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 specific repeating units, allowing for the incorporation of extra hard segments and varying the ratio of soft to hard segments, which are synthesized through a method involving reaction of a compound with a diamine and an oxalate ester to form amine-terminated polymers, enabling improved mechanical properties and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alternating soft and hard segment polydiorganosiloxane polyoxamide copolymers are used, then thermal stability is improved, but the ability to control the level and distribution of hard segments is limited
Solution Approach 1:
The copolymer is divided into distinct soft segments (polydiorganosiloxane) and hard segments (oxamide), allowing independent control of each segment's properties and distribution. This segmentation enables the hard segments to be strategically positioned within the polymer chain to optimize both thermal stability and mechanical properties.
Solution Approach 2:
The patent introduces runs of hard segments with varying lengths distributed throughout the polymer chain, creating local regions with different properties. This local quality variation allows control over hard segment concentration in specific areas, enhancing both thermal resistance and mechanical strength while maintaining processability.
2Ease of manufacture
If polydiorganosiloxane polyamides are prepared by condensation reactions, then copolymers can be formed, but it is difficult to achieve high degrees of polymerization due to different solubility parameters
Solution Approach 1:
The patent modifies reaction parameters including using specific catalysts, controlling temperature profiles, and adjusting solvent systems to achieve high degrees of polymerization despite the solubility parameter differences between polydiorganosiloxane and polyamide segments. These parameter changes enable effective condensation reactions while maintaining polymer chain growth.
3Adaptability or versatility
If polydiorganosiloxane polyureas are used, then desirable characteristics are achieved, but degradation occurs at elevated temperatures of 250°C or higher
Solution Approach 1:
The patent changes the chemical structure of the hard segment from polyurea to polyoxamide, which has higher thermal stability. This parameter change in the chemical composition allows the material to maintain its desirable characteristics while resisting degradation at temperatures of 250°C or higher.
Solution Approach 2:
The patent creates a composite structure combining polydiorganosiloxane soft segments with polyoxamide hard segments. This composite approach integrates the flexibility and processability of siloxane with the thermal stability of oxamide, achieving both desirable characteristics and high temperature resistance.
4Ease of manufacture
If polydiorganosiloxane segments are kept short to improve solubility, then reaction conditions are easier to achieve, but tensile strength is reduced
Solution Approach 1:
The patent uses short polydiorganosiloxane segments that are segmented and distributed throughout the chain rather than using one long segment. This segmentation maintains solubility and ease of manufacturing while the cumulative effect of multiple segments contributes to tensile strength through the hard segment crosslinks.
Solution Approach 2:
The patent compensates for the reduced tensile strength from short siloxane segments by incorporating robust polyoxamide hard segments that form strong intermolecular bonds. This composite structure balances the solubility benefits of short segments with the strength provided by the hard segment network.
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 enhanced solvent resistance, heat stability, and improved mechanical properties, including increased hardness and modulus, while maintaining optical clarity and low refractive index, making them suitable for various applications including adhesives and coatings.
Implementation Method 1
The siloxane polymers have unique properties derived mainly from the physical and chemical characteristics of the siloxane bond. These properties include low glass transition temperature, thermal and oxidative stability, resistance to ultraviolet radiation, low surface energy and hydrophobicity
Implementation Method 2
Such polydiorganosiloxane polyoxamide copolymers can usually be subjected to elevated temperatures up to 250°C or higher without apparent degradation
Implementation Method 3
maintaining optical clarity and low refractive index
Data Source
AI summary
A copolymer comprises at least two repeating units of formula I: In 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 to 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 each q is independently an integer of 1 or greater, and wherein at least 50% of the q's are the integer 2.