Soft PVC plastic materials, found notably in blood bags and surgical tubing, are crucial to a number of medical procedures. They are typically formulated with a high percentage of phthalate esters which impart flexibility, but migrate extensively from the plastic, exposing the patient to potential reproductive hazards. These materials have recently been banned from toys, and the FDA has recommended that they be replaced in sensitive medical applications, largely due to concern over risks to reproductive development in human males. Adequate, safe replacements have not yet been identified. Several alternatives have been investigated, but most are small molecules which migrate from bulk plastics, and whose toxicology in humans is unknown. Promising results have been obtained with macromolecules (branched polyesters), though current candidates readily decompose to small molecules which similarly leach out and expose the patient to unknown risks, accompanied by loss of plasticizer efficiency. These studies will investigate a class of copolymers with pendant ester functionality which will provide requisite physical properties to PVC blends for sensitive applications, but which do not migrate, and further, do no degrade to oligomers and monomers of unknown toxicology. Transition metal catalysis will allow discrete tailoring of materials properties for definitive determination of structure/property relationships. The long-term objective of the present work is to understand how macromolecular architecture and functionality may be optimized to provide high-performance biocompatible materials for medical applications which avoid the risks associated with current products. Studies will determine which structural features of polymers impart maximal resistance to migration while providing flexible blends.
The Specific Aims are: 1) Synthesize a series of copolymers with pendant ester functionality, with systematic variation of design elements for plasticization of PVC 2) Determine polymer structure-property relationships to prevent plasticizer migration from PVC 3) Determine effects of weight, branching, and ester content on plasticizer performance.
The impact of the proposed research on public health is considerable. These studies have the potential to provide replacements for substances of known reproductive toxicity to which all humans are exposed, many at elevated levels in medical procedures. The development of non-migrating plasticizers will allow the continued necessary use of flexible plastics materials without exposing patients to reproductive health hazards.