Reversible Polyester Bonding Coating for High-Strength Reassembly
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Solution Overview
Problem
Current space frame construction technologies face challenges with weight, reassembly, and temperature stability, as well as the need for scalable and fully reversible adhesive systems suitable for space missions, which existing solutions fail to address effectively.
Innovation Solution
The development of a reversible adhesive system using interchain transesterification (ITR) between aromatic thermosetting copolyester (ATSP) coatings, which allows for cohesive failure and repeated bonding cycles across a wide temperature range, utilizing electrostatic powder deposition and heat to create a thermoset network with exchangeable ester bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal-based unit elements are permanently joined, then structural strength is improved, but reassembly capability deteriorates and weight increases
Solution Approach 1:
The patent employs dynamic covalent bonds (transesterification reactions) that can reversibly form and break under controlled conditions. The ester bonds in the ATSP adhesive remain stable during bonding but can be cleaved by moisture or enzymatic action to enable disassembly, providing dynamic reconfigurability while maintaining structural integrity during operation
Solution Approach 2:
The patent changes the chemical state of the adhesive bonds through controlled hydrolysis or enzymatic degradation. By altering environmental parameters (moisture content, pH, temperature) the bonds transition from stable to labile states, enabling reversible assembly-disassembly cycles while maintaining strength during the bonded state
2Adaptability or versatility
If reversible adhesive systems are used, then reassembly capability is improved, but bonding strength deteriorates
Solution Approach 1:
The patent uses aromatic thermosetting polyester (ATSP) adhesives that combine thermoset network stability with reversible ester bond chemistry. The composite structure incorporates both strong covalent crosslinks for strength and hydrolytically labile ester bonds for reversibility, achieving high bonding strength (comparable to metal joints) while maintaining reversibility
Solution Approach 2:
The patent introduces water or enzymes as intermediary agents that mediate the reversible bonding process. These intermediaries trigger bond cleavage without compromising the fundamental strength of the adhesive system, allowing controlled disassembly while preserving the bonding capability for reassembly
3Ease of operation
If uncured polymer or meltable interstitial phase is used, then adhesive flexibility is improved, but vapor pressure in vacuum deteriorates
Solution Approach 1:
The patent avoids phase transitions (melting, vaporization) by using a fully cured thermoset adhesive system. The ATSP adhesive cures to form a crosslinked network that remains in the solid state across the full temperature range, eliminating vapor pressure issues in vacuum while maintaining mechanical flexibility through the polymer network structure
Solution Approach 2:
The patent creates a chemically inert, crosslinked thermoset environment that is stable in vacuum conditions. The cured ATSP adhesive forms a dense, non-volatile network that does not outgas or decompose in the vacuum environment, providing both flexibility and vacuum compatibility
4Adaptability or versatility
If gecko adhesive schemes are used, then reversible bonding is improved, but scalability to complex geometries deteriorates
Solution Approach 1:
The patent extracts the complex surface patterning requirement from the adhesive system. Instead of requiring microstructured surfaces (gecko-inspired patterns), the ATSP adhesive achieves reversible bonding through its chemical composition and bonding mechanism, allowing application on smooth, complex geometries without surface texturing
Solution Approach 2:
The patent replaces the mechanical interlocking mechanism of gecko adhesives (requiring fibrillar surface structures) with a chemical bonding mechanism based on transesterification reactions. This substitution eliminates the need for complex surface patterning while maintaining reversible bonding capability across diverse geometries
5Adaptability or versatility
If polymers with glass transitions below 120°C are used, then adhesive reversibility is improved, but temperature stability deteriorates
Solution Approach 1:
The patent changes the glass transition temperature parameter of the adhesive polymer to above 120°C (specifically 170-310°C for ATSP). This parameter change allows the adhesive to maintain its rubbery, flexible state and reversibility while being thermally stable across the space temperature range, avoiding uncontrolled phase transitions
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 solution provides a high-strength, fully reversible adhesive capable of multiple cycles without delamination, maintaining mechanical properties across extreme temperatures, thus addressing the limitations of existing technologies in space applications.
Implementation Method 1
interchain transesterifications (ITR—a type of dynamic covalent exchange reactions afforded by aromatic thermosetting copolyesters (ATSP)) between two ATSP coatings
Implementation Method 2
depositing the crosslinkable resin by electrostatic powder deposition onto substrates
Implementation Method 3
bonding the crosslinkable resin coated portions of the substrates by abutting the crosslinkable resin coated portions of the substrates to each other and applying a compressive pressure in the range 100 kPa to 2 MPa at an elevated temperature in the range of 150° C. to 420° C. such that the crosslinkable resin coated portions of the substrates' crosslinks with itself
Data Source
AI summary
A method of reversible bonding based on deposition of a coating capable of an indefinite number of reversible bonding cycles as enable by bond exchange reactions is provided. This is accomplished by deposition of crosslinkable aromatic polyester oligomers on a substrate. The coated article is heated to produce a fully thermoset network by condensation reactions. The fully thermoset network has access to a type of bond exchange reaction within the resin that permits the dynamic exchange of ester bonds within the resin. To execute the bonding step a source of heat is applied at a pressure. To debond, there is applied force in tension and/or shear that causes the coating to fail. The reversibility of the process is contingent on the cohesive (rather than adhesive) failure of the coating—that is, the coating must not delaminate from the substrate. Failure must occur in the resin of the reversible coating.