Synthesis and rheological behavior of poly(1,2-butylene oxide) based supramolecular architectures

Abstract

In this work we present the synthesis of poly(1,2-butylene oxide) (PBO) functionalized with the complementary hydrogen bond forming groups 2,4-diaminotriazine (DAT) and thymine. PBO is a rubbery polymer. Due to its semi-polar nature PBO is expected to suppresses non-directed cluster formation of the supramolecular groups but not influence their directed interactions. For the synthesis of backbone functionalized polymers we developed a procedure which allowed randomly copolymerizing BO with 1,2-epoxy-7-octene using anionic ring opening polymerization with potassium tert-butanolate as initiator. The vinyl groups were converted to OH-groups by oxidation. In addition, PBO with one alcoholic end group was obtained by homopolymerization of BO. For the variant with OH-groups at both chain ends a procedure was developed which was based on the cleavage of the tert-butyl initiator group. In all the polymers the alcohol groups were basically quantitatively transformed into NH 2 -groups.DAT and thymine functionalities were attached to the NH 2 -groups again in almost quantitative conversion. All reaction steps were monitored by 1 H-NMR using pyridine-d 5 as solvent. This method allowed determining the conversions of the different synthesis steps with high precision. The materials were examined in linear rheology in order to study the effect of the hydrogen-bonds on the dynamics of the resulting supramolecular structures. The results corroborate the exclusive existence of directed interactions between the supramolecular groups.

Supramolecular Dimerization in a Polymer Melt from Small-Angle X-ray Scattering and Rheology: A Miscible Model System

“…An increased compatibility of thy and DAT was also achieved in the literature with poly(butyl acrylate) (PBA) as the matrix [19]. However, the strong rise in the T g by roughly 30 • C upon functionalization of the PBA polymer may be an indication for strong local effects as well, and it contrasts with the observations for the present PBO polymer [42]. In addition, PBO is a particularly interesting intermediate polar polymer because of its low T g (−65 • C) and an entanglement molecular weight around 8000 g/mol.…”

“…In addition, PBO is a particularly interesting intermediate polar polymer because of its low T g (−65 • C) and an entanglement molecular weight around 8000 g/mol. Both are very similar to the apolar polyisoprene (PI) or natural rubber (NR) elastomers [42]. PBA, though with comparably low T g , on the other hand possesses an entanglement molecular weight of about 30,000 g/mol and does not show valuable elastomeric properties on its own.…”

“…All poly(butylene oxide) (PBO) polymers were prepared by anionic ring-opening polymerization with subsequent chemical modification. The specific synthetic details and characterization by size-exclusion chromatography (SEC) (Polymer Laboratories, PL 220, Salop, UK) have been published elsewhere [42] and are repeated in short in Table 1. All samples were stored at −20 • C before use.…”

Hydrogen Bonding in a Reversible Comb Polymer Architecture: A Microscopic and Macroscopic Investigation

“…As reported in a previous study no sign of self -association was revealed for the thymine functionalized backbone. Instead, a more pronounced effect of the functionalization with DAT groups was observed for the short chains 9 .…”

“…In semi-functionalized blends, d-PBO thy-80k was used instead of pure d-PBO 80k as it does not show any signs of homo-association. 9 In the first case the blend of semifunctionalized components (red below) shows a close to Rouse-like behavior at long times typical of a non-entangled polymer system. The Rouse-like behavior at intermediate frequency…”