Photocurable Polymer Compositions for High-Temperature 3D Printing
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Solution Overview
Problem
Existing lithographic processes for 3D printing with high-performance polymers face challenges in achieving high thermal stability and mechanical properties at elevated temperatures, particularly above 150°C, due to the need for materials to remain thermally stable while avoiding thermal polymerization of photo-polymerizable functional groups.
Innovation Solution
A polymer formulation comprising poly(aryl ether sulfone) (PAES) with photo-polymerizable terminal groups and a polyfunctional cross-linker, which can be cured at temperatures below or above the glass transition temperature of the polymer, resulting in high thermal and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high performance polymers are used in lithographic processes, then mechanical properties and thermal stability are improved, but the material becomes difficult to process due to thermal polymerization risks and requires heating above Tg or Tm
Solution Approach 1:
The patent changes the physical state parameter of the polymer from solid to liquid by heating above Tg or Tm, enabling lithographic processing. It also modifies the chemical structure by introducing photo-polymerizable functional groups that allow curing at lower temperatures, thus resolving the contradiction between thermal stability and processability
Solution Approach 2:
The patent introduces a photoinitiator as an intermediary substance that absorbs UV light and generates reactive species to trigger polymerization. This mediator enables the curing process to proceed at lower temperatures without requiring the polymer to remain in a liquid state throughout the entire process, thus improving processability while maintaining thermal stability
2Ease of operation
If polymerizable formulations are heated above Tg or Tm to remain liquid, then ease of printing is improved, but thermal stability at elevated temperatures deteriorates
Solution Approach 1:
The patent performs preliminary heating to melt the polymer above Tg or Tm before printing, enabling easy processing. Then, during or after printing, UV irradiation triggers rapid cross-linking to form a thermally stable network structure, thus achieving both ease of operation and thermal stability through sequential actions
Solution Approach 2:
The patent creates a composite system combining the base polymer with photo-polymerizable functional groups and cross-linkers. This composite formulation allows the material to exhibit liquid behavior during printing (due to the polymer matrix) while forming a thermally stable cross-linked network upon curing, thus resolving the contradiction between processing ease and thermal stability
3Ease of manufacture
If photo-polymerizable functional groups are added to polymers, then lithographic processability is improved, but thermal polymerization of these groups occurs at high temperatures
Solution Approach 1:
The patent replaces thermal energy (heat) with optical energy (UV light) as the activation mechanism for polymerization. By using photoinitiators that absorb UV light to generate reactive species, the system substitutes the thermal field with an optical field, enabling functional group activation at lower temperatures and avoiding thermal polymerization while maintaining lithographic processability
Solution Approach 2:
The patent changes the activation parameter from thermal (temperature) to optical (UV light wavelength). By selecting photoinitiators with appropriate absorption spectra and using UV irradiation, the system activates photo-polymerizable groups at temperatures well below the polymer's Tg or Tm, thus avoiding thermal polymerization while achieving successful lithographic curing
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 formulation enables the production of 3D printed parts with high thermal stability and mechanical properties, suitable for applications requiring durability at elevated temperatures.
Implementation Method 1
Lithographic processes generally use polymerizable formulations that are liquid in order to obtain parts with a good resolution. Polymerizable formulations that are liquid at room temperature are easier to use in a printing process... They also need to possess functional groups that are photo-polymerizable or cross-linkable, that-is-to-say reactive during the printing process when irradiating the layer of polymerizable formulation.
Implementation Method 2
the formulation comprising a functionalized polymer and a cross-linker... a polyfunctional photo-crosslinker, which creates a high molecular weight network with polymer (P) after printing and curing
Data Source
AI summary
The present invention relates to relates to a polymer formulation for three- dimensionally (3D) printing an article by stereolithography, the formulation comprising a functionalized polymer. The invention further relates to lithographic methods to form 3D objects that incorporate the aforementioned polymer formulation.