitoring the progression of hydrolysis and condensation reactions, adjusting reaction conditions in real-time to achieve desired cross-linking density while maintaining predictable viscosity characteristics
Solution Approach 2:
The patent performs preliminary hydrolysis and condensation steps before final networking, allowing gradual build-up of cross-linking structure and enabling better control over the final viscosity and mechanical properties of the organomodified siloxane
4Stability of the object's composition
If acid catalyst is used for equilibration of T-units, then branching distribution is improved, but sensitive functional groups are degraded
Solution Approach 1:
The patent changes the parameter of catalyst type and concentration, using controlled amounts of acid catalyst only when necessary for equilibration, and carefully controlling reaction temperature and time to minimize degradation of sensitive functional groups while achieving uniform branching distribution
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 process enables the production of cyclical-branched siloxanes with a high degree of condensation and easy further processing, reducing waste and environmental impact, while maintaining excellent storage stability and preventing premature hardening or degradation.
Implementation Method 1
A process involving sour-catalyzed equilibration of trialkoxysilanes with siloxancyclen and α, ω-dihydroxy-polydimethylsiloxan
Implementation Method 2
followed by hydrolysis and condensation
Implementation Method 3
hydrolysis and condensation, using silicon-containing solvents and distillative separation to achieve a high degree of condensation
Implementation Method 4
distillative separation to achieve a high degree of condensation and simplify solvent recycling
Data Source
AI summary
Mixtures of cyclic-branched siloxanes comprising exclusively D and T units, with the stipulation that the total fraction of D and T units present in the siloxane matrix, which have Si alkoxy and/or SiOH groups and can be determined by 29Si NMR spectroscopy, is less than 2.0, preferably less than 1.0 mol percent, are described, as well as branched, organomodified siloxanes obtainable therefrom.