Polymerizable Silicone Copolyol Macromers via Citraconate Esterification
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Solution Overview
Problem
The synthesis of silicone-containing macromers with terminal or pendant unsaturation is challenging due to compatibility issues with polar polymers and the difficulty in incorporating dimethicone copolyols into polymer backbones, leading to phase separation and inefficient copolymerization.
Innovation Solution
A process involving the reaction of dimethicone copolyols with itaconic anhydride to form citraconate esters, which are then copolymerized with other monomers, allowing for the creation of polymers with desirable properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dimethicone copolyols are incorporated into polymer formulations, then surfactant properties and sensory characteristics are improved, but compatibility with polar polymers deteriorates leading to phase separation
Solution Approach 1:
The patent merges the dimethicone copolyol backbone with polar polymer chains through covalent bonding during polymerization. The siloxane units are incorporated into the polymer backbone rather than remaining as separate additives, creating a unified structure that combines the surfactant properties of dimethicone with the polarity of the polymer chains, thereby eliminating phase separation while maintaining both functional characteristics.
Solution Approach 2:
The invention creates a composite polymer structure where siloxane units are integrated within a polar polymer matrix. This composite architecture allows the material to exhibit both the water and oil repellency characteristic of dimethicone and the polarity needed for compatibility with polar polymers, achieving a synergistic effect that resolves the compatibility issue.
2Stability of the object's composition
If dimethicone copolyols are covalently incorporated into polymer backbones, then compatibility is improved, but copolymerization efficiency deteriorates due to chain transfer
Solution Approach 1:
The patent modifies the chemical parameters of the dimethicone copolyol by introducing specific functional groups and controlling molecular weight and architecture. These parameter changes reduce the chain transfer constant during polymerization, allowing efficient copolymerization while maintaining covalent incorporation into the polymer backbone for improved compatibility.
Solution Approach 2:
The invention performs preliminary modification of the dimethicone copolyol structure before polymerization to reduce chain transfer tendencies. By pre-functionalizing the copolyol with specific groups that are less prone to chain transfer, the patent enables efficient copolymerization while ensuring covalent incorporation, thus resolving the efficiency problem.
3Manufacturing precision
If vinyl terminated siloxane macromers are synthesized via anionic polymerization, then controlled molecular weight is achieved, but synthesis difficulty and purification complexity increase
Solution Approach 1:
The patent replaces the complex anionic polymerization mechanism with free radical polymerization. This substitution simplifies the synthesis process and purification requirements while still achieving controlled molecular weight through careful selection of initiators and reaction conditions, thereby reducing the complexity associated with vinyl terminated siloxane macromer synthesis.
Solution Approach 2:
The invention uses readily available, easily handled free radical initiators instead of complex anionic polymerization systems. This approach employs simpler, more forgiving reagents that are easier to control and purify, reducing the synthesis and purification complexity while maintaining the ability to achieve controlled molecular weight through standard polymerization techniques.
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 synthesis of easily purified silicone macromers that can be readily copolymerized, resulting in polymers with improved properties such as water repellency, lubricity, and sensory characteristics.
Implementation Method 1
The reaction of a hydroxyl silicone compound such as dimethicone copolyol with a cyclic anhydride is known. As disclosed in U.S. Patent Nos. 3,560,544 and 5,296,625 the reaction of the active hydroxyl group(s) on the copolyol with the anhydride yields the copolyol half-ester of the anhydride.
Implementation Method 2
In the reaction medium comprising a dimethicone copolyol (DMC-OH) and itaconic anhydride, the itaconic anhydride nearly instantaneously isomerizes to citraconic anhydride which then reacts with the copolyol to give the citraconate dimethicone copolyol ester
Implementation Method 3
The obtained macromer is homopolymerizable or copolymerizable with ethylenically unsaturated monomers.
Data Source
AI summary
A polymerizable dimethicone copolyol macromer composition is synthesized by reacting itaconic anhydride with a dimethicone copolyol. During the reaction itaconic anhydride spontaneously isomerizes to citraconic anhydride which in turn is esterified by the dimethicone copolyol. The obtained macromers are copolymerizable with olefinically unsaturated monomers. Polymers containing the macromer repeating units are useful in a variety of applications including personal care, textile and industrial formulations to deliver softness, lubricity, fixative, water repellency, gloss, surface modification, and surfactant properties.