This thesis focuses on the exploration of the advanced applications for zwitterionic-based polymers by considering the subdivision of these materials in two classes: stimuli responsive and non-stimuli responsive. For the former, the UCST of polysulfobetaine (pSB) and poly(sulfobetaine-cosulfabetaine) (pSB-rZB) synthesized via RAFT was analyzed in aqueous and physiological solutions allowing the analysis of the transition temperature dependence on the concentration, degree of polymerization and composition and the understanding of the “salting” effect influence on the transition temperature aiming to fill the gap of zwitterionic polymers with a UCST close to the body temperature in physiological conditions. Some samples of the polymers synthesized were selected and subjected to a sequential RAFT polymerization in order to attach a LCST block based on EG2MA and EG8MA and a biodegradable block composed by polycaprolactone-based macromonomers (HEMA-CLq or DMA-CLq) synthesized previously via ROP, creating thus a “schizophrenic” block copolymer. The effect of the different blocks composition on both UCST and LCST and on nanoparticles size was analyzed and two examples, one with a UCST block based on SB and the other on pSB-rZB were selected and subjected to the evaluation of the critical micellar concentration, degradation and, eventually, to pyrene loading and release tests. For the non-responsive case, the zwitterionic phosphorylcholine MPC was polymerized via RAFT and the resulting product was employed in a sequential RAFT polymerization with a negative monomer (SPMAK), a positive and fluorescent one (HEMA-RhB) and a crosslinker (EGDMA), delivering an overly neutral nanoparticle which was then subjected to diffusion tests to assess their functionality as nanotracers. Additionally, having confirmed the formers efficiency, equivalent polymerizations were performed with the incorporation of a neutral monomer (BMA) with the objective of producing nanotracers with bigger size.
Questa tesi si focalizza sullo studio delle applicazioni avanzate di polimeri a base di molecole zwitterioniche tenendo in considerazione la suddivisione di questi materiali in due classi: responsivi e non responsivi a stimoli. Per il primo, la UCST della polisulfobetaina (pSB) e poli(sulfobetaina-cosulfabetaina) (pSB-rZB), sintetizzate tramite RAFT, è stata analizzata in soluzioni acquose e fisiologiche, permettendo l’analisi della dipendenza della temperatura di transizione da concentrazione, grado di polimerizzazione e composizione, oltre che la comprensione dell’effetto “salting” su di essa, con lo scopo di colmare il vuoto di polimeri zwitterionici con una UCST vicina alla temperatura corporea in condizioni fisiologiche. Alcuni dei polimeri sintetizzati sono stati selezionati e sottoposti ad una RAFT sequenziale al fine di estenderli con un blocco LCST basato su EG2MA e EG8MA ed un blocco biodegradabile composto da macromonomeri a base di policaprolattone (HEMACLq o DMA-CLq) sintetizzati in precedenza tramite ROP, creando così un copolimero a blocchi “schizofrenico”. L’effetto della composizione dei blocchi su UCST e LCST e dimensioni delle nanoparticelle è stato analizzato, e due casi, uno con un blocco UCST a base di SB e l’altro a base di pSB-rZB, sono stati selezionati e studiati al fine di ricavarne la concentrazione micellare critica, il degrado nel tempo ed eventualmente il carico e rilascio di pirene. Per il caso non responsivo, lo zwitterionico fosforilcolina MPC è stato sintetizzato tramite RAFT e il prodotto risultante è stato impiegato in una successiva estensione di catena tramite polimerizzazione RAFT con un monomero negativo (SPMAK), uno positivo e fluorescente (HEMA-RhB), ed un cross-linkante (EGDMA), generando nanoparticelle globalmente neutre che sono state poi sottoposte a test di diffusione per valutarne la funzionalità come nanotraccianti. Inoltre, dopo aver provato la loro efficienza, sono state eseguite polimerizzazioni equivalenti con l’incorporazione di un monomero neutro (BMA) con l’obiettivo di produrre nanotraccianti con una dimensione più grande.
Zwitterionic colloids for advanced applications
RODRIGUES BASSAM, PAOLA
2017/2018
Abstract
This thesis focuses on the exploration of the advanced applications for zwitterionic-based polymers by considering the subdivision of these materials in two classes: stimuli responsive and non-stimuli responsive. For the former, the UCST of polysulfobetaine (pSB) and poly(sulfobetaine-cosulfabetaine) (pSB-rZB) synthesized via RAFT was analyzed in aqueous and physiological solutions allowing the analysis of the transition temperature dependence on the concentration, degree of polymerization and composition and the understanding of the “salting” effect influence on the transition temperature aiming to fill the gap of zwitterionic polymers with a UCST close to the body temperature in physiological conditions. Some samples of the polymers synthesized were selected and subjected to a sequential RAFT polymerization in order to attach a LCST block based on EG2MA and EG8MA and a biodegradable block composed by polycaprolactone-based macromonomers (HEMA-CLq or DMA-CLq) synthesized previously via ROP, creating thus a “schizophrenic” block copolymer. The effect of the different blocks composition on both UCST and LCST and on nanoparticles size was analyzed and two examples, one with a UCST block based on SB and the other on pSB-rZB were selected and subjected to the evaluation of the critical micellar concentration, degradation and, eventually, to pyrene loading and release tests. For the non-responsive case, the zwitterionic phosphorylcholine MPC was polymerized via RAFT and the resulting product was employed in a sequential RAFT polymerization with a negative monomer (SPMAK), a positive and fluorescent one (HEMA-RhB) and a crosslinker (EGDMA), delivering an overly neutral nanoparticle which was then subjected to diffusion tests to assess their functionality as nanotracers. Additionally, having confirmed the formers efficiency, equivalent polymerizations were performed with the incorporation of a neutral monomer (BMA) with the objective of producing nanotracers with bigger size.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/145132