3D Printed Silicone Double Networks for Complex Geometries
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Solution Overview
Problem
Current 3D printing technologies face challenges in achieving ideal elastomeric performance for silicone materials, particularly in creating complex structures and bonding between soft and stiff printed silicones, due to limitations in gelation kinetics, rheological properties, and mechanical robustness, which hinder the production of high aspect ratio features and mechanical gradients.
Innovation Solution
A polymer composition forming an interpenetrating polymer network (IPN) is developed, comprising a photocurable siloxane polymer with unsaturated carbon-carbon bonds and a condensation-curable siloxane polymer, where the first network provides shape fixity and processability during printing, and the second network offers mechanical robustness, enabling the creation of complex geometries and mechanical gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a viscous matrix is used to embed ink for kinetically trapping commercial resins, then the potential to print designs of greater complexity is achieved, but path planning becomes complicated and the trade-off in resolution and print speed remains unsolved
Solution Approach 1:
The patent changes the chemical parameters of the silicone system by using free-radical initiated photopolymerization instead of conventional hydrosilylation or condensation mechanisms. This allows the material to maintain low viscosity during printing while achieving rapid gelation and curing, thereby simplifying path planning and improving print speed without sacrificing design complexity
2Productivity
If free-radical initiated photopolymerization of unsaturated carbon bonds is used in custom formulations of polysiloxanes, then the processing requirements of stereolithography are met, but the desirable mechanical properties inherent to RTV silicones are not demonstrated
Solution Approach 1:
The patent creates a composite polymer system that combines the benefits of free-radical photopolymerization (rapid curing, low viscosity) with the mechanical properties of RTV silicones. The custom formulation of polysiloxanes with unsaturated carbon bonds achieves both rapid gelation for high-speed printing and the desirable mechanical properties including elasticity and toughness characteristic of RTV silicones
3Strength
If conventional crosslinking mechanisms (hydrosilylation or condensation) are used for RTV silicones, then impressive elastomeric properties and chemical resistance are achieved, but gelation kinetics and rheological properties limit print fidelity for high aspect ratio structures and overhanging features
Solution Approach 1:
The patent replaces the conventional chemical crosslinking mechanisms (hydrosilylation or condensation) with free-radical initiated photopolymerization. This substitution fundamentally changes the gelation kinetics and rheological properties, allowing the material to maintain low viscosity during deposition while achieving rapid gelation that prevents wetting, slumping, or bleeding, thereby achieving high print fidelity for complex structures while maintaining elastomeric properties
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 IPN composition allows for the production of 3D printed parts with enhanced mechanical properties, including toughness and elongation, while maintaining low viscosity for improved printability and bonding between soft and stiff materials, overcoming the limitations of existing technologies.
Implementation Method 1
the first base component is configured to polymerize into a primary polymer network... the first base component includes a siloxane polymer including a plurality of functional groups with unsaturated carbon-carbon bonds... exposed to actinic radiation
Implementation Method 2
the second base component is configured to polymerize into a secondary polymer network... the second base component is condensation curable... a catalyst
Implementation Method 3
the primary and secondary polymer networks together form an interpenetrating polymer network... two distinct percolated networks of polymers homogeneously occupying the same volume
Data Source
AI summary
A polymer composition that includes a blended resin having a viscosity below 10 pascal-seconds before exposure to actinic radiation is provided. The blended resin includes a first base component that is photocurable, and the first base component includes (i) a first siloxane polymer including a plurality of thiol groups and (ii) a second siloxane polymer including a plurality of functional groups with unsaturated carbon-carbon bond. The blended resin also includes a photoinitiator, a second base component that is condensation curable, and a catalyst. The first base component is configured to polymerize into a primary polymer network and the second base component is configured to polymerize into a secondary polymer network. Furthermore, the primary and secondary polymer networks together form an interpenetrating polymer network.