Rapid Formation of a Lamellar Structure in an Amphiphilic Comb‐Shaped Polymer by Nanophase Separation Using Microwave–Humidity Annealing

Abstract

AbstractMicrowave irradiation is applied to rapidly prepare highly ordered lamellar structures of amphiphilic comb‐shaped polymers via nanophase separation. Amphiphilic comb‐shaped polymer of poly(N‐dodecyl acrylamide) (pDDA) is synthesized by free radical polymerization. Differential scanning calorimetry (DSC) and X‐ray diffraction results indicate that pDDA is amorphous at room temperature. Exposing pDDA powder to microwave irradiation in the presence of water (microwave–humidity annealing) converts the structure into lamellae. The water molecules absorb the microwaves, and their temperature rapidly increases above the glass‐transition temperature (Tg) of pDDA. Moreover, a fraction of the heated water is adsorbed at the amide moiety, which increases the nanosegregation with the alkyl side chains. As a result, pDDA forms a lamellar structure by nanophase separation between the main chain with water‐containing amide moieties and the alkyl side chains. The rapid increase in temperature results in a fast formation (a few tens of seconds) of the lamellae. Moreover, the microwave–humidity annealing of pDDA thin films on Si substrates results in a uniaxial lamellar structure. These results indicate that microwave–humidity annealing is a simple method to rapidly form a self‐assembled structure in homopolymers by nanophase separation.