Long-Spaced Polyamides: Elucidating the Gap between Polyethylene Crystallinity and Hydrogen Bonding

Abstract

Aliphatic polyamides with so far inaccessibly low amide contents were prepared by acyclic diene metathesis (ADMET) copolymerization of N-(undec-10-en-1-yl)undec-10-enamide (1) and undeca-1,10-diene (2) applying different Grubbs and Hoveyda−Grubbs type olefin metathesis catalyst precursors, followed by exhaustive postpolymerization hydrogenation to yield saturated copolymers. These polyamides, containing between 1.0 and ca. 50.5 amide groups per 1000 methylene units, fill the gap between polyamides from classical polymerization approaches, like polycondensation of diamines with diacids, and linear polyethylene. With reduced amide concentrations the melting points of polyamides converge toward polyethylene, passing through a distinct melting point minimum observed around 110°C for polyamides with ca. 35 amide groups per 1000 methylene units. The minimum goes in hand with a change in the crystal structure related to the different ratios of intersegment interactions from hydrogen bonding and nonpolar van der Waals forces depending on the amide group content in the crystalline state. Furthermore, the influence of hydrogen bonds between amide and ester groups has been quantified for polyesteramides with various amide/ester ratios, prepared by ADMET copolymerization of N-(undec-10-en-1-yl)undec-10-enamide (1) with undec-10-en-1-yl undec-10-enoate (3) and postpolymerization hydrogenation.

Long-Chain Polyorthoesters as Degradable Polyethylene Mimics

“…In most cases, a glass transition point was either not detectable or outside the measured range (minimum −100 °C). While the non-hydrogenated polymers are either amorphous or show a T m below room temperature, the hydrogenated polymers have T m up to 117 °C for poly( 2 ) 1 - co -COD 9 , which is similar to completely linear PE with 134 °C 6 (cf. Figure 3C shows the DSC thermogram of poly( 3 ) 1 - co -COD 9 with T m = 109 °C).…”

Redefining polyamide property profiles via renewable long-chain aliphatic segments: Towards impact resistance and low water absorption

“…where V is the volume of the specimen (cm 3 ), m1 and m2 are the mass of the specimen (g) in air and water, respectively, and ρH2O is the density of water (1 g•cm 3 ). The mass of the object in air was then divided by this calculated volume to yield the density.…”

“…These PAs possess a range of attractive properties, including high mechanical strength, good solvent stability/resistance, lower melting temperatures and low moisture absorption 3,4 . In particular, reduced moisture absorption gives long-chain PAs a competitive edge over their shorter-chain counterparts, such as PA 6 and PA 6,6.…”

Plant‐Oil‐Based Polyamides and Polyurethanes: Toward Sustainable Nitrogen‐Containing Thermoplastic Materials

“…Using the same C20 diester monomer, also renewable polyesteramides with adjustable thermal properties were described . An even longer amide spacing in aliphatic polyamides was achieved by the copolymerization of the renewable N ‐(undec‐10‐en‐1‐yl)undec‐10‐enamide with undeca‐1,10‐diene in different ratios via ADMET polymerization and hydrogenation, leading to polyamides containing between 1 and 50 amide groups per 1000 methylene units . The authors observed that the melting points of these polyamides converged toward one of polyethylene the lower the amide group content got.…”