BEHENTRIMONIUM CHLORIDE

This study aims to use electrokinetic analysis to investigate the deposition behaviour and conditioning efficacy of cationic surfactants on human hair, focusing on how surfactant structure, concentration and hair damage influence performance. It also aims to understand the mechanisms governing surfactant adsorption and their impact on hair manageability and health. This research employed streaming potential measurements-including pH-dependent, time-dependent and concentration-dependent zeta (ζ)-potential studies-alongside wet combing analyses and ATR-FTIR spectroscopy to evaluate the adsorption affinity and conditioning effects of four cationic surfactants: behentrimonium chloride (BTMC), behentrimonium methosulfate (BTMS), hexadecyltrimethylammonium chloride (CTAC) and stearylalkonium chloride (STAC). A simplified model surface using silicon oxide (Si | SiO 2 ) wafers was also utilized to isolate the influence of hair's natural variability and fibrous structure. Longer-chain surfactants like BTMC showed superior deposition and conditioning due to stronger van der Waals interactions, while bulky groups in STAC hindered deposition. BTMC outperformed BTMS, likely due to the chloride counterion's higher mobility. BTMC and BTMS were superior against CTAC and STAC due to their longer carbon chain length. Wet combing analyses revealed that BTMC significantly reduced combing forces, improving manageability, whereas STAC fared the worst due to its low adsorption. However, ATR-FTIR analysis indicated no reversal of oxidative damage, suggesting conditioners improve manageability without repairing structural damage. The study highlights the importance of surfactant molecular structure-such as carbon chain length and counterion type-in deposition efficiency and conditioning performance, providing valuable insights for developing more effective hair care formulations. By leveraging electrokinetic analyses in the form of streaming potential experiments, we were able to quantitatively assess adsorption behaviour, ζ-potential changes and the dynamic interactions between surfactants and hair. These findings enhance the understanding of cationic surfactant-hair interactions, offering practical implications for optimizing conditioners to improve user experience and hair health. Cette étude vise à utiliser une analyse électrocinétique pour évaluer le comportement de dépôt et l'efficacité de conditionnement des tensioactifs cationiques sur les cheveux humains, en se concentrant sur la façon dont la structure et la concentration des tensioactifs et le degré de dommage capillaire influencent les performances. Elle vise également à comprendre les mécanismes qui régissent l'adsorption des tensioactifs et leur impact sur la facilité de coiffage et la santé des cheveux. MÉTHODES: Cette recherche a utilisé des mesures du potentiel de diffusion (études de potentiel zêta [ζ] en fonction du pH, du temps et de la concentration), ainsi que des analyses de peignage humide et une spectroscopie ATR‐FTIR pour évaluer l'affinité d'adsorption et les effets de conditionnement de quatre tensioactifs cationiques: chlorure de béhentrimonium (BTMC), méthosulfate de béhentrimonium (BTMS), chlorure d'hexadécyltriméthylammonium (CTAC) et chlorure de stéaralkonium (STAC). Un modèle de surface simplifié utilisant des plaquettes d'oxyde de silicium (Si |SiO 2 ) a également été utilisé pour isoler l'influence de la variabilité naturelle des cheveux et de la structure de la fibre capillaire. RÉSULTATS: Les tensioactifs à longue chaîne, comme le BTMC, ont montré un dépôt et un conditionnement supérieurs en raison d'interactions de Van der Waals plus fortes, tandis que les groupes volumineux en STAC ont limité le dépôt. Le BTMC a surp

Cationic guar is an important polysaccharide used as a hair conditioning agent in personal care products. In this article, we report streaming potential data demonstrating its behaviour as it interacts electrostatically with hair. Several cationic guar variants with different molecular weights (MWs) and charge densities (CDs) were examined. All experiments were carried out with a custom-designed streaming potential instrument so that in situ, real-time data were monitored during the treatment of a hair plug with aqueous solutions of cationic guar and subsequent treatment with anionic surfactants-sodium laureth sulfate (SLES) and cocamidopropyl betaine (CAPB)-commonly found in contemporary shampoo formulations. The MW of the cationic guar variants plays an integral role in determining the thickness of the adsorbed polymer layer on the hair surface while CD influences the zeta potential. Data were also generated for the treatment of hair with a cationic flexible polymer (polyquaternium-28) and cationic conditioning surfactant (behentrimonium chloride) to provide a frame of reference. The deposition behaviour on hair of high MW cationic guar variants is distinct from these conventional molecules in terms of its electrokinetic properties. We also examined the electrokinetic behaviour of cationic guar on hair types from different racial backgrounds. While the cationic guar treatment yielded similar results for the different hair types, anionic surfactant treatment resulted in quicker sorption and desorption from African, European 65% grey, and Mulatto hair as compared to Chinese, European dark brown, and Indian hair. We introduce an in situ technique for measuring the dynamic sorption/desorption of charged molecules on the surface of human hair. Evaluation of a series of cationic guar species revealed varying behaviour depending on the MW and CD of the polysaccharide. Our data also demonstrate differences in the desorption properties of typical shampoo surfactants for hair from diverse racial backgrounds. Le guar cationique est un polysaccharide important utilisé comme conditionneur capillaire dans les produits cosmétiques. Dans ce rapport, nous démontrons l'utilisation de la technique du potentiel de streaming pour étudier comment le guar cationique interagit électrostatiquement avec les cheveux. Plusieurs variantes del guar cationique avec différents poids moléculaires et densités de charge ont été examinés. MÉTHODES: Nous avons utilisé un instrument de potentiel de streaming pour les expériences. Les études ont été réalisées en temps réel pour surveiller le traitement de cheveu avec des solutions aqueuses de guar cationique suivi d'un traitement ultérieur avec tensioactifs anioniques comment le sulfate de laureth de sodium et le cocamidopropyle bétaïne, des ingrédients généralement trouvés dans les formulations de shampooing. RÉSULTATS: Le poids moléculaire des variants du guar cationique joue un rôle intégral dans la détermination l'épaisseur de la couche de polymère adsorbée sur la surface des cheveux tandis que le densité de charge influence le potentiel zêta. Des données ont également été générées pour le traitement des cheveux avec un polymère flexible (polyquaternium-28) et tensioactif de conditionnement cationique (behentrimonium chlorure) pour fournir un cadre de référence. Le comportement de dépôt sur les cheveux des variants de guar cationiques à poids moléculaire élevé est distinct de ces molécules conventionnelles en termes de ses propriétés électrocinétiques. Nous avons également examiné le comportement électrocinétique de guar cationique sur des types de cheveux de différents milieux raciaux. Le traitement

Behentrimonium chloride (BTC) is a straight-chain alkyltrimonium chloride compound commonly used as an antistatic, hair conditioning, emulsifier, or preservative agent in personal care products. Although the European Union recently restricted the use of alkyltrimonium chlorides and bromides as preservatives to ≤0.1%, these compounds have been safely used for many years at ≤5% in hundreds of cosmetic products for other uses than as a preservative. In vitro, clinical, and controlled consumer usage tests in barrier-impaired individuals were conducted to determine if whole body, leave-on skin care products containing 1-5% BTC cause dermal irritation or any other skin reaction with use. BTC-containing formulations were predicted to be non-irritants by the EpiDerm® skin irritation test and the bovine corneal opacity and permeability (BCOP)/chorioallantoic membrane vascular assay (CAMVA) ocular irritation test battery. No evidence of allergic contact dermatitis or cumulative dermal irritation was noted under the exaggerated conditions of human occlusive patch tests. No clinically assessed or self-reported adverse reactions were noted in adults or children with atopic, eczematous, and/or xerotic skin during two-week and four-week monitored home usage studies. These results were confirmed by post-marketing data for five body lotions, which showed only 0.69 undesirable effects (mostly skin irritation) reported per million shipped consumer units during 2006-2011; a value consistent with a non-irritating body lotion. No serious undesirable effects were reported during in-market use of the products. Therefore, if formulated in appropriate conditions at 1-5%, BTC will not cause dermal irritation or delayed contact sensitization when used in a whole-body, leave-on product.

The aim of this study was to establish the repeatability measures of quantitative Gaussian and non-Gaussian diffusion metrics using diffusion-weighted imaging (DWI) data from phantoms and patients with head-and-neck and papillary thyroid cancers. The Quantitative Imaging Biomarker Alliance (QIBA) DWI phantom and a novel isotropic diffusion kurtosis imaging phantom were scanned at 3 different sites, on 1.5T and 3T magnetic resonance imaging systems, using standardized multiple b-value DWI acquisition protocol. In the clinical component of this study, a total of 60 multiple b-value DWI data sets were analyzed for test-retest, obtained from 14 patients (9 head-and-neck squamous cell carcinoma and 5 papillary thyroid cancers). Repeatability of quantitative DWI measurements was assessed by within-subject coefficient of variation (wCV%) and Bland-Altman analysis. In isotropic diffusion kurtosis imaging phantom vial with 2% ceteryl alcohol and behentrimonium chloride solution, the mean apparent diffusion (D app × 10 -3 mm 2 /s) and kurtosis (K app , unitless) coefficient values were 1.02 and 1.68 respectively, capturing in vivo tumor cellularity and tissue microstructure. For the same vial, D app and K app mean wCVs (%) were ≤1.41% and ≤0.43% for 1.5T and 3T across 3 sites. For pretreatment head-and-neck squamous cell carcinoma, apparent diffusion coefficient, D, D*, K, and f mean wCVs (%) were 2.38%, 3.55%, 3.88%, 8.0%, and 9.92%, respectively; wCVs exhibited a higher trend for papillary thyroid cancers. Knowledge of technical precision and bias of quantitative imaging metrics enables investigators to properly design and power clinical trials and better discern between measurement variability versus biological change.