Sylwia Golba

Studies on the radical polymerization of monomeric ionic liquids: nanostructure ordering as a key factor controlling the reaction and properties of nascent polymers

In this paper, the kinetics of the radical polymerization of two monomeric ionic liquids: 1-ethyl- and 1-butyl-3-vinylimidazolium bis(trifluoromethanesulfonyl)imide ([evim][NTf2] and [bvim][NTf2], respectively) as well as the molecular dynamics of the obtained polymers were investigated by means of Broadband Dielectric Spectroscopy (BDS), Fourier Transform Infra-Red (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC). We propose a novel method of dielectric data analysis, to extract information on the progress of polymerization in highly conductive materials. It was found that the progress of reaction can be easily monitored by measuring the time evolution of dc conductivity, which correlates very well with the monomer conversion estimated from calorimetric or FTIR investigations. Additionally, it is clearly shown that even a small modification in the chemical structure, i.e. the length of the alkyl substituent, of monomeric ionic liquids leads to a dramatic change in the properties of the produced polymers. The obtained results are discussed in light of recent studies indicating a completely different tendency to nanostructure ordering in the investigated monomeric ionic liquids.

Polycyclic aromatic hydrocarbons connected with Schiff base linkers: Experimental and theoretical photophysical characterization and electrochemical properties.

A series of polyaromatic hydrocarbons with anthracene, phenanthrene and pyrene units connected with Schiff base junctions were synthesized via condensation of p-phenylenediamine and hydrazine with selected aldehydes. The effect of both hydrocarbon structures and presence of N-N- or phenyl- linked diimines on properties of the prepared azines and azomethines was analyzed. The obtained compounds were soluble in common organic solvents and melted in the range of 226-317°C. Their photophysical and electrochemical properties were investigated by UV-vis, photoluminescence spectroscopies and cyclic voltammetry (CV), respectively. Moreover, a density functional theory (DFT) was applied for calculation of their electronic and geometric structures as well as absorption and emission spectra. Additionally, their electron acceptor activity was preliminary tested in photovoltaic experiment.

Ring-Opening Polymerization of Lactones Initiated with Metal Hydroxide-Activated Macrocyclic Ligands: Determination of Mechanism and Structure of Polymers

Anhydrous alkali metal hydroxide (KOH, NaOH, and LiOH)-activated macrocyclic ligand complexing metal cations, i.e., coronands 12C4, 15C5, 18C6, DCH24C8, and cryptand C222, were selected for initiation of β-butyrolactone (β-BL) and ε-caprolactone (ε-CL) polymerization. It was found that β-BL polymerizes in the presence of KOH/18C6, KOH/C222, and NaOH/C222 systems. The real initiators in this case are two salts, potassium 3-hydroxybutyrate and potassium trans-crotonate, which are responsible for the formation of two fractions of the obtained polymer. ε-CL underwent polymerization with KOH or NaOH activated by all ligands used or without the ligand but with LiOH/12C4. Using KOH-activated strong ligands, i.e., 15C5, 18C6, or C222, two polymer fractions were generated containing linear and, unexpectedly, also cyclic macromolecules. The mechanism of the studied processes is discussed.

High pressure water-initiated ring opening polymerization for the synthesis of well-defined α-hydroxy-ω-(carboxylic acid) polycaprolactones

The development of a green e-caprolactone (CL) polymerization method is the most important challenge in modern polymer chemistry. Herein, we propose a novel method to produce polyesters of a well-defined chemical structure, and narrow molecular weight distributions by using a combination of high pressure, temperature and water. We found two competitive phenomena: polymerization and crystallization occurring at high compression. Once the latter process is avoided, the control over the reaction is reached. By varying the thermodynamic conditions and concentration of water molecules, polymers of moderate molecular weights (Mn = 1.6–19.0 kg mol−1) and dispersities (Đ ≈ 1.07–1.50) could be produced. Additional NMR experiments supported by further MALDI TOF analysis enabled us to determine telechelic hydroxyl and carboxylic/acidic moieties as terminal groups of produced PCLs. Finally, the latter measurements also indicated that generally an increase in dispersity above 1.3 is strongly related to the competitive reactions leading to the production of cyclic polyesters. The presented results open up alternative routes to produce PCLs of enhanced biocompatibility and biodegradability using the greenest method reported to date.

Synthesis by Stille Cross-Coupling Procedure and Electrochemical Characterization of Branched Polymers Based on Substituted 1,3,5-Triarylbenzenes

A series of various substituted 1,3,5-triarylbenzenes, 2,4,6-triaryl-1-phenoles, 1,3,5-triaryl-1-methoxybenzenes and 2,4,6-triaryl-1,3,5-trimethoxybenzenes were synthesized by a Stille cross-coupling procedure. Their structures were confirmed by 1H NMR, 13C NMR, and elemental analysis. Containing thienyl, furyl and EDOT groups polymers obtained in the process of electropolymerization could be carefully considered as a building material in a wide range of organic-electronic devices. We compare properties of monomers and related polymers depending on aryls moieties and their influence of hydroxyl and methoxyl groups attached to the central benzene core.

Application of Dipotassium Glycoxides–Activated 18-Crown-6 for the Synthesis of Poly(propylene oxide) with Increased Molar Mass

Mono- and dipotassium salts of dipropylene glycol were applied for the polymerization of propylene oxide in mild conditions, i.e., tetrahydrofuran solution at ambient temperature. The structure of polymers was investigated by use of 13C NMR and MALDI-TOF techniques. The structure depends strongly on the kind of initiator and additives that are used such as coronand 18-crown-6 and dipropylene glycol. The lowest unsaturation, represented by allyloxy starting groups, has the polymer obtained by use of monopotassium salt without the ligand. The highest unsaturation degree is for the polymer synthesized in the presence of dipotassium salt–activated 18-crown-6. This polymer, obtained at high initial monomer concentration and low initial concentration of initiator, consists of two fractions, i.e., a low molar mass fraction (Mn = 9400) containing mainly macromolecules with alkoxide starting and end groups and a much higher molar mass fraction (Mn = 29500 g/mol) containing macromolecules with allyloxy starting groups and alkoxide or hydroxyl end groups. Addition of free glycol to this system decreases the molar mass of polymers. Similar results were obtained by use of dipotassium salts of other glycols. The mechanisms of the studied processes are discussed.

Mechanism of ε-caprolactone polymerization in the presence of alkali metal salts: investigation of initiation course and determination of polymers structure by MALDI-TOF mass spectrometry

Various alkali metal salts were applied as initiators for ε-caprolactone anionic ring-opening polymerization in tetrahydrofuran at room temperature. It was observed that potassium methoxide (MeOK), potassium isopropoxide (i-PrOK) and potassium tert-butoxide (t-BuOK) nonactivated or activated by 18-crown-6 (18C6) initiated polymerization mainly by deprotonation of the monomer. In the case of potassium hydride (KH), its basicity increased with the ability of the ligand for cation complexation. For example, KH without ligand or with weak ligands for K+ as 12C4 reacted exclusively by ring opening. However, in the presence of strong ligands, as 15C5, 18C6 or cryptand C222, basicity of H− increased with the ability of the ligand for cation complexation. In the last case, ~ 32% of the monomer was deprotonated. In these systems, gaseous H2 evolved during the initiation. Deprotonation of the monomer by some initiators resulted in macromolecules with reactive aldehyde group or lactone ring as starting groups. They took part in the reaction with potassium alkoxide active centers of growing chains leading to the formation of branched poly(ε-caprolactone)s. Sodium hydride (NaH) was inactive, but in the presence of 15-crown-5 or 18-crown-6 initiated polymerization exclusively by ring opening. MALDI-TOF mass spectrometry supported with 13C NMR and SEC was used for analysis of the polymers obtained. Mechanism of the studied processes was proposed and discussed.

The influence of initiator and macrocyclic ligand on unsaturation and molar mass of poly(propylene oxide)s prepared with various anionic system

Anionic polymerization of propylene oxide was carried out in the presence of two groups of potassium salts activated 18-crown-6 (18C6), e.g. alkoxide salts (CH3OK, i-PrOK, t-BuOK, CH3OCH2CH(CH3)OK, KCH2O) and other salts (CbK, Ph3CK, Ph2PK, Ph3HBK, KK, KH, and [(CH3)3Si]2NK) in THF at room temperature. Application of various initiating systems results in polyethers which are different in level and kind of unsaturation represented by allyloxy, cis- and trans-propenyloxy, as well as vinyloxy starting groups. In the presence of selected initiator, i.e. t-BuO−K+ unsaturation increases markedly by addition of 18C6 or C222. During the initiation step oxirane ring-opening and direct deprotonation of the monomer occur simultaneously involving in some cases also the ligand. All initiators opens oxirane ring in the β-position except i-PrOK, which opens it in the β- and α-position. The mechanisms of the reactions were discussed.

Electrochemical and spectrophotometric properties of polymers based on derivatives of di- and triphenylamines as promising materials for electronic applications

Novel phenylamine-substituted derivatives, possessing different photochromic groups, were investigated. The electrochemical activity of the monomers and polymers were studied by usage of the electrochemical and spectroelectrochemical measurements. Heterocyclic side rings influence on the oxidation potential of monomers, decreasing its value below oxidation potential in comparison to parent phenylamine units. The removal of electron is easier for diphenylamine derivatives than for the triphenylamine ones. Electroactivity of monomers allows to polymerize them into macromolecule chains. Triphenylamine-based polymers are more stable as a result of the enlarged conjugated systems. Furthermore, the energy gap value of the final polymer can be reduced by introduction of additional branch into the monomer structure.