Porozni polimeri, pripravljeni s polimerizacijo z odpiranjem obroča v emulziji

doktorska disertacija

Petra Utroša (Author), David Pahovnik (Mentor), Sebastijan Kovačič (Co-mentor)

Abstract

V okviru doktorske disertacije smo s polimerizacijo z odpiranjem obroča (ROP) v zvezni fazi emulzij z visokim deležem interne faze (HIPE) polimerizirali heterociklične monomere. Prednost ROP neposredno v HIPE-u je v tem, da lahko pripravimo popolnoma razgradljiva poliHIPE-ogrodja specifične morfologije na osnovi poliestrov in sintetičnih polipeptidov. Za uspešno izvedbo ROP v HIPE-u smo pripravili brezvodne emulzije in uporabili organske katalizatorje, ki omogočajo izvedbo ROP pri relativno nizkih temperaturah in primerni hitrosti polimerizacije. Hitrost ROP v HIPE-u se je izkazala kot izredno pomemben parameter, saj mora zvezna faza emulzije želirati v času stabilne emulzije, obenem pa mora biti viskoznost emulzije primerna za zadovoljivo mešanje in prenos v primerne modele. %V prvem delu doktorskega dela predstavljamo poliHIPE na osnovi semikristaliničnega poliestra, poli(%-kaprolaktona) (PCL). S stopnjo zamreženosti smo vplivali na termomehanske lastnosti PCL poliHIPE-materiala, ki izkazuje oblikovni spomin. Oblikovni spomin smo raziskali s termomehanskimi cikličnimi testi in pokazali, da ga odlikujeta odlična fiksacija začasne oblike pri nizki temperaturi in odlična povrnitev v prvotno obliko med segrevanjem nad temperaturo tališča. Manj zamrežen poliHIPE ima višji temperaturi taljenja in kristalizacije in ga lahko fiksiramo že pri sobni temperaturi. %Metodo ROP v HIPE-u smo razširili na različne vrste N-karboksianhidridov (NCA) %-aminokislin ter kot prvi pripravili poliHIPE-materiale iz sintetičnih polipeptidov. Hitrost polimerizacije se je izkazala kot izredno pomemben parameter za uspešno pripravo poliHIPE sintetičnih polipeptidov, saj mora omogočati nadzorovano izhajanje plinastega ogljikovega dioksida, ki se sprošča med ROP NCA. Sintezni postopek, ki smo ga razvili, omogoča sintezo poliHIPE-ogrodij na osnovi polipeptidov različne kemijske sestave, pri čemer je zaradi razlik v reaktivnosti NCA-monomerov za vsak sistem reaktantov potrebno prilagoditi eksperimentalne pogoje sinteze, kot so koncentracija monomerov, količina katalizatorja, količina surfaktanta, vrsta zamreževalca in topila. Vzpostavili smo relacije med sintezo, strukturo in lastnostmi sintetiziranih poliHIPE-ov ter postavili temelje za načrtovanje in pripravo različno funkcionaliziranih polipeptidnih poliHIPE-materialov. Pokazali smo, da lahko z deležem interne faze in količino surfaktanta prilagajamo morfologijo poliHIPE, ki igra pomembno vlogo pri uporabi materiala v namen gojenja celic. Na izbranem polipeptidnem poliHIPE-u smo potrdili, da material ni toksičen za celice ter da omogoča njihovo rast in proliferacijo. V nadaljevanju smo pokazali, da je razvita metoda primerna za pripravo poliHIPE-polimerov na osnovi različnih polipeptidov, kot tudi kopolipeptidov. Pokazali smo tudi, da lahko z odščito zaščitenih stranskih skupin polipeptidov pripravimo poliHIPE-hidrogele, ki omogočajo nadaljnje popolimerizacijske modifikacije. Opisan pristop k pripravi polipeptidnih poliHIPE-ov obeta načrtovanje in pripravo makroporoznih ogrodij na osnovi sintetičnih polipeptidov različne kemijske sestave, katerih funkcionalnost lahko enostavno prilagajamo z izborom NCA-monomerov.

Keywords

polimerizacija z odpiranjem obroča (ROP);emulzije z visokim deležem interne faze (HIPE);poli(%-kaprolakton) (PCL);oblikovni spomin;sintetični polipeptidi;tkivno inženirstvo;doktorske disertacije;

Data

Language:	Slovenian
Year of publishing:	2021
Typology:	2.08 - Doctoral Dissertation
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[P. Utroša]
UDC:	66.095.26:57.086.83(043.3)
COBISS:	77206019
Views:	393
Downloads:	55
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Porous polymers prepared by ring-opening polymerization in emulsions
Secondary abstract:	In this doctoral thesis, ring-opening polymerization (ROP) of heterocyclic monomers in a continuous phase of high internal phase emulsions (HIPEs) was performed. ROP directly in HIPE enables the preparation of fully degradable polyester and synthetic polypeptide polyHIPEs with specific porous morphology. For the successful implementation of ROP in HIPE, anhydrous HIPEs were prepared and organic catalysts were used to enable ROP at relatively low temperatures and suitable polymerization rate. It has been shown that the rate of ROP in HIPEs is an extremely important parameter, as the continuous phase of the emulsion must gel within the time-frame of emulsion stability, while at the same time the HIPE viscosity must be suitable for adequate stirring and transfer of emulsions into the molds. %In the first part of the work, polyHIPEs based on a semi-crystalline polyester, poly(%-caprolactone) (PCL), are presented. The thermomechanical properties of the prepared PCL polyHIPEs were investigated and found to be strongly dependent on the degree of PCL crosslinking. PCL polyHIPEs exhibit shape memory behavior with excellent fixation of the temporary shape at low temperatures and excellent recovery of the original shape when heated above the melting temperature, as demonstrated by cyclic thermomechanical tests. Less crosslinked polyHIPE shows higher melting and crystallization temperatures and as a result, its temporary shape can be fixed even at room temperature. %The synthetic method was further extended to the polymerization of various types of %-amino acid N-carboxyanhydrides (NCAs) to prepare synthetic polypeptide polyHIPEs not previously reported. The polymerization rate has been shown to be an extremely important parameter for the successful preparation of polypeptide polyHIPEs, as it determines the rate of carbon dioxide release from HIPE during the ROP of NCA monomers. The synthetic process we developed allows the synthesis of polypeptide polyHIPE scaffolds with different chemical compositions. However, due to the different reactivity of NCA monomers, it is necessary to adjust the experimental conditions such as monomer concentration, catalyst amount, surfactant amount, type of crosslinker and type of solvent. Moreover, we have established relationships between the synthesis, structure and properties of the synthesized polyHIPE scaffolds and laid the foundation for the design and preparation of differently functionalized polypeptide polyHIPE scaffolds. We have shown that the morphology of the polyHIPEs, which plays an important role in the use of the material for cell culture, can be adjusted by the proportion of the internal phase in HIPE and the amount of surfactant. In the case of selected polypeptide polyHIPE, we have confirmed that the material is nontoxic to cells and that it allows good viability, migration and proliferation of cells throughout the polypeptide polyHIPE scaffold. Furthermore, the disclosed synthetic procedure is applicable for the preparation of polyHIPEs based on various polypeptides as well as copolypeptides. In addition, we have shown that we can prepare polyHIPE hydrogels by deprotecting the protected side groups of polypeptides. The unprotected functional groups allow further postpolymerization modifications of the polyHIPEs. The described approach to the preparation of polypeptide polyHIPEs promises the design and preparation of macroporous polypeptide scaffolds with different chemical compositions, whose functionality can be tuned simply by selecting the types of NCA monomers.
Secondary keywords:	ring-opening polymerization (ROP);high internal phase emulsion (HIPE);poly(%-caprolactone) (PCL);shape memory;synthetic polypeptides;tissue engineering;
Type (COBISS):	Doctoral dissertation
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	XVI, 113 str.
ID:	12794422