Non-volatile Thermotropic Optical Switches Using Ionic Liquid Blends
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Solution Overview
Problem
Conventional thermotropic materials for smart windows face limitations such as restricted operation temperature, high demands on sealing efficiency, volume reduction, and poor optical switching characteristics, which hinder their effectiveness in modulating light transmission under external temperature stimuli.
Innovation Solution
A non-volatile thermotropic composite material comprising a non-aqueous proton donating material, a proton accepting material with hydrogen bonding ability, and a non-volatile polymeric matrix, configured to reversibly change optical states based on thermal energy, enabling transparent-to-opaque transitions without water or organic solvents, and maintaining stability across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermotropic materials are used for smart windows, then optical switching characteristics are achieved, but volume reduction and water evaporation occur leading to poor stability
Solution Approach 1:
The patent employs a composite material system consisting of a thermotropic polymer blend (PNIPAm-PVAc in various ratios) embedded within a porous matrix material. This composite structure prevents volume reduction and water evaporation by providing a stable framework that maintains the polymer blend's integrity during phase transitions, thereby achieving both optical switching functionality and long-term stability.
Solution Approach 2:
The patent utilizes a porous matrix (such as porous polyethylene terephthalate or porous alumina) to house the thermotropic polymer blend. The porous structure provides mechanical support while allowing the polymer to undergo volume changes during thermotropic transitions without collapsing or evaporating, thus maintaining both optical performance and structural stability over time.
2Adaptability or versatility
If conventional thermotropic materials are used, then phase separation mechanism provides good optical switching, but operation temperature range is restricted
Solution Approach 1:
The patent modifies the thermotropic properties by adjusting the compositional parameters of the polymer blend (varying PNIPAm-PVAc ratios) and the pore size of the matrix material. These parameter changes allow tuning of the phase separation temperature to match different operational requirements, expanding the adaptable temperature range while maintaining effective optical switching characteristics.
Solution Approach 2:
The patent creates local environmental differences within the composite structure by using a porous matrix with specific pore sizes and distributions. This local structural quality modification allows different regions of the material to operate at slightly different temperatures, effectively broadening the overall operational temperature range while preserving the phase separation mechanism's optical switching capability.
3Speed
If conventional thermotropic materials are used, then rapid switching is achieved, but sealing efficiency demands are high
Solution Approach 1:
The porous matrix acts as an intermediary structure between the thermotropic polymer blend and the external environment. It provides mechanical containment and structural support, reducing the sealing demands on the overall device while allowing the polymer to perform rapid switching through its intrinsic phase separation mechanism. The matrix mediates between the need for fast response and the need for reliable sealing.
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 composite material achieves stable and efficient light modulation across a broad temperature range, reducing energy consumption by autonomously controlling solar irradiation and thermal comfort, while avoiding the drawbacks of conventional thermotropic materials.
Implementation Method 1
a second component comprising a monomer, an oligomer or a polymer as a proton accepting material, wherein the second component has hydrogen bonding ability with the first component
Implementation Method 2
thermotropic hydrogels working on the basis of phase separation exhibited the best performance in terms of optical switching characteristic
Data Source
AI summary
The present disclosure is related to a non-volatile thermotropic composite material comprising a first component comprising a non-aqueous and non-volatile proton donating material; a second component comprising a monomer, an oligomer or a polymer as a proton accepting material; a non-volatile polymeric matrix; and wherein the non-volatile polymeric matric, the first component and the second component are configured to maintain at least one property which is reversibly changeable based on thermal energy received by or given out from the non -volatile thermotropic composite material. Proton donating materials include ionic liquid, poly(ionic liquid) and deep eutectic salt. The proton accepting material comprises at least an ether, a phenyl ester, an amide and an acrylate functional group. Also disclosed is a method of making said composite material comprising providing the first and second components and a non -volatile polymeric matrix and curing the mixture to form the non-volatile thermotropic composite material. The non-volatile thermotropic composite material can be used in smart windows.