Browsing by Subject "Ring-opening polymerization"

Now showing 1 - 4 of 4

Embargo
Eugenol-derived bio-benzoxazine resins: synthesis, characterization, and exceptional thermal stability
(John Wiley & Sons, Inc., 2024-06-20) Doğan, Yelda Ertaş; Uyar, Tamer
In this study, we succesfully synthesized bio-benzoxazine resins using eugenol, a bio-based phenolic compound, in combination with three distinct functional amines: ethanamine, aniline, and hexane-1,6-diamine. Characterization of the resulting bio-benzoxazine resins, namely E-ea (eugenol, ethanamine), E-a (eugenol, aniline), and E-dh (eugenol, hexane-1,6-diamine), was performed through H-1 NMR spectroscopy, FTIR spectroscopy, high-resolution mass spectrometry, and elemental analysis. Thermal properties were investigated using thermogravimetric analysis (TGA) for both the eugenol-derived bio-benzoxazines (E-ea, E-a, E-dh) and their corresponding polybenzoxazines (PE-ea, PE-a, PE-dh). Notably, all eugenol-based polybenzoxazines exhibited excellent thermal stability with very similar characteristics. Our findings suggest that the presence of allyl groups in eugenol promoted a more cross-linked network structure compared to other functional groups on amines. As a result, eugenol-derived bio-benzoxazines demonstrated superior thermal properties, illustrated by their impressive char yields: PE-ea; 45.6%, PE-a; 45.1%, and PE-dh; 44.1%.
Open Access
Poly(epsilon caprolactone)/clay nanocomposites via host-guest chemistry
(Elsevier Ltd, 2015) Arslan, M.; Tasdelen, M. A.; Uyar, Tamer; Yagci, Y.
Cyclodextrin-modified montmorillonite (MMT-CD) has been prepared from commercial montmorillonite clay (Closite 30B) containing two hydroxyl groups by reacting succinic anhydride through esterification. Poly(epsilon caprolactone) (PCL)/clay nanocomposites are prepared by host-guest chemistry between MMT-CD as host and PCL, hydrophobic polymer as guest. The structures of the intermediates and final nanocomposite are investigated in detail by FT-IR XRD, TEM, DSC and TGA measurements. The intercalated/exfoliated morphologies are determined by combined XRD and TEM analyses. Thermal stabilities of all nanocomposites are improved by the addition of MMT-CD compared to the neat polymer. The DSC data confirm that the crystallinity of PCL is slightly increased by increasing clay loading. © 2015 Elsevier Ltd. All rights reserved.
Open Access
Polymer/clay nanocomposites through multiple hydrogen-bonding interactions
(John Wiley and Sons Inc., 2015) Aydin, M.; Uyar, Tamer; Tasdelen, M. A.; Yagci Y.
An 2-ureido-4[1H]pyrimidinone (UPy) motif with self-association capability (through quadruple hydrogen bonds) was successfully anchored onto montmorillonite clay layers. Polymer/clay nanocomposites were prepared by specific hydrogen bonding interactions between surface functionalized silica nanoclays and UPy-bonded supramolecular poly(ethylene glycol) or poly(É-caprolactone). The mixed morphologies including intercalated layers with a non-uniform separation and exfoliated single layers isolated from any stack were determined by combined X-ray diffraction and transmission electron microscopic measurements. Thermal analyses showed that all nanocomposites had higher decomposition temperatures and thermal stabilities compared with neat polymer. The differential scanning calorimetric data implied that the crystallinity of polymers did not show essential changes upon introduction of organomodified UPy clays.
Open Access
Synthesis and characterization of ABA-Type triblock copolymers using novel bifunctional PS, PMMA, and PCL macroinitiators bearing p-xylene-bis(2-mercaptoethyloxy) core
(MDPI AG, 2023-09-18) Mısır, M.; Savaşkan Yılmaz, Sevil; Bilgin, A.
Syntheses of novel bifunctional poly(methyl methacrylate) (PMMA)-, poly(styrene) (PS)-, and (poly ε-caprolactone) (PCL)-based atom transfer radical polymerization (ATRP) macroinitiators derived from p-xylene-bis(1-hydroxy-3-thia-propanoloxy) core were carried out to obtain ABA-type block copolymers. Firstly, a novel bifunctional ATRP initiator, 1,4-phenylenebis(methylene-thioethane-2,1-diyl)bis(2-bromo-2-methylpropanoat) (PXTBR), synthesized the reaction of p-xylene-bis(1-hydroxy-3-thia-propane) (PXTOH) with α-bromoisobutryl bromide. The PMMA and PS macroinitiators were prepared by ATRP of methyl methacrylate (MMA) and styrene (S) as monomers using (PXTBR) as the initiator and copper(I) bromide/N,N,N′,N″,N″-pentamethyldiethylenetriamine (CuBr/PMDETA) as a catalyst system. Secondly, di(α-bromoester) end-functionalized PCL–based ATRP macronitiator (PXTPCLBr) was prepared by esterification of hydroxyl end groups of PCL-diol (PXTPCLOH) synthesized by Sn(Oct)2–catalyzed ring opening polymerization (ROP) of ε-CL in bulk using (PXTOH) as initiator. Finally, ABA-type block copolymers, PXT(PS-b-PMMA-b-PS), PXT(PMMA-b-PS-b-PMMA), PXT(PS-b-PCL-b-PS), and PXT(PMMA-b-PCL-b-PMMA), were synthesized by ATRP of MMA and S as monomers using PMMA-, PS-, and PCL-based macroinitiators in the presence of CuBr/PMDETA as the catalyst system in toluene or N,N-dimethylformamide (DMF) at different temperatures. In addition, the extraction abilities of PCL and PS were investigated under liquid–liquid phase conditions using heavy metal picrates (Ag+, Cd2+, Cu2+, Hg2+, Pb2+, and Zn2+) as substrates and measuring with UV-Vis the amounts of picrate in the 1,2–dichloroethane phase before and after treatment with the polymers. The extraction affinity of PXTPCL and PXTPS for Hg2+ was found to be highest in the liquid–liquid phase extraction experiments. Characterizations of the molecular structures for synthesized novel initiators, macroinitiators, and the block copolymers were made by spectroscopic (FT–IR, ESI–MS, 1H NMR, 13C NMR), DSC, TGA, chromatographic (GPC), and morphologic SEM.