Heat capacity of spider silk-like block copolymers

Wenwen Huang, Sreevidhya Krishnaji, Xiao Hu, David Kaplan, Peggy Cebe

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

We synthesized and characterized a new family of diblock copolymers based on the amino acid sequences of Nephila clavipes major ampulate dragline spider silk, having the form HABn and HBAn (n = 1-3), comprising an alanine-rich hydrophobic block, A, a glycine-rich hydrophilic block, B, and a histidine tag, H. The reversing heat capacities, Cp(T), for temperatures below and above the glass transition, Tg, were measured by temperature modulated differential scanning calorimetry. For the solid state, we then calculated the heat capacities of our novel block copolymers based on the vibrational motions of the constituent poly(amino acid)s, whose heat capacities are known or can be estimated from the ATHAS Data Bank. For the liquid state, the heat capacity was estimated by using the rotational and translational motions in the polymer chain. Excellent agreement was found between the measured and calculated values of the heat capacity, showing that this method can serve as a standard by which to assess the Cp for other biologically inspired block copolymers. The fraction of β sheet crystallinity of spider silk block copolymers was also determined by using the predicted Cp, and was verified by wide-angle X-ray diffraction and Fourier transform infrared spectroscopy. The glass transition temperatures of spider silk block copolymer were fitted by Kwei's equation and the results indicate that attractive interaction exists between the A-block and the B-block.

Original languageEnglish (US)
Pages (from-to)5299-5309
Number of pages11
JournalMacromolecules
Volume44
Issue number13
DOIs
StatePublished - Jul 12 2011

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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