CAREER:Shape Memory Polymers as Biomaterial

Non-technical Description:

You may have heard about heat shrink tubing. These shrinkable plastic tubes are typically used to insulate unprotected wires to protect them against abrasion and other environmental impacts, such as dust and moisture. These tubes are made of so-called shape memory polymers and can change their shape after applying a specific stimulus, such as temperature.

What if these materials could be used to seal body parts and organs (such as the intestines or vasculature) after surgery or injury? Unfortunately, the conditions for the shrinking of conventional heat shrink tubing are not suitable for biomedical applications, as those conditions far exceed body temperature and would damage human tissues and injure the patient.

However, a heat shrink tube that responds to bodily conditions would enable various medical applications and advance health care. This is why this NSF grant aims to translate heat shrink tubing to the biomedical field to seal biological tissues. To realize the biomedical version of this technology, a shape memory polymer that (1) is biocompatible, (2) shrinks within minutes under physiological conditions without the need for excessive application of heat, and (3) is biodegradable will be developed and investigated.

This project also includes educational activities designed to raise excitement, awareness, and interest in the emerging field of smart polymeric biomaterials. This excitement will be achieved by encouraging underrepresented minorities and women to pursue careers in biomedical engineering through a gender- and ethnicity-matched mentor-mentee program.

To excite non-scientists about polymer research, a 'science slam' event at local venues will be implemented. Students and faculty members from UNT will present their research in lay terms and in a funny way at these events. Technical Description:

This CAREER project aims to elucidate the underlying mechanism of the plasticization-induced shape memory effect of thiol-ene based polymers. The model application for this material will be a heat shrink tubing that can shrink at bodily conditions (37° C and simulated body fluids) and can be used to seal colonic anastomosis. The specific three aims are to (1) Systematically investigate the effect of crosslink-density and chain extender length on the plasticization-induced shape memory effect of thiol-ene based polymers.

Mechanical and thermomechanical measurements inside simulated body fluids will be used to assess shape memory properties and structure-property relationships. (2) Understand the relationship between material thickness, degree of shape-programming, and radial recovery forces of tube-shaped SMPs to determine optimal design parameters for sufficient shape recovery using the heat shrink tube model. (3) Demonstrate the functionality of a biomedical heat shrink tube that utilizes the plasticization-induced shape recovery through an ex vivo colon anastomosis model and quantify mechanical and sealing properties. The proposed research will advance science by filling the gap in the structure-property relationship of thiol-ene based SMPs that utilize plasticization for their shape recovery, which is essential for designing future devices.

In addition, this innovative biomaterial will allow the broader research community to develop novel biomedical devices tailored to specific tissues and applications. Educational and outreach activities will be implemented to raise excitement, awareness, and interest in the emerging field of smart polymeric biomaterials. These will include a gender- and ethnicity-matched mentor-mentee program, training students from underrepresented groups in the PI's laboratory, incorporating research discoveries into coursework, and communicating research to the general public at local science slam events.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.