Technology

Polnox's high performance antioxidant technology was initially developed by Dr. Cholli and his team at the Center of Advanced Materials, University of Massachusetts Lowell . The technology employs a one step, environmentally benign method involving biocatalysts, and natural and synthetic materials. Dr. Cholli's antioxidant technology has significantly improved material protection, due to enhanced antioxidant activity, higher thermal stability and low to no diffusion. Industry standard tests have been conducted at independent laboratories to compare Polnox's novel antioxidants versus current antioxidants in a variety of materials

The biocatalytic process used by Polnox is a new biotechnology-based methodology for the synthesis of macromolecular antioxidants. To date, Polnox has attracted significant commercial business interest due to its environmental compatibility involving unsurpassed ease of use one-step synthesis, stability, and processability. Polnox's Green Chemistry approach is a promising efficient alternative to traditional synthetic routes for synthesis of macromolecular antioxidants with enhanced antioxidant activity and improved thermal stability.

The catalytic cycle for some of the catalysts used in the Polnox processes involves a two-electron oxidation step and two one-electron reduction steps, resulting in the formation of radicals on the starting molecules. These free radicals then undergo coupling to produce dimer, and successive steps of oxidation, and subsequent radical-radical couplings produce macromolecular antioxidants. These macromolecular antioxidants have been characterized using analytical and spectroscopic techniques including NMR, MALDI, FTIR, UV/Visible, HPLC, DSC, TGA, GPC and other techniques.

Polnox technology is applicable to multiple business sectors. The major business sectors include plastics and elastomers, lubricants, fuel, oil, cooking oil, food and food packaging, beverage and other industries.

Polnox to date has developed seven core macromolecular antioxidants to meet each sector's specific needs.

The antioxidant activities (measured as AA%) of starting materials and macromolecular antioxidants are evaluated according to the method reported in Food Chemistry 73, 285 (2001) and Phytochemistry, 37, 1585 (1994). A typical antioxidant activity measurement profile based on the assay for the current commercial AO and Polnox's macromolecular AO are compared. Antioxidant activity of antioxidants at 100 ppm concentration were measured by the bleaching of the - carotene system. The mechanism of bleaching of -carotene is a free-radical mediated phenomenon. In this model system, -carotene undergoes rapid discoloration in the absence of an antioxidant. The linoleic acid free radical, formed upon the abstraction of a hydrogen atom from its diallylic methylene groups, attacks the highly unsaturated -carotene molecules. As -carotene molecules lose their double bonds by oxidation, the compound loses its chromophore and characteristic orange color. The amount of sample used for the analysis is the same for both monomers and macromolecular AOs. The percentage of increased antioxidant activity ranged between 30% for PNX AO1 to 1450% for PNX AO3 as compared to the corresponding current commercial antioxidants. Polnox's enhanced antioxidant performance is most probably due to the collective ability of multiple oxidizable sites on these macromolecules to react rapidly to the oxidation-causing event as well as due to their molecular weight. In addition, the radicals that are generated in the macromolecules are likely to be more stable compared to the current commercial and smaller antioxidant radicals. The performance of these PNX AOs in consumer products has also been evaluated using industry standard tests such as ASTM, AOCS and other methods show significantly improved activities and performances.

The performance of macromolecular antioxidants in a wide range of materials shows significantly higher oxidative resistance. These molecules also have higher thermal stability. The enhanced activity of Polnox PNX AO, for example, suggests that one could use three times less the amount of antioxidant used today in polyolefin such as PE or PP without sacrificing their performance. Another benefit of using lower amount of antioxidants is that it minimizes the unwanted inter chemical transformation reactions such as discoloring. Discoloring of the finished product due to inter chemical transformation reactions is one of the major concerns in the plastics industry. This is often referred to as 'phenolic yellowing or pinking'. This problem is very serious in cases where chemically transformed molecules tend to come to the surface as a result of migration. The diffusion of such molecules scales approximately as the inverse of the cube root of the molecular weight. High molecular weight, macromolecular antioxidants developed by Polnox possessing significantly improved thermal stability along with higher antioxidant activity may assist in solving this serious industrial problem in plastics.

In the case of oils and lubricants, the performance of PNX antioxidant is significantly better compared to presently used antioxidants. The Oxidation Stability Index (OSI) (AOCS Cd-12b-92 method of American Oil Chemists Association), Total Acid Number (TCN) test and Free Fatty Acid (FFA) test on soybean oil samples containing TBHQ and Polnox AOs which are heated at 190 °C for different lengths of time show a superior performance of Polnox PNX AOs compared to currently used AO.

Free fatty acid (FFA) content in oil is dependent on the quality of oil. They are formed due to breakdown of oil molecules, triglycerides into its components (fatty acids and glycerol). Antioxidants help to preserve the quality of oil by retarding the oxidative degradation of oil in the presence of heat, light and oxygen thus lowering the formation of free fatty acid. It is known that high free fatty acids levels may not be good for human health. There is evidence that they may cause a number of problems if the free fatty acids content is too high. Thus antioxidants that lower the formation of these free fatty acids by preserving the oil is beneficial to human health. The plot shows that Polnox AO has a superior performance in protecting the oil from breaking down into free fatty acids as a result of the oxidation process at frying temperatures.

Thermal stability of antioxidants plays a key role in their ability to protect materials. For example, many of the antioxidants that are used in food applications are prone to volatilize or degrade themselves at temperatures ca. 200 C. This is not the case with Polnox antioxidants, which are stable even at 375 C. This is one of the main reasons why the quality of oil is excellent in cases where Polnox antioxidants are used. In addition, Polnox macromolecular antioxidants are equally effective in gasoline oil and lubricants. In summary, macromolecular antioxidants developed by Dr. Cholli and his team at Polnox is a disruptive technology and effective in many materials that have been tested so date. Antioxidants created using this innovative technology are cost effective and have a superior price-performance ratio.