Silicone Polyoxamide Copolymers With Controlled Hard Segments
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Solution Overview
Problem
Siloxane polymers lack sufficient tensile strength, and existing methods for producing siloxane-based polyamide copolymers face challenges in achieving high degrees of polymerization and controlling the distribution of hard segments, leading to undesirable rheological characteristics and limited application in adhesives.
Innovation Solution
The development of silicone polyoxamide and silicone polyoxamide-hydrazide copolymers with controlled hard and soft segments, achieved through a method involving the reaction of oxalate esters with polydiorganosiloxane diamines and diamines, allowing for the formation of copolymers suitable for pressure-sensitive adhesives and mounting articles with improved shear strength and peel adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polydiorganosiloxanes and polyamides are combined to form block copolymers to improve tensile strength, then the tensile strength increases, but the solubility parameter mismatch makes it difficult to achieve high degrees of polymerization and control hard segment distribution
Solution Approach 1:
The patent employs an oxalate ester as an intermediary substance that facilitates the reaction between polydiorganosiloxane diamines and diamines. The oxalate ester acts as a soluble precursor that overcomes the solubility parameter mismatch between polydiorganosiloxanes and polyamides, enabling high degrees of polymerization while maintaining control over hard segment distribution in the final copolymer structure.
2Reliability
If known methods are used to produce siloxane-based polyamides, then copolymers can be formed, but the process requires multiple steps and excess materials to achieve desired copolymer structure
Solution Approach 1:
The patent applies preliminary action by pre-forming the oxalate ester intermediate before the main copolymerization reaction. This preliminary step creates a reactive intermediate that simplifies the subsequent reaction, reducing the number of process steps required and eliminating the need for excess materials while ensuring reliable copolymer structure formation.
Solution Approach 2:
The patent merges multiple process steps into a streamlined sequence by combining the formation of the oxalate ester intermediate with the subsequent copolymerization reaction. This integration reduces the overall number of discrete steps and material handling operations required to produce the desired copolymer structure.
3Quantity of substance
If polydiorganosiloxane segments are made longer to improve soft segment properties, then the fraction of soft segments increases, but the solubility parameter mismatch becomes more severe and high degree of polymerization becomes difficult to achieve
Solution Approach 1:
The oxalate ester intermediary enables the incorporation of longer polydiorganosiloxane segments (higher p values) into the copolymer structure by providing a soluble reaction pathway that overcomes the solubility parameter mismatch. This allows achieving high degrees of polymerization even with extended soft segments, maintaining both the desired soft segment fraction and polymerization degree.
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 copolymers exhibit enhanced shear strength, improved peel adhesion, and are well-suited for adhesive compositions, including pressure-sensitive and heat-activated adhesives, with reduced material and step requirements, offering better performance in mounting and release applications.
Implementation Method 1
Polydiorganosiloxane polyamides have been prepared by condensation reactions of amino terminated silicones with short-chained dicarboxylic acids. Alternatively, these copolymers have been prepared by condensation reactions of carboxy terminated silicones with short-chained diamines.
Data Source
AI summary
Silicone polyoxamide and silicone polyoxamide-hydrazide copolymers made by the method of the present invention comprise at least two repeating units of formula IIn this formula, each R1 is independently an alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with an alkyl, alkoxy, or halo; each Y is independently an alkylene, aralkylene, or a combination thereof; each G is independently a bond or a divalent residue equal to a diamine of formula R3HN—G—NHR3 minus the two —NHR3 groups; each R3 is independently hydrogen or alkyl or R3 taken together with G and with the nitrogen to which they are both attached form a heterocyclic group; each n is independently an integer of 0 to 300; each p is independently an integer of 1 to 25, and the average of p is 1.3 or greater; and each q is independently an integer of 1 to 2, and the average of q is no greater than 1.05.