Silicone Polyoxamide Copolymers Hard Segment Control
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Solution Overview
Problem
Silicone polyoxamide and polyoxamide-hydrazide copolymers face challenges in achieving high tensile strength and thermal stability due to the difficulty in controlling the distribution and level of hard segments within the copolymer chain, leading to limitations in properties such as solvent resistance, modulus, and heat stability.
Innovation Solution
The development of silicone polyoxamide and silicone polyoxamide-hydrazide copolymers with random runs of hard segments, achieved through a method involving the reaction of an oxalate ester with a polydiorganosiloxane diamine and subsequent addition of diamines, allowing for improved control over the hard segment distribution and incorporation of reactive compounds like methyl ethyl ketone oxime, which enhances the copolymers' properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polydiorganosiloxane polyamides are prepared by condensation reactions of amino terminated silicones with short-chained dicarboxylic acids, then the copolymers can be formed, but the degrees of polymerization are limited and the fraction of polydiorganosiloxane soft segments is low
Solution Approach 1:
The patent divides the copolymer into distinct soft segments (polydiorganosiloxane) and hard segments (polyamide), creating a block copolymer structure. This segmentation allows each segment to be optimized independently - the soft segments provide flexibility and elastomeric properties while the hard segments provide tensile strength and thermal stability.
Solution Approach 2:
The patent creates a composite material system combining polydiorganosiloxane and polyamide segments in a single copolymer chain. This composite structure leverages the complementary properties of both materials: the low glass transition temperature and flexibility of siloxane combined with the high tensile strength and thermal stability of polyamide.
2Ease of operation
If the amount of polydiorganosiloxane soft segments is increased to improve flexibility and elastomeric properties, then the tensile strength and thermal stability decrease
Solution Approach 1:
The patent applies local quality by concentrating the hard polyamide segments at specific locations within the polymer chain to provide localized reinforcement. This allows the majority of the polymer to maintain soft siloxane segments for flexibility while discrete hard segments provide tensile strength and thermal stability.
Solution Approach 2:
By segmenting the polymer into distinct soft and hard blocks, the patent allows optimization of each segment's properties. The soft segments can be maximized for flexibility while the hard segments are minimized but strategically placed to provide necessary strength, achieving a balance between flexibility and tensile strength.
3Strength
If polydiorganosiloxane polyureas are used to improve tensile strength, then the copolymers degrade when subjected to elevated temperatures such as 250° C. or higher
Solution Approach 1:
The patent changes the chemical composition parameter by replacing polyurea hard segments with polyoxamide hard segments. This parameter change results in a material that maintains tensile strength while achieving thermal stability up to 250° C. or higher, as the polyoxamide linkage is more thermally stable than the polyurea linkage.
4Ease of manufacture
If known polydiorganosiloxane polyoxamide copolymers are made by mixing diamine with precursor including polydiorganosiloxane segment and oxalylamino groups, then the copolymers can be formed, but the distribution and level of hard segments cannot be controlled
Solution Approach 1:
The patent employs preliminary action by first forming a polyol from the polydiorganosiloxane diamine and oxalate ester, then subsequently reacting this polyol with additional diamine. This two-step preliminary action allows precise control over the hard segment distribution and level, as the first step establishes the soft segment framework and the second step introduces hard segments at controlled positions.
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 resulting copolymers exhibit improved solvent resistance, heat stability, and optical clarity, with some being insoluble in solvents like toluene and tetrahydrofuran, and maintaining structural integrity up to high temperatures, making them suitable for various applications including adhesive compositions and films.
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.
Implementation Method 2
Because polydiorganosiloxanes (e.g., polydimethylsiloxanes) and polyamides often have significantly different solubility parameters, it can be difficult to find reaction conditions for production of siloxane-based polyamides that result in high degrees of polymerization
Data Source
AI summary
Silicone polyoxamide and silicone polyoxamide-hydrazide copolymers 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 1500; each p is independently an integer of 1 to 10, and the average of p is 1.2 or greater; and each q is independently an integer of 1 or greater, and every q is not the same integer.