Controlled stereochemistry of polyamides derived fromcis/trans-1,4-cyclohexanedicarboxylic acid

Abstract

A series of copolyamides 12.y was synthesized either with y = 6, or 1,4‐cyclohexanedicarboxylic acid (1,4‐CHDA) residue, or a mixture of both. The influence of the synthetic route of 1,4‐CHDA containing polyamides on the obtained cis–trans ratio of the incorporated 1,4‐CHDA was investigated. The use of acid chlorides provided a synthetic route with full control of the cis–trans ratio of the 1,4‐CHDA residue during synthesis, whereas synthesis at elevated pressure and temperature caused isomerization. The content and cis–trans ratio of 1,4‐CHDA in the copolyamides were determined by solution 13C NMR spectroscopy. Increasing the degree of partial substitution of the adipic acid by 1,4‐CHDA resulted in an increase in Tm, even for low molar precentages of 1,4‐CHDA. This phenomenon points to isomorphous crystallization of both the 12.6 and 12.CHDA repeating units. The mps of the synthesized polyamides were independent of the initial cis–trans ratio of 1,4‐CHDA, provided that the samples were annealed at 300 °C before DSC analysis. The polyamides exhibited a different melting pattern depending on the 1,4‐CHDA content. At a low a 1,4‐CHDA content a net exothermic recrystallization occurred during melting, whereas at higher contents of 1,4‐CHDA this recrystallization occurs to a lesser extent, and two separate melting areas are observed. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 833–840, 2001

Polybutylene terephthalate modified with dimer acid methyl ester derived from fatty acid methyl esters and its use as a hot‐melt adhesive

“…Generally, PBT is reported to be a semicrystalline polymer with a T g of 40~60 C, T m of 220~230 C, and ΔH f of 145 J g −1. 28,33 This conclusion is also supported by the decreasing L n T(I)-B and increasing random sequences in the copolymers, determined from the 1 H NMR results. The T m values showed a similar trend to that of T g and was observed from the DSC curve upon further heating.…”

Stereochemistry of Polymerization

“…For example, neither the ester nor the amide groups in polyesters and polyamides, respectively, possess stereocenters. Stereoregular polymers are possible when there is a chiral stereocenter in the monomer(s) [Oishi and Kawakami, 2000;Orgueira and Varela, 2001;Vanhaecht et al, 2001]. An example would be the polymerization of (R) or (S)-H 2 NCHRCOOH.…”

Ageing of PCCD aliphatic polyesters: Effect of stereochemistry and ionic chain terminals

“…Therefore, the thermal behaviour of PCCD is strongly influenced by the cis/trans isomeric ratio [18][19][20][21][22][23][24][25]. In particular, in a previous study, the authors demonstrated that the crystallinity is modulated by the molar percentage of trans cycloaliphatic units in PCCD samples prepared from CHDM (with 66 mol% of trans isomer) and DMCD (with trans isomer content variable from 24 to 97 mol%).…”