3D Printing Vinyl Shape Memory Polymers Without Photoblockers
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Solution Overview
Problem
Existing 3D printing methods for vinyl-functionalized and shape memory polymers face challenges in maintaining mechanical integrity, achieving complex geometries, controlling degradation rates, and ensuring biocompatibility, particularly for biomedical applications, due to issues with photocrosslinking, solubility, and the need for photoblockers.
Innovation Solution
A 3D printing process using precursor solutions with vinyl-terminated side-chains and acrylate crosslinkers, free from photoblockers, that allow for layer-by-layer photo-polymerization, enabling the production of articles with tunable thermal, mechanical, and degradation properties, including porous structures without the use of photoabsorbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dip casting is used to manufacture biomedical devices, then manufacturing speed is improved, but thickness consistency and intricate detail generation deteriorate
Solution Approach 1:
The patent replaces the mechanical dip casting process with a photocuring-based additive manufacturing process. The precursor solution is deposited and then cured using light exposure, eliminating gravitational effects that cause thickness variations in dip casting. This allows for precise control of layer thickness and consistent manufacturing while maintaining rapid production capability.
2Shape
If salt leaching is used to create pores, then pore generation is achieved, but precision and consistency deteriorate
Solution Approach 1:
The patent incorporates photoblocker particles directly into the precursor solution before deposition. These particles are strategically placed in regions where pores should form, and during photocuring, they prevent crosslinking in those specific areas. This preliminary placement of photoblockers enables precise and consistent pore generation without requiring post-processing leaching steps.
3Shape
If laser ablation is used to create intricate details, then complex geometries are achieved, but cost and toxic residual removal deteriorate
Solution Approach 1:
The patent replaces laser ablation with a photocuring process using photoblocker particles. Instead of removing material through high-energy laser ablation (which creates toxic residues), the process uses light-induced crosslinking inhibition to create complex geometries and intricate details. This substitution eliminates toxic residuals while maintaining the ability to generate complex shapes and features.
4Productivity
If injection molding is used for photocured materials, then manufacturing efficiency is improved, but mold complexity and removal difficulty deteriorate
Solution Approach 1:
The patent replaces injection molding with a direct photocuring additive manufacturing process. The precursor solution is deposited layer-by-layer and cured in situ using light exposure, eliminating the need for complex molds. This approach maintains manufacturing efficiency while completely avoiding mold complexity and removal difficulties associated with injection molding of photocured materials.
5Stability of the object's composition
If photoblockers are added to prevent crosslinking in pores, then crosslinking control is improved, but biocompatibility and formulation complexity deteriorate
Solution Approach 1:
The patent uses biocompatible photoblocker particles such as titanium dioxide or zinc oxide, which are safe for biomedical applications. By carefully controlling the concentration, size, and optical properties of these photoblockers, the process achieves precise crosslinking control in porous regions while maintaining excellent biocompatibility. The formulation complexity is managed through systematic selection of photoblocker types and concentrations optimized for specific application requirements.
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 process enables the production of biocompatible, mechanically stable, and customizable articles with complex geometries and controlled degradation rates, suitable for biomedical applications, without the need for toxic photoblockers, simplifying manufacturing and enhancing biocompatibility.
Implementation Method 1
exposing a precursor solution to an intensity and frequency of light to initiate photo-polymerization of the precursor solution to form a layer of the article
Data Source
AI summary
Various precursor solutions and methods of 3D printing and other additive manufacturing approaches are provided for the manufacture of articles using photocrosslinkable vinyl shape memory polymers. In various aspects, articles are manufactured by a process comprising (i) exposing a precursor solution to an intensity and frequency of light to initiate photo-polymerization of the precursor solution to form a layer of the article; and (ii) repeating step (i) a number of times to form the article in a layer-by-layer approach; wherein the precursor solution comprises a first polymeric precursor comprising a plurality of vinyl terminated side-chains attached thereto. A vinyl-functionalized, photocrosslinkable SMP used as an example herein is a novel variant of a previously disclosed SMP composition, with higher amounts of vinyl functionalization but similar thermomechanical properties to the SMP library previously disclosed. Moreover, a unique combination of chemistries is disclosed that incorporates the aforementioned vinyl-functionalized SMPs along with acrylate-based crosslinkers. Additional novel compositions are disclosed containing the vinyl-functionalized SMPs with additional dithiol functionalizations, vinyl-functionalized SMPs with dithiol crosslinkers, as well as vinyl-functionalized SMPs with both acrylate-based and dithiol crosslinkers, as another means to tune degradation rates and other material properties. The articles can include a variety of articles such as stents, grafts, external sheaths, and the like. Beneficially, the printed articles can include a plurality of pores having an average diameter of about 50 μm to about 5000 μm, about 500 μm to about 2000 μm, or about 1000 μm even in the absence of a photoblocker.