Polymer-Bound UV Absorbers for Skin Persistence
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Solution Overview
Problem
Current UV absorbers in personal care compositions face challenges such as low persistence on the skin, photodegradative effects, and limited broad-spectrum protection, particularly for water-soluble molecules like PABA and labile UV absorbers like avobenzone, which degrade over time and reduce their efficacy.
Innovation Solution
The development of polymer-bound UV absorbers, where UV absorber units are covalently bonded to a polymer backbone or side chains, enhancing their stability and persistence, and providing broad-spectrum protection without increasing the UV absorber content, by using structures like those with Chr-X residues and R groups, which are part of the polymer backbone or side chains, allowing for customizable UV spectrum protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-soluble UV absorbers like PABA are used, then UV protection is provided, but persistence on skin is low and they degrade quickly
Solution Approach 1:
The patent combines UV absorber molecules with polymer chains to create composite polymer-bound UV absorbers. This composite structure integrates the UV protection functionality of small molecules with the persistence and stability characteristics of polymers, resolving the contradiction between providing UV protection and maintaining long-lasting performance on skin.
Solution Approach 2:
The patent merges UV absorber units with polymer backbones or side chains through covalent bonding. This merging creates a single integrated structure where the UV absorber is permanently attached to the polymer, eliminating the separation between the UV protective function and the persistence-providing carrier, thereby simultaneously achieving both UV protection and long duration of action.
2Reliability
If labile UV absorbers like avobenzone are used, then UV-A protection is effective, but they photodegrade over time reducing efficacy
Solution Approach 1:
The patent creates composite structures where labile UV absorbers are covalently bonded to polymer backbones. This composite approach provides the UV-A absorption efficacy of molecules like avobenzone while the polymer matrix protects against photodegradation, thereby simultaneously achieving effective UV-A protection and stability.
Solution Approach 2:
The polymer backbone acts as an intermediary that stabilizes the labile UV absorber. The covalent bond between the UV absorber and polymer creates a protective linkage that prevents direct exposure to degradation pathways while maintaining the UV absorber's functional integrity, thus mediating between the need for effective UV absorption and the need for photostability.
3Reliability
If UV absorber content is increased to enhance protection, then broader spectrum coverage is achieved, but formulation complexity and cost increase
Solution Approach 1:
The patent designs polymer-bound UV absorbers where a single polymer structure can incorporate multiple UV absorber units with different spectral characteristics. This multi-functional design allows one formulation to provide broad-spectrum protection across UV-A, UV-B, and UV-C ranges without requiring separate formulations for each wavelength range, thereby achieving comprehensive protection while reducing formulation complexity.
Solution Approach 2:
The patent merges multiple UV absorber functionalities into a single polymer-bound structure. By covalently attaching different UV absorber units to the same polymer backbone or side chains, the invention consolidates what would traditionally require multiple separate UV absorber compounds into one integrated system, achieving broad-spectrum coverage without proportionally increasing formulation complexity.
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 polymer-bound UV absorbers exhibit improved water resistance, reduced skin penetration, and enhanced performance, stabilizing labile UV absorbers like avobenzone, thereby providing long-lasting and effective UV protection across the UV-A and UV-B spectrum.
Implementation Method 1
polymer-bound ultraviolet (UV) absorbers... providing broad-spectrum protection... enhanced performance... effective UV protection across the UV-A and UV-B spectrum
Data Source
AI summary
Personal care compositions comprising a polymer-bound UV absorber are described that provide enhanced properties, including customizable UV spectrum protection, broad-spectrum UV spectrum protection, water resistance, and labile UV stabilization. The polymer comprises anhydride functionality, such as maleic anhydride or a derivative thereof, and the UV absorber contains at least one hydroxyl, primary amine, or secondary amine group.The personal care compositions may be used to treat and/or protect against burns, cancers, erythema, lentigo (“liver spots”), keratotic lesions, wrinkles, and cellular changes of the skin; and/or color changes, embrittlement, lack of luster, tangles, split ends, and/or unmanageability of the hair.