Bridged Polysilsesquioxane Sunscreens Prevent Leaching
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Solution Overview
Problem
Current sunscreens face issues with UV stability and leaching, as well as photo-toxicity and photo-allergenic effects, due to the instability of organic absorber compounds under UV exposure, leading to reduced effectiveness over time.
Innovation Solution
Development of sunscreen compositions based on nanoparticles of bridged polysilsesquioxanes, where UV-absorbing monomers are covalently bonded with trialkoxysilyl groups and polymerized to form stable particles that prevent leaching and resist photo-degradation, using methods like sol-gel or microemulsion polymerizations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic absorber sunscreens are used to block UV radiation, then UV protection is provided, but photochemical stability deteriorates and leaching increases over time
Solution Approach 1:
The patent uses silica particles as an intermediary carrier to encapsulate organic sunscreen absorbers. The silica matrix physically entraps the organic molecules, preventing their direct exposure to UV radiation and subsequent degradation. This mediator approach allows the organic absorbers to function while protecting them from photochemical breakdown and leaching, resolving the contradiction between maintaining UV protection and improving photochemical stability.
Solution Approach 2:
The invention creates a composite material system combining inorganic silica particles with organic sunscreen absorbers. The composite structure integrates the UV-absorbing properties of organic compounds with the photostability and structural integrity of inorganic silica, achieving both effective UV protection and enhanced photochemical stability that neither component could provide alone.
2Reliability
If organic absorber sunscreens are applied to skin, then UV protection is achieved, but leaching occurs reducing long-term effectiveness
Solution Approach 1:
Silica particles serve as an intermediary containment structure that physically traps organic sunscreen molecules. This encapsulation prevents the organic absorbers from leaching off the skin while still allowing them to absorb UV radiation. The silica matrix acts as a stable carrier that anchors the organic compounds in place, eliminating leaching losses and ensuring long-term protection.
Solution Approach 2:
The silica particles form a matrix or shell structure that encapsulates the organic sunscreen absorbers. This shell confines the organic molecules within the silica matrix, preventing them from migrating or leaching away from the application site, thereby maintaining consistent UV protection without substance loss.
3Stability of the object's composition
If traditional silica particles are used to encapsulate sunscreens, then stability is improved, but photochemical degradation still occurs
Solution Approach 1:
The patent creates a composite material where organic sunscreen absorbers are integrated within an inorganic silica matrix. This composite structure combines the photostability of silica with the UV-absorbing capability of organic compounds, achieving resistance to photo-degradation that neither material could provide alone. The close integration in the composite ensures the organic molecules remain protected while maintaining their protective function.
Solution Approach 2:
The silica matrix acts as a protective intermediary between the organic sunscreen absorbers and the damaging UV radiation. By encapsulating the organic molecules within the silica structure, the matrix shields them from direct photochemical attack while still allowing the absorbers to function, thereby improving resistance to photo-degradation.
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 bridged polysilsesquioxane-based sunscreens demonstrate superior photochemical stability and minimal leaching, maintaining UV protection efficacy longer than traditional sunscreens, with comparable SPF values and reduced UV-induced degradation.
Implementation Method 1
UV-absorbing monomers are covalently bonded with trialkoxysilyl groups and polymerized to form stable particles that prevent leaching and resist photo-degradation
Implementation Method 2
covalently bonded with trialkoxysilyl groups and polymerized to form stable particles
Implementation Method 3
polymerized to form stable particles that prevent leaching and resist photo-degradation
Data Source
AI summary
Bridged polysilsesquioxane based sunscreens prepared as nanoparticles via oil/water microemulsion polymerization, sol-gel polymerizations, or a modified Stober process. Minimized leaching and decreased levels of photo-degradation were achieved with covalent incorporation, with bridged incorporation necessary to ensure isolation of the sunscreen and any photo-products from skin. SPF values of were found to be comparable to existing commercial sunscreens. Furthermore the bridged polysilsesquioxane based sunscreens can be classified as broad-spectrum, and rate from moderate to superior in terms of UVA protective ability.