Structural and morphological investigations of nylon 8 chain-folded lamellar crystals

Structure and morphology of nylon 2 4 lamellar crystals: Comparison with polypeptides and relationship with other nylons

“…We believe our generalized model for even and even-even nylons 27,28 is also compatible with the reported experimental data.…”

“…25 It has been argued that these changes are associated with a continuous decrease in the population of intrasheet hydrogen bonds as a proportion transfer to form intersheet hydrogen bonds. 5,27,28 Indeed, the Brill model, 25 at the Brill temperature (T B ), is for a hexagonal (trigonal) arrangement of interchain hydrogen bonds. For example, as the temperature is raised in nylon 6 6, we envision a progressive transfer from a structure with wholly intrasheet hydrogen bonds to one with populations in three trigonal directions; the process starting below the T B and being completed above T B .…”

“…It is known that a pseudo-hexagonal phase 25,2,27,28 exists for nylons at higher temperatures (i.e., above 12,14 (d) The ␥-turn in the chain-folded ap␤-sheet for polyglycine; it contains two amide units. [12][13][14][15] the Brill temperature 24 ) and models have been proposed in which the interchain hydrogen bonds are distributed with hexagonal symmetry in the three trigonal directions orthogonal to the chain axes, and the alkane segments are mobile.…”

Discovery in nylon-8 chain-folded lamellar crystals of new structure??-structure?with progressive intersheet shear along the chain axis

“…The structure is analogous to the ␣-structure originally proposed by Holmes et al 6 for nylon-6. Structural and morphological studies on solution-grown nylon-8 chain-folded lamellae were reported by Atkins et al 9 The electron diffraction results confirmed that the lathelike crystals prepared by seeding in 1,4-butanediol at 140°C, and isothermally crystallized for 36 h at 125°C (T c ), were in the ␣-structure.…”

Synthesis, structure and crystal morphology of nylon 16

“…According to all expectations 16) chain folding in nylon 16 must occur through the long flexible polymethylene segment. A comparison of the length of the repeating unit of nylon (2.08 nm) with the lamellar thickness (5.7 nm) leads to infer that two residues might be accommodated within the core and a third one is used for the folding on each crystal surface, so that three amide groups are contained in the crystalline core of the lamellar structure.…”