Tuning layered superstructures in precision polymers

Abstract

An approach to influence and control layered superstructures by varying the methylene sequence length between two consecutive functional groups in linear precision polymers containing 2,6-diaminopyridine (DAP) groups is presented. Layered superstructures with repeating units involving three monomeric units along the chain direction with very high coherence lengths upto 110 nm are observed in case of shorter alkyl segments, (16 and 18 CH 2 units), while more conventional layer superstructures incorporating only one monomer are found for related polymers with 20 CH 2 units per methylene sequence. A building block model explaining the unusually large periodicity of three monomeric units is proposed wherein layers containing crystalline or amorphous methylene sequences occur in different combinations. Occurrence of different layered structures depending on crystallization conditions, methylene sequence length as well as functional group type is explained by a competition of H-interactions between the DAP groups and the van der Waal forces between the hydrophobic methylene groups.

Secondary Structures in Synthetic Poly(Amino Acids): Homo‐ and Copolymers of Poly(Aib), Poly(Glu), and Poly(Asp)

“…x x [140] ; IR-analysis of orientated films; 𝛼 l -to 𝜔-helix conversion upon heating [141] ; solid films cast from CHCl x x [138] ; films with different M n cast from CHCl 3 with various evaporation rate; IRand DSC-measurements; 𝛼 l -to 𝛼 r -helix conversion for low M n when slow casting; 𝛼to 𝜔-helix to 𝛽-sheet transition with increasing T (Continued) Halle/Leipzig. [48][49][50]52,[54][55][56][58][59][60][61]63,66,67,143] Poly(amino acids) are prepared by ring-opening polymerization of the respective N-carboxy anhydrides, followed by end group modification via the initiator/quencher strategies. Subsequent arrangement into longer chains is accomplished by acyclic diene metathesis (ADMET)-polymerization, followed by hydrogenation of the double bonds, if desired.…”

“…The chain length (and thus the number of repetitive units along the chain) could be precisely adjusted by preparative size-exclusion chromatography (SEC) after ADMET, obtaining fractions with narrowly distributed chain lengths. [48,50] The folding/restraining elements could be freely chosen: I,II) purely geometrical constraints based on Hbonding systems; [52][53][54][55] III) azo-switches reminiscent of artificial 𝛽-turn mimetics; [59][60][61] IV-XI) homo poly(amino acids), primarily based on oligo( Bn Asp/ Bn Glu [48,49] ) and poly(Aib)-peptides; [66,67] and (XI) artificial 𝛽-turn mimetics [56,57] and polyisocyanatehelices. [58] Subsequently, these polymers were studied in view of fibrillation, aggregation, and chirality transfer.…”

“…Synthesis of the hybrid molecules and their biological assembly processes within the CRC TRR 102 @ Halle/Leipzig. [ 48–50,52,54–56,58–61,63,66,67,143 ] Poly(amino acids) are prepared by ring‐opening polymerization of the respective N ‐carboxy anhydrides, followed by end group modification via the initiator/quencher strategies. Subsequent arrangement into longer chains is accomplished by acyclic diene metathesis (ADMET)‐polymerization, followed by hydrogenation of the double bonds, if desired.…”

“…Figure 9. Synthesis of the hybrid molecules and their biological assembly processes within the CRC TRR 102 @ Halle/Leipzig [48][49][50]52,[54][55][56][58][59][60][61]63,66,67,143]. Poly(amino acids) are prepared by ring-opening polymerization of the respective N-carboxy anhydrides, followed by end group modification via the initiator/quencher strategies.…”

Long Chain Polyamides: Influence of Methylene Sequence Length and External Forces on Structural Features

“…The presence of the resulting highly ordered structures was shown in a recent publication. [ 22 ] Such independent packing tendencies are also observed in comb‐like polymers with long alkyl side chains. [ 23–25 ] In these systems, the long‐range ordered layered morphologies are commonly observed as long as one of the subunits (that form the backbone or the side chain) is able to undergo crystallization.…”