Articolo in rivista, 2024, ENG, 10.3390/ma17030592

Morphology and Mechanics of Star Copolymer Ultrathin Films Probed by Atomic Force Microscopy in the Air and in Liquid

Albonetti, Cristiano and Izzo, Lorella and Vigliotta, Giovanni and Saponetti, Matilde Sublimi and Liscio, Fabiola and Bobba, Fabrizio

Consiglio Nazionale delle Ricerche, Istituto Per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), Via P. Gobetti 101, 40129 Bologna, Italy Consiglio Nazionale delle Ricerche, Istituto Superconduttori, Materiali Innovativi e Dispositivi (CNR-SPIN), Via Giovanni Paolo II, 132, 84084 Fisciano, SA, Italy Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi Dell'insubria, Via J.H. Dunant, 3, 21100 Varese, Italy; lorella.izzo@uninsubria.it Dipartimento di Chimica e Biologia "A. Zambelli", Università degli Studi di Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, SA, Italy; Dipartimento di Fisica "E.R. Caianiello", Università degli Studi di Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, SA, Italy; Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e i Microsistemi (CNR-IMM), Via P. Gobetti 101, 40129 Bologna, Italy;

Star copolymer films were produced by using spin-coating, drop-casting, and casting deposition techniques, thus obtaining ultrathin and thick films, respectively. The morphology is generally flat, but it becomes substrate-dependent for ultrathin films where the planarization effect of films is not efficient. The indentation hardness of films was investigated by Force Volume Maps in both the air and liquid. In the air, ultrathin films are in the substrate-dominated zone and, thus, the elastic modulus E is overestimated, while E reaches its bulk value for drop-casted ultrathin and thick films. In liquid (water), E follows an exponential decay for all films with a minimum soaked time t0 of 0.37 and 2.65 h for ultrathin and drop-casted ultrathin and thick films, respectively. After this time, E saturates to a value on average 92% smaller than that measured in the air due to film swelling. Such results support the role of film morphology in the antimicrobial activity envisaged in the literature, suggesting also an additional role of film hardness.

Materials (Basel) 17 (3), pp. 576–?

Keywords

films, star copolymers, morphology, AFM, force volume map

CNR authors

Albonetti Cristiano, Liscio Fabiola

CNR institutes

IMM – Istituto per la microelettronica e microsistemi, ISMN – Istituto per lo studio dei materiali nanostrutturati