Polyelectrolytes and their effect on waxes

The initial introduction consists of sodium polyacrylate and a wax, and any wax can be used. Called “CPW”, which stands for “Cold Process Wax”, the concept of cold process and waxes is not something formulators thought possible, until now. Any wax can disperse in cold water if it is a Jeesperse CPW version of that wax. Table 1 is a list of current Jeesperse CPWs. Waxes with melt points as high as 107°C have been converted to a Jeesperse CPW (now referred to as ‘the cold process wax’).

The process explained

Imagine making an emulsion in one vessel without heat and you still get to add a wax or two. Traditional emulsions require two vessels, one for the aqueous phase and another for your oil phase. The two vessels will require heat. A cold process wax emulsion requires one vessel that will not need to be heated. You have eliminated the energy and time required to heat your two vessels. Since your emulsion temperature has not been increased, a cool down process will not be necessary. The emulsions/hydro gels formed with the cold process wax will deliver textures and product forms that may not be possible using the traditional methods of making emulsions. How is this possible? We need to define the materials used to develop this technology. The definition of a wax is simply the origins of the material, whether it is natural or synthetic. Does it have a melt point above 40°C and, is it insoluble in water? Waxes are typically non-polar. Water is a very polar ingredient. One reason wax and water will not mix is because they are not the same polarity. The cold process wax will induce polarity in waxes. How do we induce polarity in a wax? We do this by bonding sodium polyacrylate to a wax or combination of waxes. Sodium polyacrylate is a salt, a polysalt. A salt has certain properties; it disassociates in water and has the ability to induce an electrostatic charge once in water. Sodium polyacrylate has two types of molecular configuration. When not in water the molecular configuration is called a random coil. When mixed with water it disassociates into sodium cations (+) and polyacrylate anions (–). The electrostatic charge induced in the water will have an effect on the configuration of this molecule. It is no longer configured into a random coil. The polyacrylate anions start to repel each other and this leads to a straightening out of this random coil. In a linear configuration the polyacrylate anion starts to achieve polymeric attributes. As a polymer, it tends to be big. The structure of the polymer contains a multiple hydrophilic structure that carries a charge along a linear hydrocarbon backbone. This gives the polymer its function. It holds water in place creating a hydro gel. The polyacrylate anion polymer will have an affinity for other molecules that share this linear hydrocarbon configuration. This is why you can add oils into a hydro gel made with sodium polyacrylate. A wax has a linear hydrocarbon configuration. The wax and polyacrylate anion will form a physical bond. This bond will not only be structural but functional. The wax will now behave like the polyacrylate. Polyelectrolytes and conventional emulsifiers such as sodium stearate or stearic acid have similar structures and therefore similar functions. A conventional emulsifier will have a lipophilic backbone and a hydrophilic end. In an emulsion it induces polarity in the lipophilic phase. This “polar” oil phase in water is now a micelle. The hydrophilic ends create a repelling force that keeps each micelle form coalescing. The cold process waxes follow the same principles used to describe existing emulsion technologies. The only difference is that we now know that these principles can be applied to waxes.

Analysis

We analysed the cold process waxes on a Differential Scanning Calorimeter (DSC). A DSC will measure a material’s melt point. The DSC will also measure the amount of energy it takes to melt a wax. This data point is called a material’s “heat of fusion” or “heat of disassociation”. Since we do not need to heat the cold process wax when making an emulsion, we can theorise that we would reduce the energy needed to disassociate a wax. The data confirmed this theory and we do see reductions in the heat of disassociation in all cold process waxes. This reduction essentially means the cold process wax lowers the energy it takes to separate wax molecules. Figure 2 shows how changes in the amount of sodium polyacrylate impact the heat of disassociation. We can see how this difference is changing the heat of disassociation of the wax. The sunflower wax used to produce CPW-S had a heat of fusion of 208.6 (J/g). A 30% addition of sodium polyacrylate reduced this value to about 138 (J/g). An emulsifier is described as having a lipophilic backbone with a hydrophilic end. A polyelectrolyte has a backbone that is lipophilic and many branches along this backbone that are hydrophilic. This difference can be seen and felt when evaluating emulsions made from these two materials. An emulsifier will create a micelle whereas a polyelectrolyte creates a lamellar emulsion. The fact that we did not melt the wax in the oil phase of the emulsion will change the way a cold process wax emulsion performs. The polyacrylate/wax will form a lattice structure that holds water and oil. There are many polyelectrolytes to choose from. There are polyacrylic acids like the sodium polyacrylate, carbomer, or copolymers of polyacrylic acids. There are many natural types to choose from. Natural gums such as pectin, alginates, and carrageenan can be used to create a cold process wax. So you can see there are many combinations that can lead to fully natural systems. There are many industries that use polyelectrolytes, such as industrial uses in wastewater treatment or adjusting flow characteristics of cement. The food industry uses these gums for thickening and texture, and applications in industrial coatings and biocompatible substrates are areas of research. Coating the surface of a material can create a surface that responds to changes in its surroundings and an increase in moisture makes the substrate soft and can lead to the release or intake of an active, drug, or a functional substance. Jeen International has applied for patents in the use of polyelectrolytes to induce polarity in waxes which allows a wax to be dispersed in cold water.