Self-assembling behaviors of amphiphilic polymers: From unimer micelles in solutions to nanostructured surfaces in thin films

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Doctoral school in Chemistry and material sciences (XXXIII cycle 2018/2020)

Activities report

CANDIDATE: Elena Masotti;

SUPERVISORS: Prof. Giancarlo Galli, Dr.ssa Elisa Martinelli; COORDINATOR: Prof. Gennaro Pescitelli.

SCIENTIFIC AREA FRAMEWORK: CHIM/05 CHIMICA INDUSTRIALE

PhD THESIS TITLE: Self-assembling behaviors of amphiphilic polymers: From unimer micelles in solutions to

nanostructured surfaces in thin films

ABSTRACT:

The PhD work was aimed to investigate novel types of amphiphilic synthetic polymers, where hydrophobic intramolecular interactions drive self-assembling into nanostructures in water solution and at the surface of thin solid films. In particular, attention was focused on the understanding of the morphology of self-assembled structures in relation to the nature of the hydrophobic component in the different polymers and to the variation of the temperature and concentration. To obtain a good control on the (co)polymerization the ARGET-ATRP and RAFT methods were used. In this way, we succeeded in preparing (co)polymers featuring diverse chemical architectures as well as tailored and varied philic/phobic balances.

Three major classes of amphiphilic polymers were newly developed: i) Random copolymers of polyethyleneglycol methyl ether methacrylate (PEGMA) as an hydrophilic and thermoresposive component with perfluorohexylethyl acrylate (FA) or polydimethylsiloxane methacrylate (SiMA) as an hydrophobic component. Triethyleneglycol methyl ether methacrylate (TRIGMA) was also used as an alternate comonomer in order to depress hydrophilicity of the respective copolymers. ii) Homopolymers of hydrophobic tetrafluorostyrene monomers modified by inserting an oligoethylene segment with varied chain lengths. iii) Random copolymers based on hydrophilic zwitterionic phosphorylcholine methacrylate (MPC) or sulfobetaine methacrylate (MSA) with 3-(trimethoxysilyl)propyl methacrylate (PTMSi) and copolymers of an hydrophobic FA with PTMSi.

Detailed characterization of the (co)polymers by dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS) measurements confirmed the formation of self-folded, intrachain nanostructures, or unimer micelles, for amphiphilic fluorinated copolymers of type i) in water solutions at room temperature. All polymers exhibited a reversible LCST-like behavior in water solutions, as identified by a transition temperature Tc that depended on the nature and composition of the amphiphilic polymers. The self-folded nanostructures clustered together into interchain aggregates above Tc, that quite

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reversibly collapsed back to unimer micelles on cooling below Tc. By contrast, all copolymers showed a conventional random coil conformation in organic solvents. A similar thermoresponsive behavior of intrachain nanostructures was observed with homopolymers of type ii), whose Tc was influenced by the overall hydrophobic/hydrophilic balance, as identified by the length of poliethylene glycol side chains. Fluorescent molecular probes were used to observe the self-assembly behavior of fluorinated amphiphilic copolymers. In particular, the single chain folding process was investigated through both a covalent functionalization and physical dispersion of two different hydrophobic dyes (2-cyano-2-[4-[vinyl(1-1’-biphenyl)-4’-yl]vinyljulolidine (JBCF) and coumarin 153 respectively) by fluorescence emission spectroscopy. The results of these preliminary analyses suggested the possibility of using the designed fluorinated copolymers as systems for controlled loading of hydrophobic molecules and possible release in response to a change in the embedding environments.

Random copolymers of type iii) were developed in which the zwitterion monomers MPC or MSA and hydrophobic FA were combined with functional PTMSi for tethering on glass substrates, thereby creating functional supported films incorporating nanostructuring additives. Experiments by static contact angle measurements, X-ray photoelectron spectroscopy, surface zeta potential and fluorescence spectroscopy analyses were applied to prove the effective anchoring of the polymeric films on the glass substrate before and after immersion in water. Then, antifouling potential of the films was demonstrated in biological assays against the adhesion of the yeast pathogen Candida albicans, chosen as a model fungal microorganism. The fluorinated copolymers were much more able to reduce fungal adhesion than did the zwitterionic MPC and MSA polymers.

RESEARCH EXPERIENCE IN OTHER INSTITUTIONS:

- Institution: Graz Thecnology University;

- Tutor: Prof. Uhling;

- Duration: From 1/10/2019 to 31/01/2020;

- Activities and results: The project developed at the Graz University of Technology) was focused on

the study of the morphology and conformation of the unimolecular nanoobjects and their intermolecular aggregates formed by amphiphilic copolymers with different hydrophilic/hydrophobic balance in water solution and in organic solution via small-angle X-ray scattering (SAXS) methods. Moreover, the transitions between the different modes of aggregation in solution (unimolecular, multichain and interactions with hydrophobic molecules) as a function of temperature were investigated by SAXS.

LIST OF ATTENDED PhD PROGRAMMES:

 Academic English:

- Academic year: 2017-2018;

- Location: University of Pisa;

- Professor: Steven Smith;

- Duration: 40 h;

 Paramagnetic NMR:

- Professor: Lorenzo Di Bari;

- Duration: 3 h;

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- Professor: Sokolova’s;

- Duration: 6 h;

 NMR allo stato solido:

- Professor: Marco Geppi;

- Duration: 28 h;

 Corso di Formazione “Gas compressi e criogenici liquefatti”: - Academic year: 2018-2019;

- Professor: Marco Martinelli;

- Duration: 4 h;

 Corso di Formazione “Differential scanning a calorimetry (DSC)”: - Academic year: 2018-2019;

- Duration: 7 h.

LIST OF ATTENDED RESEARCH SEMINARS:

 “Dalla ricerca all’impresa- Seminari di animazione imprenditoriale”: - Date:29/11/2017;

- Duration: 4 h;

 “Microfludics for flexible and intensified operations”: - Date: 12/01/2018;

- Location: University of Pisa

- Duration: 4 h;

 “Matching di trasferimento tecnologico e placement””: - Date: 20/04/2018;

- Duration: 4 h;

 “Many-Body expanded full configuration interaction”: - Date: 28/08/2018;

- Professor: Jurgen Gauss;

- Duration: 2 h;

 “From chemistry to radiocarbon dating: improving the chronologies of the past using supercritical fluids and chromatography”:

- Date: 25/09/2018;

- Professor: Thibaut Deviese;

- Duration: 4 h;

 “Synthetic approaches to the development of new antibody-drug delivery conjugates charged with unconventional payloads”:

- Academic year: 2018;

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- Duration: 2 h;

 “Vibrational spectra of chiral smectic liquid crystals differing in the molecular and helical structure”: - Date: 04/12/2018;

- Professor: Anna Drzewicz (Military University of thecnology);

- Duration: 2 h;

 “Chirality luminescence and single-molecule magnets in lanthanide based compounds for circularity polarized luminescence”:

- Date: Dic. 2018;

- Professor: Fabrice Pointillart (University of the Remes France);

- Duration: 2 h;

 “Self-assembly as nanofabrication tool”:

- Date: 04/02/2019 - 05/02/2019 - 11/02/2019 – 12/02/2019;

- Professor: Enrico Dalcanale (University of Parma);

- Duration: 8 h;

 “Nanochemistry: shaping the material the atomic and molecular level”: - Date: 20/02/2019;

- Professor: Angela Agostiano (University - CNR- IPCF of Bari);

- Duration: 2 h;

 “Design of magnetic nano-architectures for application in biomedice and energy”: - Date: 07/05/2019;

- Professor: George Thomas;

- Duration: 2 h;

 “Green synthesis of iron nanoparticles by plant extracts and used for the removal of contaminants”: - Date: 25/07/2019;

- Professor: Zuliang Chen (School of environmental science and engineering);

- Duration: 2 h;

 “Anti-van’t hoff-le bel configuration at the heavier group 14 elements”: - Date: Nov. 2019;

- Professor: Vladimir Ya Lee (University of Tsukuba);

- Location: University of Graz

- Duration: 2 h;

 “From: small tailor-made molecules to: new materials”: - Date: Nov. 2019;

- Professor: Heimrich Lang;

- Duration: 1 h;

 “Germane chemistry: from molecules to materials”: - Date: Nov. 2019;

- Professor: Kim M. Baines (University of western Ontario);

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 “From multidimensional nanomaterials-based biosesing to nanotheragnostics”: - Date: 05/02/2020;

- Professor: Arben Merkigi (Barcelona);

- Duration: 2 h;

 “Membrane and membrane process”:

- Date: 06/02/2020 - 07/02/2020 - 10/02/2020 - 11/02/2020;

- Professor: Antonio Lomite;

- Location : University of Pisa

- Duration: 8 h;

 “Functionalized cellulose, nanocrystals: new application of an old & new biopolymer”: - Date: 18/02/2020;

- Professor: Alessandra Opermolla

- Duration: 1 h;

 “Synthesis, characterization and manipulation of transition metal oxide nanostrucutures”: - Date: 19/02/2020;

- Professor: Veronica Salguermò;

- Duration: 1 h;

 “Magnetic and (Chir-) optical proprieties of lanthanide complexes through the prism of an inhibition calculations”:

- Date: 20/02/2020;

- Professor: Le Guennic (University of Rennes );

- Duration: 1 h;

 “Introduction to classic molecular dynamic simulation”: - Date: 02/03/2020;

- Duration: 2 h;

 “Metal ions, metal-based anticancer drugs and their interactions with specific biomolecules. A story that starts from far way”:

- Date: 20/02/2020;

- Professor: Alessandro Pratesi;

- Duration: 2 h;

 “The chemistry of electronic materials: small and perfect”: - Date: 28/04/2020;

- Professor: Christophen K. Ober;

- Location : Microsoft Teams

- Duration: 1 h.

LIST OF ATTENDED CONFERENCES:

 EUPOC 2018- Biomimetic polymers by rational design, imprinting and conjugation- Como (Italy) 20-24 May 2018 (POSTER: “THE TEMPERATURE-RESPONSIVE NANOASSEMBLIES OF AMPHIPHILIC RANDOM COPOLYMERS CARRYING POLY(SILOXANE) AND POLY(OXYETHYLENE) PENDANT CHAINS” Elena Masotti, Elisa Martinelli, Luisa Annunziata, Elisa Guazzelli, Andrea Pucci, Tarita Biver, Giancarlo Galli);

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