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.

A growing body of work shows that the phase behavior of supramolecular polymers assembled from telechelic building blocks featuring binding motifs at the two termini is quite similar to that of conventional block copolymers. However, it remains unclear how crystallization of the phase formed by the binding motifs, which occurs in many supramolecular polymers, affects the phase morphology of such materials. Here we report a systematic investigation of a series of supramolecular polymers based on poly(ethylene-cobutylene) (PEB) telechelics and the complementary H-bonding pair isophthalic acid−pyridine (IPA-Py). These polymers were designed to feature two blocks that assemble into an amorphous low-glass-transition phase formed by the PEB segments and crystalline domains consisting of the binding motifs. The nature of the latter was systematically varied via the choice of the pyridine employed. The influence of the binding motif on the phase morphology and thereby properties of these supramolecular polymers was investigated by means of thermal analysis, polarized optical microscopy, (dynamic) mechanical analyses, small-angle X-ray scattering, and transmission electron microscopy. In the melted state, all materials assembled into hexagonal phases. However, when cooled below the crystallization temperature of the IPA-Py domains, three different scenarios were observed: breakout crystallization resulting in complex morphologies, retention of the melt morphology, and the formation of a lamellar phase.

Due to their low melt viscosity, competitive adhesive properties, and the stimuli‐responsive nature of supramolecular interactions, various supramolecular polymers have recently been investigated as adhesives with on‐demand (de)bonding capability. The adhesive properties of a series of hydrogen‐bonded supramolecular polymer networks based on a telechelic poly(ethylene‐co‐butylene) (PEB) terminated with isophthalic acid (IPA) groups and a series of bifunctional pyridines (Py) are reported herein. These supramolecular polymers microphase segregate into an IPA‐Py rich hard phase and an amorphous low‐glass‐transition PEB phase, and their properties depend on the nature of the pyridine‐carrying monomer. Rheological measurements show that the polymers disassemble into low‐viscosity melts when heated above the melting or glass transition temperature of the hard phase. Lap joints bonded with the polymers display a shear strength of up to 1.3 MPa, and debonding is possible in less than 10 s upon heating or exposure to UV–light; to enable rapid light‐induced (de)bonding, a light–heat converter is introduced. Cyclic bonding/debonding experiments reveal that the shear strength remains unchanged over five cycles and demonstrate that the process is very robust.