Multiblock Polymers: Panacea or Pandora's Box?

Frank Bates of University of Minnesota

Synthetic polymers impact nearly every segment of the chemical engineering profession with applications in commodity and value added plastics and elastomers, medical and separation technologies, the microelectronics industry, and a host of products that facilitate energy conversion and storage. Recent advances in polymer chemistry provide economically tractable strategies for combining two or more types of macromolecules into multiblock polymers capable of generating almost any imaginable nanoscale structure endowed with remarkable properties. However, increasing the number (n) and type (k) of discrete blocks leads to an explosion in sequencing possibilities, each capable of producing myriad morphologies, similar to the dilemma faced when designing new proteins for biological application. For example, just three sequences are possible with n = 3 and k = 3 (ABC, ACB and BAC) while n = 4 and k = 3 results in 9 distinct linear combinations. A modest increase in molecular complexity, n = 6 and k = 4, results in 300 unique possibilities! What engineering strategies are available for selecting among the multitude of choices? This lecture outlines the basic principles underpinning multiblock polymer science and engineering including modern synthetic approaches, how molecular architecture influences structure and properties, contemporary characterizations methods, and the current state of predictive statistical theories. Several commercially successful examples will be used to highlight the unparalleled opportunities for creating new materials and products presented by this emerging class of polymers.