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A facile route to ketene-functionalized polymers for general materials applications
Leibfarth, Frank A.,Kang, Minhyuk,Ham, Myungsoo,Kim, Joohee,Campos, Luis M.,Gupta, Nalini,Moon, Bongjin,Hawker, Craig J. Nature Publishing Group 2010 Nature chemistry Vol.2 No.3
Function matters in materials science, and methodologies that provide paths to multiple functionality in a single step are to be prized. Therefore, we introduce a robust and efficient strategy for exploiting the versatile reactivity of ketenes in polymer chemistry. New monomers for both radical and ring-opening metathesis polymerization have been developed, which take advantage of Meldrum's acid as both a synthetic building block and a thermolytic precursor to dialkyl ketenes. The ketene-functionalized polymers are directly detected by their characteristic infrared absorption and are found to be stable under ambient conditions. The inherent ability of ketenes to provide crosslinking via dimerization and to act as reactive chemical handles via addition, provides simple methodology for application in complex materials challenges. Such versatile characteristics are illustrated by covalently attaching and patterning a dye through microcontact printing. The strategy highlights the significant opportunities afforded by the traditionally neglected ketene functional group in polymer chemistry.
Jung, Hyunjung,Leibfarth, Frank A.,Woo, Sanghoon,Lee, Sumi,Kang, Minhyuk,Moon, Bongjin,Hawker, Craig J.,Bang, Joona WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.12
<P><B>Abstract</B></P><P>Balancing the interfacial interactions between a polymer and substrate is one of the most commonly employed methods to ensure the vertical orientation of nanodomains in block copolymer lithography. Although a number of technologies have been developed to meet this challenge, there remains a need for a universal solution for surface neutralization that combines simple synthesis, fast processing times, generality toward substrate, low density of film defects, and good surface adhesion. The chemistry of ketenes, which combines highly efficient polymer crosslinking through dimerization and surface adhesion through reaction with the substrate, is shown to be well suited to the challenge. The versatile chemistry of ketenes are accessed through the post‐polymerization of Meldrum's acid, which can be easily incorporated into copolymers through controlled radical polymerization processes. Further, the Meldrum's acid monomer is synthesized on a large scale in one step without the need for chromatography. Processing times of seconds, low defect density, simple synthetic procedures, and good substrate adhesion make these materials attractive as robust block copolymer neutralization layers.</P>