Chlorine Dioxide
Releasing Materials
Materials & Bioengineering

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image of CLARA extruded

CLARA (1-10 wt% loading) extruded into polyethylene films

image of Controlled release of ClO2 gas

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Controlled release of ClO2 gas from film composite. Release coincides with exposure to fluorescent light.

image of Extrusion of moisture activating melt processable resin

Extrusion of moisture activating melt-processable resin

Chlorine dioxide, a strong oxidizing agent, has been used to replace other less safe and environmentally unfriendly compounds, such as chlorine or hypochlorite, in large-scale water treatment and pulp bleaching facilities.

There are many positive attributes for the use of chlorine dioxide that include efficacy against a broad spectrum of microbes, dissipating quickly in the environment leaving only low levels of chloride residue, and currently has multiple EPA and FDA registrations.

The difficulty in applying chlorine dioxide, as either solution or a gas, is that it must be generated at site and cannot be stored as a solution without being stabilized for long periods of time or compressed as a gas.

Southwest Research Institute (SwRI) has overcome this challenge by developing two novel technologies that can be fabricated into materials designed to release ClO2 upon demand. These technologies revolve around a Chlorine dioxide Light Activated Releasing Additive (CLARA) and a moisture activating, chlorine dioxide releasing melt-processable resin. While developing these two systems, SwRI has accumulated more than two decades of experience in formulating ClO2 releasing materials. Relevant Patents and Patent Applications include US5360609 (1994), US5631300 (1997), US5707739 (1998), US5965264 (1999), US6277408 (2001), US7273567 (2007), US Pat. Application: 0131395 (2008).

CLARA Attributes

  • Produced by a spray drying method
  • Ionically bound powder with particle size of 1-30 microns
  • Processed into polymers as an additive or into a masterbatch
    • Method: extrusion, blow molding, film casting, plastisol, and solution casting types: PE, EVA, PVC, PCL, etc.

Moisture Activating Melt-Processable Resin Attributes

  • Produced by extrusion blending of an A/B masterbatch
  • ClO2 release regulated by moisture uptake
  • Moisture uptake regulated by formulation of hydrophilic/hydrophobic compounds
  • Processed into polymers as a laminate or sticker
    • Method: extrusion, blow molding, film casting

SwRI Laboratory Scale Extrusion Capabilities

  • Brabender single/twin screw extruder/preparatory mixer
    • ~1 kg batch sizes
    • Capillary, film, blow molding, mixing
    • Cooling bath and pelletizer
  • Haake Minilab twin screw extruder
    • ~2-5 g batches
    • Capillary extrusion
    • Drug formulation

Related Terminology

adaptive materials  •  autonomic materials  •  hybrid materials  •  nanomaterials  •  materials testing  •  materials characterization  •  electrophoretic deposition  •  biomaterial  •  medical device  •  biosensors  •  chlorine dioxide  •  nanoparticles  •  encapsulation  •  drug delivery  •  control release  •  tissue engineering  •  regenerative medicine  •  wound care  •  wound dressing  •  surface coating  •  scaffolds  •  bioreactor  •  perfusion system  •  ISO 13485

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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 9 technical divisions.