42 SILICONES A B C D
Figure 2: Vials on the left contain trisiloxanyl-cannabidiol (orange); vials on the right contain hemp oil (green). A) Two pieces of silicone elastomer before submersion in trisiloxanyl-cannabidiol and hemp oil, respectively. B) Silicone pieces placed in oils and left with closed lids at time = 0 minutes. C) Silicone pieces after 30 minutes in oil. D) Silicone pieces after removal from oil: the silicon piece placed in trisiloxanyl-cannabidiol has swollen and taken on a visibly orange tint, indicating absorption of the oil; the silicon piece placed in hemp oil shows no change, indicating no oil absorption.
Trisiloxanyl-cannabidiol loaded in PDMS gel In a second example, trisiloxanyl-cannabidiol was added to polydimethylsiloxane and cured into the gel. To accomplish this, two parts were prepared. For part A, 21.8 g vinyl-terminated polydimethylsiloxane (Gelest Gel D200A) and 0.8 g fumed silica (CAB-O-SIL M5) were added to a Flacktek® cup and mixed by hand until the silica was incorporated. In a vial, 7.2 g of the D5 replacement propyltrisiloxane (SiBrid® TM-031) and 7.2 g trimethylsiloxysilicate resin (Dowsil® MQ 1600) were added together and heated at 80°C until the mixture was homogeneous. Once the mixture cooled, it was added to the Flacktek® cup along with 0.2 g trisiloxanyl- cannabidiol and all components were combined using a Flacktek® mixer. Part B (Gelest Gel D200B) was then added and incorporated using the Flacktek® mixer. As a control, a PDMS gel containing hemp
seed oil was prepared according to a similar process. In lieu of trisiloxanyl-cannabidiol, 2.0 g of Cannabis Sativa seed oil (hemp seed oil) was added to achieve a similar CBD loading level into the gel. Exact formulations for the two gels are summarised in Table 2. Both formulas were poured into individual 2-inch diameter aluminum pans and cured in the oven at 105°C for 80 minutes. The PDMS gel with trisiloxanyl-cannabidiol
cured into a free-standing gel appeared colourless and semi-transparent while the PDMS gel with hemp seed oil presented as yellow, sticky, and soft as shown in Figure 4. After sitting at room temperature for 24 hours, the PDMS gel with hemp seed oil developed a thin oil film on its surface, indicating separation of the hemp oil from the silicone gel. The PDMS gel with trisiloxanyl-cannabidiol showed no separation after 24 hours and remained a free-standing gel. These results demonstrate the more successful and facile incorporation of trisiloxanyl-cannabidiol into silicone formulations compared to alternative CBD- containing oils such as hemp seed oil.
CBD isolate
Release of CBD from silicone gel The trisiloxanyl ‘tipped’ tail of the CBD derivative promotes favourable interactions with silicone substrates. Trisiloxanyl- cannabidiol can be absorbed into a silicon substrate in a homogeneous fashion while maintaining optical clarity and stability
PERSONAL CARE April 2021
Hydrolyzed trisiloxanyl- Cannabidiol
TABLE 2: FORMULATIONS OF PDMS GELS CONTAINING HEMP SEED OIL AND TRISILOXONYL-CANNABIDIOL
Ingredients
Part A - Polydimethylsilicone Gel Propyltrisiloxane
Trimethylsiloxysilicate resin Fumed Silica
Cannabis Sativa Seed Oil Trisiloxonyl-Cannabidiol
Part B - Polydimethylsilicone Gel Trade Name
Gelest Gel D200A Sibrid TM-031
Dowsil MQ 1600 CAB-O-SIL M5 Hemp Seed Oil Vertasil TM-CBD1 Gelest Gel D200B
with no phase separation. Exposure of the silicon substrate loaded with the trisiloxane- cannabidiol to water results in hydrolysis at the silicon-oxygen-carbon linkage, releasing and reforming the original, fully active CBD molecule at the interface. The release mechanism is illustrated in Figure 5. This system has potential application use for the controlled release of CBD from silicone materials and future work will be focused on analysing the rates of controlled CBD release as well as interaction at the substrate-skin interface.
Conclusion CBD is used extensively in the personal care
Hemp
50.00 18.00 18.00 2.00 5.00 0.00 7.00
TM-CBD1 54.50 18.00 18.00 2.00 0.00 0.50 7.00
industry for a wide variety of applications. However, due to its inability to spread uniformly into a thin layer on the skin without further dilution in a suitable oil medium, pure CBD can be difficult to use when formulating products. Many CBD-containing products, such as hemp oil, contain only small amounts of CBD, and thus require large use levels in formulations to achieve appropriate CBD activity. Additionally, neither CBD isolate nor CBD-containing products are soluble in silicone oils or compatible with silicone materials. Since silicone materials are used extensively in personal care applications, there is an entire market segment currently unable to effectively use CBD in its products. Vertasil TM-CBD1 (trisiloxanyl-cannabidiol)
Other components
CBD Washes from silicone gel
is a material specifically designed to address the current limitations on CBD use in personal care applications, with an expanded solubility profile to silicone oils and easy integration into silicone gels. This new product is anticipated to enable many applications, including soft skin adhesives, scar reduction treatments, transdermal patches, and anti- wrinkle face masks. Furthermore, Vertasil TM-CBD1 is easily incorporated by creating a thin emollient film and provides lubricity and softness without the greasiness of natural oils. Vertasil TM-CBD1 also has the potential to be used for controlled CBD release. Since this material is a CBD derivative, it may rely on a different set of federal and state regulations than CBD itself, which may be important for interstate transport, claims, and labelling. Vertasil TM-CBD1 is a unique, unmatched material that will expand the use of CBD in the personal care industry.
Figure 3:TLC plate showing the presence of CBD in hydrolyzed trisiloxanyl-cannabidiol and in the three washes from the gel.
References 1. Corroon J, Phillips JA. A Cross-Sectional Study
www.personalcaremagazine.com
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