Direct C-H:C-H Arylation Polymerization of 3,4-Propylenedioxythiophene Derivatives

In this manuscript, we report, for the first time, a direct C-H:C-H arylation process for the polymerization of 3,4-propylenedioxythiophene derivatives. The requirement of aryl halides monomers can be completely excluded in this process, making the process atom economical and environmentally friendly. We could successfully homopolymerize Prodot-diethylhexyl using palladium acetate as catalyst. The optimized process required the stepwise ramping of the temperature from 70 °C to 140 °C. It was also observed that a direct heating of the polymerization mixture to 140 °C results in the decomposition of the catalyst leading to unsuccessful polymerization. At present, the exact mechanism of the whole process is not clear.

Imprinted polymers in analytical chemistry

Molecularly imprinted polymers were prepared and tested in different way. 1-methyl-2-piperidinoethylester of 4-decyloxyphenylcarbamic acid was used as template for imprints formation. Acrylamide, 4-vinylpyridine and methacrylic acid as monomers and methanol and acetonitrile as a porogene were used. Non-imprinted polymers (NIP) were prepared for each imprinted polymer by the same procedure. Polymers were employed as sorbents for solid-phase extraction (SPE). In this work the influence of polymerization mixture composition on polymer properties, such as capacity and selectivity, was investigated. The influence of alkoxy-chain length and position on benzene ring on the selectivity of polymers was also investigated.

The Use of Computational Methods for the Development of Molecularly Imprinted Polymers

Recent years have witnessed a dramatic increase in the use of theoretical and computational approaches in the study and development of molecular imprinting systems. These tools are being used to either improve understanding of the mechanisms underlying the function of molecular imprinting systems or for the design of new systems. Here, we present an overview of the literature describing the application of theoretical and computational techniques to the different stages of the molecular imprinting process (pre-polymerization mixture, polymerization process and ligand–molecularly imprinted polymer rebinding), along with an analysis of trends within and the current status of this aspect of the molecular imprinting field.

Synthesis and Properties of Bioresorbable Block Copolymers of l-Lactide, Glycolide, Butyl Succinate and Butyl Citrate

The paper presents the course of synthesis and properties of a series of block copolymers intended for biomedical applications, mainly as a material for forming scaffolds for tissue engineering. These materials were obtained in the polymerization of l-lactide and copolymerization of l-lactide with glycolide carried out using a number of macroinitiators previously obtained in the reaction of polytransesterification of succinic diester, citric triester and 1,4-butanediol. NMR, FTIR and DSC were used to characterize the materials obtained; wettability and surface free energy were assessed too. Moreover, biological tests, i.e., viability and metabolic activity of MG-63 osteoblast-like cells in contact with synthesized polymers were performed. Properties of obtained block copolymers were controlled by the composition of the polymerization mixture and by the composition of the macroinitiator. The copolymers contained active side hydroxyl groups derived from citrate units present in the polymer chain. During the polymerization of l-lactide in the presence of polyesters with butylene citrate units in the chain, obtained products of the reaction held a fraction of highly branched copolymers with ultrahigh molecular weight. The reason for this observed phenomenon was strong intermolecular transesterification directed to lactidyl side chains, formed as a result of chain growth on hydroxyl groups related to the quaternary carbons of the citrate units. Based on the physicochemical properties and results of biological tests it was found that the most promising materials for scaffolds formation were poly(l-lactide–co–glycolide)–block–poly(butylene succinate–co–butylene citrate)s, especially those copolymers containing more than 60 mol % of lactidyl units.

Potentiometric cholesterol biosensing application of graphene electrode with stabilized polymeric lipid membrane

Abstract A novel potentiometric cholesterol biosensor has been fabricated through the immobilization of the stabilized polymeric lipid membrane onto graphene electrode. The stabilized polymeric lipid membrane is composed of cholesterol oxidase enzyme and polymerization mixture; which holds paramount influence on the properties of the cholesterol biosensor. The presented biosensor reveals an appreciable reproducibility, good selectivity and high sensing capability with a linear slope curve of ∼64 mV per decade. The strong biocompatibility among stabilized polymeric lipid membranes and human biofluids provides the possibility to use for real blood samples and other biological applications. Graphical abstract

Recycling of Industrial Wastewater by its Immobilization in Geopolymer Cement

In this work, wastewater from Teva Pharmaceutical Industries Ltd., which comprises several organic and inorganic compounds, was solidified in a geopolymer matrix. The addition of wastewater to the polymerization mixture of fly ash based geopolymers yielded a high compressive strength of 50-75 MPa that is similar to that of wastewater-free geopolymer. The leaching of organic compounds from the matrix was examined and it was found to be negligible, about 0.2%wt, and comparable to the amount that leached from a geopolymer matrix made without wastewater. The results indicate that the immersion temperature and the time of immersion have negligible influences on carbon leaching.

Mechanisms for anionic butadiene polymerization with alkyl lithium species

Anionic butadiene polymerization by means of [Li-polybutadienyl]x species (x = 1–6, 8) without polar agents was investigated by means of density functional theory (DFT) under conditions relevant to industrial application, namely in a low-dielectric hydrocarbon solvent and at room temperature. The calculations indicate that the dimeric and tetrameric catalyst species together account for the bulk of Li-polybutadienyl species in the polymerization mixture under typical conditions. It is likely that each type of oligomer produces its own “fingerprint” signature polymer microstructure, as there is a systematic variation in the amounts of 1,2- and 1,4-insertions as well as in the preference of cis- and trans-butadiene. According to the calculations, higher aggregated Li species tend to produce more 1,2-insertions and prefer trans- over cis-butadiene insertion, while the dimer prefers trans-butadiene and 1,4-insertions. The dimer closely reproduces the experimentally observed polybutadiene microstructure (5%–10% 1,2-insertion, approximately equal ratios of cis and trans units with a slight predominance of trans). The monomeric catalyst species shows a clear preference for insertion of cis-butadiene over trans-butadiene. Thus, the monomer species is predicted to be present in the polymerization mixture in very small concentrations under normal conditions and the overall polymerization is predicted to be mainly carried out by the dimeric catalyst species.

Lithiated Thiaacetals as Initiators for Living Anionic Polymerization of Diene Elastomers: Polymerization and Compounding

Polybutadiene and poly(butadiene-co-styrene) elastomers were prepared in high conversions using 2-lithio-2- methyl-1,3-dithiane as the initiator. Polymers were readily prepared with a polydispersity index (PDI) of 1.05 to 1.26 and a Mn of up to 208 kg/mol. The replacement of the 2-methyl substituent with phenyl, trimethylsilyl or 4-dimethylamino phenyl also gave active initiators that incorporated at the head of the chain. However, initiation rates appeared to vary somewhat with the structure of the initiators. The polymerizations obtained are in all cases controlled and apparently living with the live chain ends capable of further reactions. The initiators could be generated prior to addition to the polymerization mixture or by an in-situ procedure. Model studies gave evidence that the dithiane chain end can be opened under cure conditions and react with unsaturation present in the polymer chain. Several of the product polymers were found to impart improved hysteresis to carbon and silica-filled rubbery vulcanizates possibly through an endlinking mechanism.