Evolution of Microphase Separation with Variations of Segments of Sequence-Controlled Multiblock Copolymers

Abstract

copolymers (MBCPs) are emerging class of materials that are becoming more accessible in recent years. However, to date there is still a lack of fundamental understanding of their physical properties. In particular, the glass transition temperature (Tg) which is known to be affected by the phase separation has not been well characterised experimentally. To this end, we report the first experimental study on the evolution of the Tgs and the corresponding phase separation of linear MBCPs with increasing number of blocks whilst keeping the overall degree of polymerisation (DP) constant (DP = 200). Ethylene glycol methyl ether acrylate (EGMEA) and tert-butyl acrylate (tBA) were chosen as monomers for reversible addition-fragmentation chain transfer polymerization to synthesise MBCPs. We found the Tgs (as measured by Differential Scanning Calorimetry) of EGMEA and tBA segments within the MCBPs to converge with increasing number of blocks and decreasing block length, correlating with the loss of the heterogeneity as observed from Small Angel X-ray Spectroscopy (SAXS) analysis. The Tgs of the multiblock copolymers were also compared to the Tgs of the polymer blends of the corresponding homopolymers, and we found that Tgs of the polymer blends were similar to those of the respective homopolymers, as expected. SAXS experiments further demonstrated microphase separation of multiblock copolymers. This work demonstrates the enormous potential of multiblock architectures to tune the physical properties of synthetic polymers, by changing their glass transition temperature and their morphologies obtained from microphase separation, with domain sizes reaching under 10 nm.

Reverse-phase high performance liquid chromatography (RP-HPLC) as a powerful tool to characterise complex water-soluble copolymer architectures

“…[10][11][12][13] For example, polymer sequence was demonstrated to affect the glass transition temperature of copolymers of ethylene glycol methyl ether acrylate (EGMEA) and tert-butyl acrylate (tBA). 14 In other example, segmentation was also shown to have a dramatic influence on the interaction of copolymers with lipid membranes. 15,16 By varying the monomer distribution along the backbone, Kuroda et al were able to design copolymers that selectively interacted with the membrane of bacteria while presenting relatively low haemolytic profiles.…”

Structural Composition Explains Differences in Stretchability for Compression-Molded Arabinoxylan-Based Thermoplastic Films

“…The presence of dual glass transitions was recorded for AXWB derived thermoplastics from DSC (Figure 2a and Figure 3a (i)). These dual transitions are often evident for thermoplastic polymers suggesting phase separation and were reported for multiblock synthetic polymers, 1,36 conjugated polymers, 37 esterified cellulose, 22 lignin based thermoplastics, 34,38 thermoplastic elastomers (TPE). 39 The first (lower) glass transition (-75 to -48 °C) plausibly originated from the side chain extension by alkoxide chains in the native AX and activated AX [shadowed region annotated as Tg1 in Figure 3a ) and Tg2 ( ) denote the Tgs determined from the above-ambient and sub-ambient endotherm transitions of the second heating DSC curves (Fig.…”

A New Strategy to Synthesize α,ω‐Dihydroxy Multiblock Copolymers via [CpRu(CH3CN)3]PF6/Quinaldic Acid Catalyst

“…Multiblock copolymers (MBCs) containing random (ABBAAB) and alternating (ABABAB) segments have attracted significant scientific interest, owing to their resulting microphase‐separated morphologies, different thermal and mechanical properties with a growing list of realized and potential applications . Currently, major sy nthesis methods to get MBCs relying on polycondensation can be divided into two categories, that is, click chemistry and coupling chemistry of α,ω‐dihydroxy to form urethane, ester, or amide bonds .…”