Tunable Optical Device Liquids for Low-Swelling PDMS Membranes
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Solution Overview
Problem
Existing optical devices using liquid-elastomer technology face issues with solubility and swellability due to the interaction between the liquid and the elastomer membrane, leading to instability and performance degradation under varying environmental conditions.
Innovation Solution
The use of a silicone-based polymer with specific side chains and substituents, such as polydimethylsiloxane (PDMS), which limits solubility and diffusion to prevent membrane swelling, ensuring compatibility and stability across a range of temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a liquid is used to fill the volume in an optical tuneable device, then the optical behavior can be adjusted by changing membrane curvature, but the liquid causes solubility and swelling effects in the elastomer membrane
Solution Approach 1:
The patent changes the physical and chemical parameters of the liquid by using a polymer with specifically adjusted glass transition temperature (Tg between -100°C to 0°C) and tailored chemical composition. This parameter optimization allows the liquid to remain fluid at operating temperatures while minimizing solubility and swelling effects on the PDMS membrane, thus maintaining membrane composition stability while enabling optical tuning.
Solution Approach 2:
The patent employs a composite material system consisting of polydimethylsiloxane (PDMS) as the base polymer with specifically selected liquid polymer fillers. The composite structure leverages the chemical inertness and low solubility parameters of PDMS while incorporating liquids with matched Tg and viscosity properties, creating a synergistic system that reduces membrane swelling while maintaining optical adjustability.
2Quantity of substance
If the liquid penetrates the membrane surface and bulk, then solubility increases, but this leads to extensive swelling of the membrane
Solution Approach 1:
The patent optimizes the glass transition temperature parameter of the liquid polymer to be between -100°C to 0°C, which ensures the liquid remains in a flexible state while having reduced molecular mobility for penetration. The chemical composition parameters are also adjusted to match solubility parameters with PDMS, minimizing the thermodynamic driving force for liquid molecules to penetrate and swell the membrane.
Solution Approach 2:
The patent converts the potential harmful effect of liquid-polymer interaction into a beneficial low-swelling system by carefully selecting liquids with Tg in the -100°C to 0°C range. These liquids have sufficient molecular motion to provide optical tuning functionality but restricted penetration capability, thus transforming what could be a swelling problem into a stable, tunable system.
3Reliability
If PDMS membranes are used for tuneable lenses, then low-temperature flexibility and UV stability are achieved, but solubility and swellability issues occur with conventional liquids
Solution Approach 1:
The patent creates a composite material system where PDMS serves as the stable membrane matrix and liquid polymers with specifically adjusted Tg (-100°C to 0°C) and chemical composition serve as the filler. This composite structure maintains the inherent UV and heat stability of PDMS while the carefully selected liquid polymers have reduced solubility parameters, minimizing composition instability and swelling while preserving the optical tuning 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 silicone-based polymer maintains membrane integrity and optical performance by minimizing swelling and diffusion, allowing for tunable lenses with improved stability and adaptability to various environmental conditions.
Implementation Method 1
A suitable molecule needs to contain a spectrum of properties where the chemical affinity to the membrane environment such as a PDMS matrix and the 3-dimensional structure and stability of the membrane are in balance. An important role plays a low solubility (typically less than 1.5% %) so the molecules of the liquid do not penetrate the surface nor bulk of the surrounding polymer network of the membrane so as to avoid extensive swelling of the membrane.
Implementation Method 2
The liquids of the invention allow the use of PDMS and substituted PDMS in a broad spectrum of possible applications with different requirements applying the many positive properties, such as low-temperature flexibility, long-term stability under UV, heat and moisture stability and high transmission.
Data Source
AI summary
The present invention relates to an optical tuneable device comprising a volume and a polydimethylsiloxane (PDMS) membrane, wherein the membrane delimits the volume at least partially and the volume is filled with a silicone-based polymer of formula 1,with R1 being an alkyl moiety, —(CH2)-phenyl, phenyl, CF3 or alkyl-CN moiety, R2 to R8 being —H, an alkyl, (CH2)-phenyl or phenyl moiety. The polymer may optionally be substituted by —F. Furthermore, the present invention relates to the use of said polymer in an optical tuneable device.