Polymer Strand Pulling by Viscoelastic Dip-Coating
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Solution Overview
Problem
Existing methods for producing polymer strands, such as electrospinning and wet extrusion, face challenges in maintaining biomolecule integrity, require specialized equipment, and are limited in throughput and ability to incorporate additives, leading to damaged biomolecules and slow production rates.
Innovation Solution
A process involving a nucleation element is used to pull polymer strands from a pre-strand composition at a rate less than the reptation time, inducing a viscoelastic response, allowing for the production of strands with controlled diameter and length, and enabling the incorporation of bioactive molecules using simpler equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If electrospinning is used to produce strands with collagen, then strand length scales similar to native collagen are achieved, but volatile solvents denature the collagen and high shear stresses damage the collagen molecules
Solution Approach 1:
The patent changes the physical parameters of the process by using a dip-coating method with controlled withdrawal speed instead of electrospinning parameters. The withdrawal speed is specifically controlled to be less than the reptation time of polymer entanglements, creating a viscoelastic response that allows strand formation without the harmful high shear stresses and volatile solvents of electrospinning, thus preserving collagen integrity while achieving native-like strand lengths
Solution Approach 2:
The patent replaces the electrospinning mechanical system (which uses high voltage electric fields and rapid solvent evaporation) with a dip-coating mechanical system that uses controlled withdrawal motion through a polymer solution. This substitution eliminates the need for volatile solvents and high shear stresses, thereby preventing collagen denaturation and molecular damage while still producing strands at length scales similar to native collagen
2Object-affected harmful factors
If wet extrusion is used to produce self-assembling collagen strands, then high shear rates and volatile solvents are avoided, but production rate becomes extremely slow and only single thick strands are produced
Solution Approach 1:
The patent applies segmentation by using a multi-pronged dip-coating apparatus where multiple prongs simultaneously produce multiple strands from a single polymer solution bath. This divides the single-thread production of traditional wet extrusion into parallel multi-strand production, dramatically increasing throughput while maintaining the gentle processing conditions that preserve collagen integrity
Solution Approach 2:
The dip-coating apparatus serves multiple functions simultaneously: it produces multiple strands in parallel, controls strand diameter through prong geometry, and maintains biomolecule integrity through gentle processing. This multi-functionality overcomes the limitation of wet extrusion which produces only single thick strands at extremely slow rates
3Productivity
If electrospinning or wet spinning processes are used, then strands can be produced, but ability to incorporate macromolecules, supramolecular assemblies and nano/micro particulates is limited due to clogging of small gauge nozzles
Solution Approach 1:
The patent extracts the strand formation process from the constrained environment of small gauge nozzles and replaces it with an open dip-coating geometry. This removes the clogging limitation entirely, allowing free incorporation of macromolecules, supramolecular assemblies, and nano/micro particulates into the strands without restricting the types of additives that can be used
4Productivity
If specialized equipment is used for electrospinning, then strand production is achieved, but equipment complexity increases and automation becomes difficult
Solution Approach 1:
The patent replaces complex, expensive, specialized electrospinning equipment with simple, inexpensive dip-coating apparatus that can be easily fabricated and modified. The simple geometry of the dip-coating setup makes it inherently more amenable to automation and scaling, eliminating the need for highly specialized equipment while maintaining strand production capability
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 achieves faster production rates, maintains biomolecule activity, and allows for the production of strands with desired lengths and diameters, suitable for large-scale manufacturing and various applications.
Implementation Method 1
withdrawing the nucleation element from the pre-strand composition so that a strand comprising the polymer is pulled by the nucleation element from the pre-strand composition, the nucleation element being withdrawn at a rate such that a pull time (τpull) of the nucleation element is less than a reptation time (τrep) required to relax polymer entanglements in the pre-strand composition, thereby inducing a viscoelastic response in the pre-strand composition
Data Source
AI summary
A process for producing a polymer strand involves: inserting a nucleation element into a pre-strand composition, the pre-strand composition comprising a polymer mixed with a solvent, the polymer having a concentration in the pre-strand composition that is greater than or equal to an overlap concentration (c*) of the polymer in the pre-strand composition; and, withdrawing the nucleation element from the pre-strand composition so that a strand comprising the polymer is pulled by the nucleation element from the pre-strand composition, the nucleation element being withdrawn at a rate such that a pull time (τpull) of the nucleation element is less than reptation time (τrep) required to relax polymer entanglements in the pre-strand composition, thereby inducing a viscoelastic response in the pre-strand composition as the strand is pulled by the nucleation element from the pre-strand composition.