Straining Flow Spinning for Spider Silk-Like Fiber Production
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Solution Overview
Problem
Current methods for producing artificial silk fibers, such as wet spinning and electrospinning, fail to effectively control the stresses exerted on the dope solution, leading to fibers with inferior mechanical properties compared to natural spider silk.
Innovation Solution
The straining flow spinning (SFS) process, which involves extruding a dope solution through a capillary into a focusing fluid, allowing for controlled stress application and molecular self-assembly to form fibers, mimicking the natural spinning mechanism of spider silk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wet spinning or electrospinning is used to produce artificial silk fibers, then fiber production is achieved, but the mechanical properties (tensile strength and work to fracture) are inferior compared to natural spider silk
Solution Approach 1:
A co-flow fluid is introduced as an intermediary substance between the dope solution and the spinning environment. This co-flow acts as a mediator that applies controlled extensional stresses to the dope jet, enabling proper molecular alignment and fiber formation. The co-flow fluid transfers mechanical stress from the spinning system to the polymer chains in a controlled manner, resolving the contradiction between achieving natural silk-like mechanical properties and maintaining ease of manufacture.
Solution Approach 2:
The invention changes the physical parameters of the spinning process by introducing a co-flow fluid with specific flow rates and velocities. By adjusting the co-flow rate and its velocity profile, controlled extensional stresses are applied to the dope solution during spinning. This parameter change enables the dope molecules to align properly and form fibers with mechanical properties comparable to natural spider silk, while maintaining a relatively simple manufacturing process.
2Strength
If high stresses are applied to the dope solution during spinning, then fiber strength is improved, but control over the stress application becomes difficult
Solution Approach 1:
The co-flow fluid serves as an intermediary that distributes and controls stress application throughout the dope jet. Rather than applying concentrated or uncontrolled stress, the co-flow acts as a mediator that evenly distributes extensional stresses across the entire dope stream. This intermediary approach enables precise control over stress magnitude and distribution, allowing high stresses to be applied uniformly to achieve strong fibers while maintaining manufacturing precision.
Solution Approach 2:
The invention uses fluid dynamics (hydraulics) to control stress application. By adjusting the flow rate, velocity, and pressure of the co-flow fluid, precise control over the extensional stresses applied to the dope solution is achieved. The hydraulic system enables continuous and adjustable stress control, allowing optimization of fiber strength while maintaining precise manufacturing control through flow rate regulation.
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 process enables the production of fibers with mechanical properties comparable to natural spider silk, including high tensile strength and work to fracture, while maintaining biocompatibility and immune response minimization.
Implementation Method 1
The interaction of the dope with the focusing fluid results in selectively extracting solvent from the doping solution, which solvent is extracted into the surrounding environment of the focusing fluid
Implementation Method 2
The straining flow between the inner dope solution and outer focusing fluid, to which the name of the process refers
Data Source
AI summary
A method of molecular self-assembly is disclosed using two interacting streams that are allowed to interact and are subsequently forced through an orifice. A first stream of a dope solution of polymer molecules is extruded out of a capillary. The dope stream is surrounded by a focusing fluid which is miscible with the dope solution. The interaction between the jet of dope solution and surrounding focusing fluid creates hydrodynamic stretching and allows for extracting solvent from the dope solution. Concentrated polymers within the solution at stretched regions of the jet interact, and finally self-assembly takes place after the fluids are forced through the outlet of a converging nozzle. The formation of the structure can be optionally completed in a coagulating space. The structures thus obtained such as fibers or threads can be wound onto a mandrel.