Swelled Polymer UV Compositions with Inorganic Nanoparticles
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Solution Overview
Problem
Current UV-protective compositions, particularly sunscreens, face challenges in providing broad-spectrum protection against both UVA and UVB radiation while being safe for human skin, as they often contain nanoparticles that raise regulatory concerns and may cause skin damage due to free radical generation and absorption into the skin. Additionally, physical sunscreens are opaque and leave a white cast, and chemical sunscreens may not adequately protect against UVA radiation.
Innovation Solution
The development of UV-protective compositions comprising swelled polymer matrix macroparticles with inorganic nanoparticles of UV-protective agents, such as doped or undoped solid inorganic crystals, dispersed and embedded in a thermoplastic polymer matrix, which provide broad-spectrum protection by absorbing UV radiation from 280 nm to 400 nm without the need for additional ultraviolet-absorbing agents, while being transparent and reducing the risk of nanoparticle migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical sunscreen compositions use relatively large particles of inorganic materials to obtain absorption and reflection of ultraviolet radiation over the full UVA and UVB range, then UV protection is improved, but the compositions become viscous and opaque and leave a white cast on the skin
Solution Approach 1:
The patent segments the inorganic UV-protective material into nanoparticles with a mean particle size of less than 100 nm, specifically 1-50 nm. This segmentation allows the material to maintain UV protection while becoming transparent to visible light, eliminating the white cast and opacity issues associated with larger particles.
Solution Approach 2:
The patent changes the critical parameter of particle size from micrometer scale to nanometer scale (mean particle size less than 100 nm). This parameter change fundamentally alters the optical properties, enabling the material to scatter UV radiation while being transparent to visible light, thus resolving the contradiction between UV protection and transparency.
2Ease of operation
If chemical sunscreen compositions use organic compounds to absorb UV radiation and remain transparent on skin, then transparency is improved, but free radicals are generated causing skin damage and the compounds may be absorbed into the skin causing long-term health effects
Solution Approach 1:
The patent uses an organic polymer matrix as an intermediary carrier to hold the inorganic nanoparticles. The polymer matrix provides transparency and facilitates skin application, while the inorganic nanoparticles provide UV protection without generating free radicals. This intermediary approach combines the advantages of both chemical and physical sunscreens while avoiding their disadvantages.
Solution Approach 2:
The patent creates a composite material system consisting of inorganic UV-protective nanoparticles dispersed in an organic polymer matrix. This composite structure allows the inorganic particles to provide safe UV protection while the organic polymer provides transparency and proper rheological properties, achieving both transparency and safety simultaneously.
3Ease of operation
If nanoparticles of UV-protective agents are used to provide transparency on skin, then transparency is improved, but the range of wavelengths absorbed is reduced requiring combination of different UV-absorbing materials
Solution Approach 1:
The patent selects inorganic materials such as zinc oxide and titanium dioxide that inherently provide broad-spectrum UV protection across both UVA and UVB ranges even at nanoparticle sizes. These materials serve multiple functions: they absorb and scatter UV radiation across the full spectrum while remaining transparent to visible light, eliminating the need for combining multiple different UV-absorbing materials.
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
These compositions offer effective, broad-spectrum protection against UVA and UVB radiation, are transparent on the skin, and have reduced potential toxicity compared to nanoparticle-only compositions, maintaining the safety and efficacy of UV protection without the drawbacks of existing sunscreen types.
Implementation Method 1
nanoparticles of a UV-protective agent consisting of solid inorganic crystals... provide broad-spectrum protection by absorbing UV radiation from 280 nm to 400 nm
Implementation Method 2
the particles of inorganic material should be in the form of nanoparticles, which absorb and/or scatter UV light but not visible light, rendering them substantially transparent on the skin
Data Source
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AI summary
Disclosed are UV-protective compositions comprising swelled polymer matrix macroparticles comprising a thermoplastic polymer swelled with at least one swelling agent, and a plurality of nanoparticles of an inorganic UV-protective agent comprising at least one solid inorganic crystal and a dispersant associated with the crystal, wherein the inorganic nanoparticles are dispersed and embedded in the swelled polymer matrix macroparticles. Method of preparation and uses of such compositions are also provided.