Polysiloxane-polycarbonate Copolymer Heat Resistance
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Solution Overview
Problem
Polysiloxane-polycarbonate copolymers exhibit poor heat resistance, impact resistance at high temperatures, and transparency issues, limiting their use as optical and exterior materials, and mixing with other polymers to improve abrasion resistance compromises other properties.
Innovation Solution
A hydroxy-terminated siloxane with ester or urethane linkages is used as a repeating unit in a polysiloxane-polycarbonate copolymer, combined with a polycarbonate block through an interfacial reaction and polymerization process, to enhance mechanical properties and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polysiloxane-polycarbonate copolymer is used to improve impact resistance at low temperature, then impact resistance is improved, but heat resistance and transparency deteriorate
Solution Approach 1:
The patent changes the chemical structure parameters of the copolymer by introducing specific siloxane units with particular molecular weights and compositions. By controlling the siloxane content (5-30 mass%) and using specific hydroxy-terminated siloxane structures, the material achieves improved impact resistance while maintaining heat resistance through optimized molecular architecture rather than simple blending.
Solution Approach 2:
The patent creates a composite copolymer structure combining polycarbonate and polysiloxane segments at the molecular level. This composite approach allows the material to exhibit both the high impact resistance of polysiloxane and the heat resistance of polycarbonate simultaneously, resolving the contradiction between these two properties.
2Strength
If polysiloxane-polycarbonate copolymer is used to improve impact resistance at low temperature, then impact resistance is improved, but transparency deteriorates
Solution Approach 1:
The patent optimizes optical parameters by controlling the siloxane unit structure and distribution. By using specific hydroxy-terminated siloxane structures and controlling the siloxane content within 5-30 mass%, the material achieves high impact resistance while maintaining excellent transparency and low haze values through refined molecular architecture.
3Strength
If another polymer is mixed with polysiloxane-polycarbonate copolymer to improve abrasion resistance, then abrasion resistance is improved, but transparency and other properties deteriorate
Solution Approach 1:
Instead of mixing separate polymers, the patent creates an integrated copolymer composite where siloxane and polycarbonate segments are combined at the molecular level. This molecular-level composite structure provides abrasion resistance through the siloxane components while maintaining the transparency and other properties of the polycarbonate matrix, avoiding the degradation caused by macroscopic blending.
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 copolymer achieves excellent heat resistance, impact resistance at low temperatures, and abrasion resistance while maintaining transparency, suitable for applications like helmets and automobile parts.
Implementation Method 1
a step of reacting the above hydroxy-terminated siloxane having ester linkage or urethane linkage and an oligomeric polycarbonate under an interfacial reaction condition to form a polysiloxane-polycarbonate intermediate
Implementation Method 2
a step of polymerizing said intermediate by using a first polymerization catalyst
Data Source
AI summary
Provided are a hydroxy-terminated siloxane, a polysiloxane-polycarbonate copolymer including same as a repeating unit, and a preparation method thereof. The hydroxyl-terminated siloxane has the structure of chemical formula 1.