Stimuli-Responsive Polymers. VIII. Polyesters and Poly(ester amides) Containing Azobenzene and Chiral Binaphthylene Segments: Highly Adaptive Materials Endowed with Light-, Heat-, and Solvent-Regulated Optical Rotatory Power GARY D. JAYCOX Experimental Station, Biochemical Science and Engineering, DuPont Central Research and Development, Wilmington, Delaware 19880-0328 Received 14 September 2005; accepted 15 September 2005 DOI: 10.1002/pola.21149 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Azobenzene-modified polyesters and poly(ester amide)s fitted with chiral, atropisomeric binaphthylene segments were prepared by a series of low-temperature polycondensation reactions carried out in polar solvent media. When compared with their polyaramide counterparts studied earlier, these materials had significantly improved solubility behaviors and were readily dissolved by a wide range of organic solvents. In solution, each of these constructs underwent photoinduced oscillations in optical rotatory power when subjected to multiple UV-light/visible-light illumination cycles that drove trans$cis isomerization reactions along their polymer chains. Light- regulated chiroptical perturbations were dependent on polymer backbone structures and were further modulated by well-coordinated temperature fluctuations and by the nature of the solvent medium employed. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 207–218, 2006 Keywords: atropisomeric monomers; azo polymers; chiral; photophysics; stimuli- sensitive polymers INTRODUCTION Macromolecules endowed with light-responsive geometries constitute a unique and rapidly ex- panding class of materials. Polymers falling within this category are broadly relevant to a variety of emerging technologies, including novel sensory devices and optical recording media. Properly designed, these systems can also serve as biomi- metic analogues that allow for an improved un- derstanding of vital photoprocesses that are oper- ative in many living organisms. Azobenzene-modified polyaramides fitted with chiral, atropisomeric binaphthylene segments have been extensively studied in this laboratory. 1–7 As designed, these materials undergo photoinduced oscillations in optical rotatory power when sub- jected to multiple UV-light/visible-light illumina- tion cycles that drive trans$cis isomerization reactions along the polymer chain. Chiroptical perturbations can be dramatic, with specific rota- tions shifting by several orders of magnitude 2–5 or even inverting to the opposite sign. 6,7 As we This article is dedicated to the late Professor Walter H. Stockmayer of Dartmouth College, who helped make polymer science look easy for the rest of us. This report is DuPont Contribution No. 8596. Correspondence to: G. D. Jaycox (E-mail: gary.d.jaycox@usa. dupont.com) Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 44, 207–218 (2006) V V C 2005 Wiley Periodicals, Inc. 207