Toughening of Glassy Supramolecular Polymer Networks

Abstract

A modular approach for the design of two-component supramolecular polymer (SMP) networks is reported. A series of materials was prepared by blending two (macro)­monomers based on trifunctional poly­(propylene oxide) (PPO) cores that were end-functionalized with hydrogen-bonding 2-ureido-4­[1H]­pyrimidinone (UPy) groups. One monomer was based on a PPO core with a number-average molecular weight (M n) of 440 g mol–1. The SMP formed by this building block is a glassy, brittle material with a glass transition temperature (T g) of about 86 °C. The second monomer featured a PPO core with an M n of 3000 g mol–1. The SMP formed by this building block adopts a microphase-segregated morphology that features a rubbery phase with a T g of −58 °C and crystalline domains formed by the UPy assemblies, which act as physical cross-links and melt around 90–130 °C. Combining the two components allows access to microphase-segregated blends comprised of a rubbery phase constituted by the high-M n cores, a glassy phase formed by the low-M n component, and a crystalline phase formed by UPy groups. This allowed tailoring of the mechanical properties and afforded materials with storage moduli of 37–609 MPa, tensile strengths of 2.0–5.4 MPa, and melt viscosities of as low as 11 Pa s at 140 °C. The materials can be used as reversible adhesives.

Stepwise Crystallization and Induced Microphase Separation in Nucleobase-Monofunctionalized Supramolecular Poly(ε-caprolactone)

“…15,16 It is well known that block copolymers can self-assemble into diversified ordered structures depending on the degree of polymerization and the compatibility of the different blocks. 17−19 However, it is rather difficult to achieve a long-range ordered structure through the microphase separation of MHB-functionalized supramolecular polymers, which generally aggregate in the disordered structure on a long-range scale, 14,20 which is partially attributed to the complicated effects of noncovalent interactions and the compatibility of the polymer and the end groups.…”

CO2-based Biodegradable Supramolecular Polymers with Well-tunable Adhesive Properties

“…This is due to the low light-heat converter content used, which translates into much lower absorbance of the incident light. [35] Furthermore, re-attachment experiment was carried out, wherein the original adhesive strength of a steel lap joint sample could be well-recovered when rebounded at 120 °C for 180 s after it failed in the previous adhesive experiment (Fig. 4d).…”

3D and 4D printable dual cross-linked polymers with high strength and humidity-triggered reversible actuation

“…While the Young's modulus was measured to be B30 MPa, similar observation has also been reported for other glassy supramolecular polymers with Young's modulus of 35 MPa. 66 The chain mobility could be promoted in wet conditions as demonstrated by the frequency sweep showing a crossover where G 0 = G 00 at frequency of 2.8 Hz (Fig. S13B, ESI †).…”