Biobased building blocks for the rational design of renewable block polymers Angela L. Holmberg, a Kaleigh H. Reno, ab Richard P. Wool ab and Thomas H. Epps, III * a Block polymers (BPs) derived from biomass (biobased) are necessary components of a sustainable future that relies minimally on petroleum-based plastics for applications ranging from thermoplastic elastomers and pressure-sensitive adhesives to blend compatibilizers. To facilitate their adoption, renewable BPs must be affordable, durable, processable, versatile, and reasonably benign. Their desirability further depends on the relative sustainability of the renewable resources and the methods employed in the monomer and polymer syntheses. Various strategies allow these BPs' characteristics to be tuned and enhanced for commercial applications, and many of these techniques also can be applied to manipulate the wide-ranging mechanical and thermal properties of biobased and self-assembling block polymers. From feedstock to application, this review article highlights promising renewable BPs, plus their material and assembly properties, in support of de novo design strategies that could revolutionize material sustainability. 1. Introduction Renewable polymers, i.e. polymers derived mostly or entirely from biomass (biobased), are assisting global efforts to reduce dependence on petrochemical resources, minimize toxicity, and curtail CO 2 emissions. Moreover, demand for renewable polymers is growing at 19% annually, with global consump- tion expected to reach one million tons by 2017. 1 However, renewable polymers constitute less than 1% of the estimated 300 million ton yearly production of plastic worldwide, 2 leaving ample room for the development of new materials to meet growing demand. Commonly researched renewable plastics include polyurethanes, polyolens, polyesters, and vinyl polymers suitable for wide-ranging applications, such as commodity items (e.g., plasticware, electronics casings, synthetic fabrics, cushioning, adhesives) and tailored materials (e.g., compact discs, screen protectors, biomedical devices, separation membranes). For designer applications, renewable block polymers (BPs) that unite characteristics of two or more chemically distinct polymers into a single material via covalent bonds are ideal Angela L. Holmberg earned bachelor's degrees in chemical engineering (B.Ch.E.) and chemistry (B.S.) from the University of Minnesota, Twin Cities in 2010. She is pursuing her doctoral studies at the University of Delaware under the supervision of Prof. Thomas H. Epps, III. Her research focuses on the design, synthesis, and characterization of sustain- able, nanostructured block polymers. Her work has been recognized by the ACS Green Chemistry Institute with a 2013 Ciba Travel Award and a 2013 NSF Travel Scholarship. Kaleigh H. Reno received her bachelor's degree in chemical engineering from the University of South Carolina in 2012 and is pursuing her doctoral degree at the University of Delaware, where she is co-advised by Prof. Richard P. Wool and Prof. Thomas H. Epps, III. Her research utilizes renewable materials, specically lignin, in the design and synthesis of sustainable alternatives to commodity petroleum-derived aromatic monomers for high- performance thermoplastic and thermoset applications. a Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA. E-mail: thepps@udel.edu b Center for Composite Materials, University of Delaware, Newark, Delaware 19716, USA Cite this: Soft Matter, 2014, 10, 7405 Received 6th June 2014 Accepted 29th July 2014 DOI: 10.1039/c4sm01220h www.rsc.org/softmatter This journal is © The Royal Society of Chemistry 2014 Soft Matter, 2014, 10, 7405–7424 | 7405 Soft Matter REVIEW