Polymers

Polymers

Scientifically speaking, a “polymer” is a large molecule made up of repeating sequences of identical smaller molecules. But the definition doesn’t tell the bigger story: Polymers are essential for life. Thousands of different polymers exist in nature – including in our own bodies. Thousands of other polymers have been developed by humankind to perform a huge variety of functions that are central to modern living.   

Polymers come in many forms, including solids, liquids and waxes. In fact, the same polymer may be used as a liquid in one product and a solid in another. Plastics are an example of solid, man-made materials made from a combination of different polymers. But while all plastics are polymers, not all polymers are plastic. The vast majority of polymer ingredients used in cosmetics and personal care products, for example, are not plastic but are in liquid or other form. 
 

Polymers in Nature

The human body contains many natural polymers -- even the nucleic acids (DNA) and proteins that determine your genetic makeup are polymers.  The body is estimated to contain 100,000 different polymer-based proteins. Protein is a main component of skin, organs, muscles, hair and fingernails. The most common protein in your body, collagen, is used for support and structure.  Another polymer important in the skin is hyaluronic acid, which is the main molecule of the extracellular matrix of the skin and also is present in the synovial fluid that lubricates your joints. 

Cellulose, another natural polymer, is the main structural component of plants.  Cellulose is the most abundant organic compound on Earth, and its purest natural form is cotton. The cellulose in vegetables and grains is the fiber in our foods. Chitin, a “polysaccharide” polymer similar to cellulose, is the fundamental substance in the exoskeletons of crustaceans, insects, and spiders. 

One natural polymer that we eat a lot of is protein; it’s an essential nutrient for health.   Meat carries a lot of protein; nearly all vegetables, beans, grains, nuts, and seeds contain some; and gelatin is made of water soluble protein.  Protein also forms some of the materials human wear: leather, silk, and wool. 
 

Polymers in Medicine

Polymers are used in scores of industries for countless beneficial purposes, but no advances in polymer science are more striking than those in modern medicine. Medical applications range from important day-to-day products such as latex gloves, bandages, and tubing, to applications as advanced as self-tying sutures, implantable medical devices, and artificial joints. 

Research in cancer treatment has harnessed specially-designed polymeric nanomaterials as delivery mechanisms that allow for targeted delivery of medicines directly to tumor tissue. Advancements in biodegradable polymers have created biomedical “scaffolds” that support tissue growth, and then degrade slowly once implanted in the body.  In a more traditional medical use, a polymer called polyethylene glycol 3350 is available as a FDA-approved oral laxative.  
 

Polymers in Personal Care and Cosmetics

The addition of polymers has led to better performance for many personal care and cosmetic products, providing benefits not available before, such as water resistance or “sweat-proof” characteristics and other long-lasting properties. A broad spectrum of natural, organic and synthetic polymers are used in a wide range of cosmetic and personal care products to serve a variety of functions, such as thickening, emulsifying (keeping ingredients mixed together), creating protective films or barriers, and making products feel either “drier” or more moist, smoother, or more pleasant overall.

Another advantage of polymers is that they are “high molecular weight,” which means they do not easily penetrate the skin and are less likely than traditional alternatives to cause stinging, burning or redness.

Here’s a review of the way polymers are used in personal care products and cosmetics:

Thickeners 

  • Water-based formulations are thin by nature, and polymers are used to thicken them or turn them into gels. When used to increase thickness in products like shampoos, conditioners, creams, and lotions, for example, the formulas feel more rich, smooth, and creamy. 
  • Natural polymers such as starch, xanthan or guar gum, carrageenan, alginates, polysaccharides, pectin, gelatin, agar, and cellulose derivatives can be used for this purpose. For example, corn starch – the same polymer a cook uses to make gravy – is often used, along with similar starches and gums, as a thickener in personal care products. 
  • On the synthetic side, polyacrylate derivatives and polyacrylamide polymers are most popular for this purpose. These polymers, for example, make it possible for the alcohol hand gels to stay “gelled” so you can carry them around without leakage. They thicken hair color products so that the color stays where applied, non-drip.
  • More recent developments include combining hydrophobic (water-resisting) and hydrophilic (water-attracting) polymers into “copolymers” that stabilize products so that they don’t get thin under high heat – for example, sunscreens at the beach or in a hot car – or require you to shake a product before use.

Structuring Agents

  • Structuring agents add rigidity; these include natural and synthetic waxes, lanolin, long-chain fatty alcohols, and triglycerides. A popular component, poly-alpha-olefin, is used in products like eye shadows and lip products because it adds structure without feeling greasy. Glycol stearates make products opaque and add a pearlizing effect. 
  • One of the latest innovations in cosmetics involving polymers is the concept of “3D makeup printing,” which allows consumers to create their own custom-color makeup.
  • Water resistance/Sweat proof/Long lasting
  • Film-forming polymers are critical to provide water resistance and sweat resistance benefits to sunscreens so your family can enjoy a day at the beach.
  • Polyurethanes are used in nail products and water-resistant mascara to make them long lasting because they form strong films.

Hair Styling Products

  • Polymers in hair products include natural substances such as polysaccharides, including starch and cellulose derivatives, natural gums, and hydrolyzed proteins. Synthetic hair-friendly polymers include polyvinyl pyrrolidone and acetate, polyvinylamides, polyacrylates and polymethacrylates, polyurethanes, and silicones.
  • Polymers help control your hair style in windy or humid conditions, minimize frizz and fly-aways, and give consumers choices in finish such as crisp hold or soft natural feel. You’ll find them in sprays, lotions, gels, and foams.

Delivery Systems

  • Polymers can serve as delivery systems for active ingredients in cosmetics, such as antioxidants and antimicrobials. The polymer “carrier” can physically capture the active component, preserving its biological stability, or the component can be incorporated chemically into a polymer, to be released when it reacts with water. (These are the same technologies used in pharmaceuticals to enable controlled release of medicines.) 
  • Salicylic acid, used in over-the-counter anti-acne products, is an example of a personal care product component that can be delivered this way. Another use is encapsulation of ingredients such as vitamins and peptides so that they are able to work when applied to hair and skin during use.

Moisturizers & Conditioners 

  • In cosmetics, hyaluronic acid is used as a moisturizer because it has the main property of retaining water on the skin surface. It is also used to modify the viscosity of formula and create a nice sensory feeling upon application on skin. (Hyaluronic acid is also used in aesthetic medicine in sub-dermal injections to fill wrinkles.) 
  • Conditioning polymers deposit, adhere, or absorb into the proteins of the skin and hair. They improve skin feel and hair manageability, reduce static and make the skin and hair softer and smoother. Examples include polyquaternium-6, polyquaternium-7, and polyquaternium-11.
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