W/O/W Double Emulsion for slow fragrance/extracts release

Hello fellow formulators,

     I'm trying to develop a double emulsion water based system for slow fragrances/natural extracts release. In order to develop such a system 
I use Glycol Distearate (HLB  = 1) and tween 20 (HLB = 16.7).

Recipe profile

Phase 1 (90% of total recipe)
Water 90%
Glycol Distearate 10%

Phase 2 (10% of total recipe)
Water 19%
Tween 20%
Extracts/Fragrances 55%
Sodium Benzoate, DHDH Hydantoin 6% 

I melt and emulsify the Glycol Distearate in water of 80C (176F) degrees at 2500rpm for 2 mins, and then when it cools (room temp) I add my extract/fragrance mixture which is also pre-emulsified with water and tween 20 (2500rpm 2 min). 

I mix the two phases at 4500rpm using a Silverson AX-1 batch mixer for 2 mins and then I get a white and stable emulsion.

I read from different publications that double emulsions tend to be cloudy or transparent due to lower particle size (micro or nano)

1. Do you consider my emulsion a double emulsion?
2. If not could you please make any suggestions on what to change/try?


Thank you.

Comments

  • Bill_TogeBill_Toge Member, Professional Chemist
    first of all, W/O/W emulsions are somewhat specialist, difficult to make, and very unusual in cosmetics; if memory serves, L'Oreal have a number of extant patents related to their usage in cosmetic products, so if you're planning to make this a commercial product at any point I'd strongly suggest you do a patent search, and find out what you can and can't do

    secondly, W/O/W is a water-in-oil emulsion emulsified into water, which is not what you have there; phase 2 is an oil-in-water emulsion 
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • Dear Bill_Toge thank you very much for your answer. 

    Phase 2 is water in oil if I'm not mistaken and the reason that the oils are in abundance is to make very fine droplets of oil with the minimum possible water. 

     I first develop the water in oil emulsion is stage 2. Due to the difference of the HLB I suspect that the lipophile parts of the two emulsifiers with come together due to Van der Waals interactions making a firmer double emulsion bubble around the extracts. 

    I not sure though if this is really happening. I just make a hypothesis and of course any feedback would be perfectly appreciated.

    I would definately check patents and research publications. Thank you for the advice.
  • 1) Glycol Distearate has little, if any, emulsifying "power". It is primarily used for opacifying and creating a pearl effect.
    2) I do not know of any Tween products that are suitable as W/O solubilizers.
    3) Like Bill said, W/O/W are a "B word" to make, much less make stable. I would go a different route if I were you.
  • Bill_TogeBill_Toge Member, Professional Chemist
    @manstra, on the contrary, your dispersed phase is oil and your continuous phase is water, hence: oil in water

    whether an emulsion is O/W or W/O has nothing to do with the relative volumes of the two phases, and everything to do which emulsifiers you use; and @Iaskedbetter is right, Tweens are far too hydrophilic to act as W/O emulsifiers

    you're right about the two lipophilic parts coming together, but that does not make it a double emulsion - if you have multiple surface-active materials on the same interface, it's still a single emulsion 

    the diagram below shows a W/O/W emulsion (blue = water, yellow = oil, white = emulsifier)

    image

    and this diagram shows the system you've made (blue = water, yellow = oil, white = Tween 20, orange = glycol distearate)

    image

    hope this helps!
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • BobzchemistBobzchemist Member, PCF student
    For a multiple emulsion, the emulsifier layers around the W/O droplets (discontinuous phase) have to be strong enough to keep the water in them from merging with the water of the continuous phase. As @Iaskedbetter said, none of the Tween range will be able to do this.

    This is a very, very complicated and difficult way to get a timed-release fragrance product. Have you looked at other emulsion systems first and already determined that they are unsuitable? LC emulsions would probably do what you need with far fewer hassles.
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
  • manstramanstra Member
    edited May 2015
    Thank you @Bill_Toge for that clear and very analytical reply. I agree with you that the most probable emulsion that I created is the one described in picture 2. Do you also consider that my approach with give a timed release product?

    @Iaskedbetter which route would you take?

    @Bobzchemist thank you for that answer. I will give you a better idea on which systems I worked in order to develop such a system. The essential oils I used were rosmarinus officinallis leaf extract, levandula angustifolia extract, Ocinum Basilicum extract,Cympopogon nardus oil and I have to say that I observed differences on the odour duration of release and intensity on my skin with certain systems. The measurement I do at the moment is only qualitative since I'm in the beginning of developing an insect repellent product.

    Emulsification systems:
    Span 80 - Tween 60 --> 1-2 hours duration, Strong intensity in odour
    PEG-12 Dimethicone - PEG 40 Castor oil - Glycol Distearate   --> 3-4 hours duration , lower intensity in odour
    Tween 20 - Glycol distearate --> 7-8 hours, even lower intensity not sure about effectiveness.

    Could you suggest a liquid crystal emulsifier?Do I need to make lyophilization in order to entrap the emulsified system and re-emulsify it?

    Kind regards to all

    All the extract emulsification is done under ambient conditions.
  • BobzchemistBobzchemist Member, PCF student
    You can search for a liquid crystal emulsifier and find more, but these are common:

    Olivem 1000 by itself or plus Olivem® VS Feel;  Montanov 68; Arlacel™ LC

    Also look at Pemulen for another way to emulsify
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
  • It sounds like what you are really looking for is a perfume fixative. There are a myriad of options to choose from so I would play around with a few to get your desired effect.

    More complicated routes would be some type of encapsulation tech or possibly coupling the fragrance material with an adsorbent that would somehow equalize the vapor pressure of the fragrance/oil? Silica shells come leaping to mind.

    That's really me just spitballing. I personally have not done much with slow release fragrance technology.
Sign In or Register to comment.