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Silk: fibers, films, and compositesdtypes, processing, structure, and mechanics 161

(a) 1668 (b)
1645
Fresh silk
1666

1687
Type III

Raman intensity Dried gland 1672 Type II

1688
1645 1688

1659
Fresh gland
Type I
1681
α-helix
β-sheets

1500 1550 1600 1650 1700 1600 1650 1700 1750
Wavenumber / cm –1 Wavenumber / cm –1
Figure 5.13 (a) Comparison of the Raman signatures in the Amide I (aec) and NeH/H 2 O
stretching regions (c) for the fresh (quasi in vivo) and dried Bombyx mori gland (a), for a fiber as
(forced) spun by a living B. mori silkmoth (fresh silk) and for different fibers of Type I, II, and
III (see Fig. 5.3(a)). (c) (1) The huge intensity decrease of the water signature from quasi in vivo
gland measurement to fresh and degummed fiber; (2) the comparison of the Amide I bandwidth
for degummed fiber and for different regenerated film; (3) detail on the band narrowing at 10K
of the water stretching mode; note the bandwidth and position of the NH mode does not change.
(a and b) After Dinh HM: Raman/IR study of the variability of proteic fibres: relationship
between local structure, treatments and (nano)mechanical properties of silk fibres and films
(Ph.D. dissertation), December 14, 2010, Université Pierre et Marie Curie (Paris 6). http://www.
ladir.cnrs.fr/pages/colomban/Manh-Thesis.pdf and (c) After Colomban P, Dinh HM: Origin of
the variability of the mechanical properties of silk fibres: II, the nanomechanics of single
silkworm and spider fibres, J Raman Spectrosc 43:1035e1041, 2012.

Percot et al. (2014). The structural differences are obvious but limited, especially with
the shift of the main component wave number and the change of the relative intensity.
The different Raman (and also infrared) components of the Amide I band (and/or
characteristic ratio in between) have been assigned to the different chain conformations