Siloxane Elastomer Curing via Radical Initiators
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Solution Overview
Problem
Current methods for forming silicone elastomers using hydrosilylation reactions are slow, requiring significant heat and time, making them unsuitable for additive manufacturing and photocuring processes like stereolithography, which necessitates a composition that can cure quickly without added heat.
Innovation Solution
A composition comprising a siloxane monomer with silane functional groups, a hydrosilylation catalyst, and a radical initiator, which can be used in additive manufacturing to form three-dimensional structures, either thermally or photo-cured, allowing for faster curing kinetics and control over the network structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a radical initiator and photosensitizing agent are added to convert thermal-curable siloxane resin to radiation-curable siloxane resin, then curing speed is improved and curing time is reduced, but composition complexity increases
Solution Approach 1:
A photosensitizing agent is introduced as an intermediary substance that absorbs radiation energy and transfers it to the radical initiator, enabling the curing process to be initiated by radiation rather than heat. This mediator allows the conversion from thermal-curable to radiation-curable siloxane resin, achieving faster curing speeds while maintaining composition manageability through the use of a well-defined photosensitizing mechanism.
2Loss of time
If significant heat is applied to cure silicone elastomer using radical-formation reaction process, then curing is achieved in reasonable time duration, but energy consumption increases and applicability to photocuring processes is limited
Solution Approach 1:
The thermal curing mechanism is replaced with a radiation-initiated radical formation process. Instead of using heat (thermal energy) to initiate and sustain the curing reaction, radiation energy is absorbed by the photosensitizing agent and transferred to the radical initiator, which then generates radicals to drive the crosslinking reaction. This substitution eliminates the need for significant heat input while achieving comparable or faster curing times, reducing energy consumption and enabling photocuring applications.
3Strength
If conventional hydrosilylation reaction is used to form crosslinked elastomer, then mechanical properties can be tuned, but curing time is excessively long and added heat is required
Solution Approach 1:
The curing mechanism parameters are fundamentally changed by introducing a radical initiator and photosensitizing agent system. This changes the reaction pathway from conventional thermal hydrosilylation to radiation-initiated radical crosslinking. The parameter change enables the curing process to proceed much faster at lower temperatures, reducing curing time from hours to minutes or seconds, while still achieving tunable mechanical properties through control of the crosslinking reaction and composition formulation.
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
This approach enables the rapid formation of silicone elastomers suitable for additive manufacturing, reducing curing time and allowing for the creation of complex geometries, enhancing the efficiency and applicability of silicone materials in various applications.
Implementation Method 1
a radical initiator
Implementation Method 2
Hydrosilylation of vinyl-terminated polysiloxanes is an important reaction mechanism for the preparation of organosilicon compounds
Implementation Method 3
a curing accelerator for converting a thermal-curable siloxane resin to a radiation-curable siloxane resin includes a radical initiator and a photosensitizing agent
Data Source
AI summary
A composition for forming a siloxane elastomer material includes a siloxane monomer having at least one silane functional group, a hydrosilylation catalyst, and a radical initiator. A curing accelerator for converting a thermal-curable siloxane resin to a radiation-curable siloxane resin includes a radical initiator and a photosensitizing agent.