Order Of Monomer Addition Research Articles

Impact of optimised quasi-block structures on the properties of polymer electrolytes.

A set of ionic quasi-block copolymers were investigated to determine the effects of their composition and structure on their performance in their application as solid-state battery electrolytes. Diffusion and electrochemical tests have shown that these new quasi-block electrolytes have comparable performance to traditional block copolymers reaching ionic conductivities of 3.8 × 10-4 S cm-1 and lithium-ion diffusion of 4.6 × 10-12 m2 s-1 at 80 °C. It was illustrated that the mechanical properties of each quasi-block electrolyte are highly dependent on the order of monomer addition in polymer synthesis while the phase morphology hints at each of the quasi-blocks' unique compositional make up.

Synthesis, characterization, and properties of thermoplastic polyimides derived from 4,4’-(hexafluoroisopropylidene)diphthalic anhydride in diethylene glycol dimethyl ether

By regulating the order of monomer addition, four kinds of copolymer polyimides (PIs) were prepared using diethylene glycol dimethyl ether (DEGDE) and N, N-dimethylacetamide (DMAc) as the solvents. The molecular weights of polyamide acids (PAAs) ranged from 3.8 × 105 to 9.2 × 105. All of the films displayed high glass transition temperatures ( Tgs) ranging from 313°C to 346°C. The polymer films show excellent thermal stabilities with 5% weight loss at temperatures of 505–524°C and char yields at 800°C were as high as 55% under nitrogen. The peel strengths of flexible copper (Cu) clads were in the range from 0.337 N cm−1 to 0.598 N cm−1. Compared to the molecular weight and peel strength of fresh PAA, those of PAAs prepared using DMAc significantly decreased after storage for 3 months at 0°C. However, when DEGDE was used as the solvent, the molecular weights of the PAAs and the thermal properties of the PIs were maintained after long storage time.

Synthesis of PEGylated poly(amino acid) pentablock copolymers and their self‐assembly

AbstractPentablock copolymers with an ABCBA architecture were synthesized by ring‐opening polymerization of N‐carboxyanhydrides of l‐leucine and γ‐benzyl l‐glutamate using an α, ω‐diamino poly(ethylene glycol) (PEG) as macroinitiator. Three different PEGs with molecular weights of 2000, 4600 and 10 000 Da were used and the poly(amino acid) (PAA) block lengths were set to a combined 10 and 40, respectively, repeat units for p(l‐Leu) and 40 repeat units for p(l‐Glu). The molecular architecture of the resulting pentablock copolymers was determined by the order of monomer addition. The living character of the N‐carboxyanhydride ring‐opening polymerization enables the formation of multiblock copolymers. The degree of polymerization for the PAA blocks matched the monomer/initiator ratio. A structural switch element, which controls the hydrophilicity of the pentablock copolymers, was incorporated in the form of the p(l‐Glu) blocks. The pentablock copolymers became water soluble after hydrolyzing the benzyl ester protective groups. The pentablock copolymers self‐assembled into polymeric aggregates ranging in size between 160 and 340 nm. Hydrogels formed readily if the central PEG block had a molecular weight of at least 4600 Da and the terminal A‐blocks consisted of p(l‐Leu). SEM images confirmed the size ranges of the polymeric aggregates and showed non‐distinct spherical aggregates. © 2016 Society of Chemical Industry

ChemInform Abstract: A Guide to the Synthesis of Block Copolymers Using Reversible‐Addition Fragmentation Chain Transfer (RAFT) Polymerization

AbstractReview: 50 refs.

A guide to the synthesis of block copolymers using reversible-addition fragmentation chain transfer (RAFT) polymerization

The discovery of reversible-deactivation radical polymerization (RDRP) has provided an avenue for the synthesis of a vast array of polymers with a rich variety of functionality and architecture. The preparation of block copolymers has received significant focus in this burgeoning research field, due to their diverse properties and potential in a wide range of research environments. This tutorial review will address the important concepts behind the design and synthesis of block copolymers using reversible addition-fragmentation chain transfer (RAFT) polymerization. RAFT polymerization is arguably the most versatile of the RDRP methods due to its compatibility with a wide range of functional monomers and reaction media along with its relative ease of use. With an ever increasing array of researchers that possess a variety of backgrounds now turning to RDRP, and RAFT in particular, to prepare their required polymeric materials, it is pertinent to discuss the important points which enable the preparation of high purity functional block copolymers with targeted molar mass and narrow molar mass distribution using RAFT polymerization. The key principles of appropriate RAFT agent selection, the order of monomer addition in block synthesis and potential issues with maintaining high end-group fidelity are addressed. Additionally, techniques which allow block copolymers to be accessed using a combination of RAFT polymerization and complementary techniques are touched upon.

Synthesis and Characterization of Branched Water-Soluble Homopolymers and Diblock Copolymers Using Group Transfer Polymerization

Group transfer polymerization [GTP] was used to synthesize branched statistical copolymers by copolymerizing either 2-(dimethylamino)ethyl methacrylate) [DMA] or 2-(diethylamino)ethyl methacrylate) [DEA] with ethylene glycol dimethacrylate (EGDMA) in THF at 20 °C. Since GTP has reasonable “living” character, it allows good control over both the primary chain length and the molecular weight distribution compared to previous branched vinyl polymers synthesized using conventional radical polymerization. Using GTP allows a remarkably high proportion of EGDMA brancher to be copolymerized without causing macrogelation. This unexpected result is attributed to a significant amount of intramolecular cyclization occurring (in addition to intermolecular branching) in these syntheses. Branched diblock copolymers based on DMA and DEA were prepared by sequential monomer addition, with EGDMA being used to achieve branching in either the DMA block or the DEA block or in both blocks. The order of monomer addition was vari...

Living Cationic Polymerization of α-Methylstyrene. 2. Synthesis of Block and Random Copolymers with 2-Chloroethyl Vinyl Ether and End-Functionauzed Polymers†

Abstract Both AB and BA block copolymers of α-methylstyrene (αMeSt) and 2-chloroethyl vinyl ether (CEVE) were synthesized by the sequential living cationic polymerization initiated with the HCl-CEVE adduct (1a)/SnBr4 system in CH2Cl2 at -78°C. αMeSt-CEVE (AB) block copolymers with narrow molecular weight distributions ([Mbar]w/[Mbar]n ∼ 1.15) were obtained when αMeSt was polymerized first, followed by addition of CEVE to the resulting αMeSt living polymer solution. The reverse order of monomer addition, from CEVE to αMeSt, also led to a BA-type block copolymer. In the polymerization of a mixture of the two monomers, almost random copolymers were obtained. Living polymerizations of αMeSt were also induced with functional initiating systems, HCl-functionalized vinyl ether adducts (1b-1d)/SnBr4, to give end-function-alized poly(αMeSt)s with a methacrylate, an acetate, or a phthalimide terminal.

Synthesis of block copolymers from 1‐chloro‐1‐octyne and other acetylenes through their sequential living polymerization by MoOCl4n‐Bu4SnEtOH

AbstractBlock copolymerizations of 1‐chloro‐1‐octyne (1‐ClO) with several substituted acetylenes were examined by means of living polymerization. o‐(Trifluoromethyl)phenylacetylene (o‐CF3PA), o‐(trimethylsilyl)phenylacetylene (o‐Me3SiPA), 1‐chloro‐2‐phenylacetylene (1‐ClPA), p‐butyl‐o,o,m,m‐tetrafluorophenylacetylene (p‐BuF4PA), and tert‐butylacetylene (t‐BuA) were used as comonomers, and the MoOCl4‐n‐Bu4Sn‐EtOH (mole ratio 1:1:1) catalyst, which is known to effect living polymerization of substituted acetylenes, was employed. When o‐CF3PA and 1‐CIPA were the comonomers in combination with 1‐CIO, block copolymers were exclusively obtained in both orders of monomer addition. In the cases of o‐Me3SiPA and p‐BuF4PA as comonomers, the copolymerizations initiated from 1‐CIO produced block copolymers selectively, whereas the homopolymers of o‐Me3SiPA and p‐BuF4PA also formed if the order of monomer addition was reversed. The pair of 1‐CIO and t‐BuA did not selectively yield block copolymers irrespective of the order of monomer addition. Thus, block copolymerization occurred between 1‐CIO and monomers that show high “livingness” and close reactivities.

Surface analysis of polymers and catalysts

The use of solid-state mass spectrometry for studying polymers is evaluated. Structural differences between polymers can be obtained by laser mass spectrometry by observing fingerprint-like spectra in the range m/z<250. Secondary-ion mass spectra (SIMS) revealed fragments that show the spacing of the repeat unit of the polymer up to m/ z 3,500. Oligomer distributions of low molecular weight polymers can be estimated by laser mass spectrometry. The order of monomer addition can be estimated by measuring three-carbon fragment ions in polyvinylidene fluoride. The value of SIMS for studying surface reactions is reviewed. Detection of surface impurities on polymer surfaces is possible using the laser microprobe LAMMA-1000. The specific example discussed involves detecting dye molecules on polystyrenes.

Polymerization of pyromellitic dianhydride with 3,3′‐diaminobenzidine in aprotic solvents I. Reaction variables

AbstractThe solution polymerization of pyromellitic dianhydride with 3,3′‐diaminobenzidine to form poly(amide acid amine) was investigated under a variety of reaction conditions. Polymer viscosity and gel formation were highly affected by changes in the order of monomer addition, the type of process (powder or solution), monomer concentration, monomer stoichiometry, and type of solvent. Minor effects were noted with changes in polymerization temperature and the presence of small amounts of water. A limiting intrinsic viscosity of 1.2–1.5 dl/g was observed, regardless of polymerization conditions. The polymerization had a strong tendency to gel at high concentrations and when monomer molar ratios approached 1:1. The conditions which retarded or promoted the formation of macrogel were well‐defined, and macrogel but not microgel could be prevented. The polymerization was conducted successfully only in aprotic solvents. No imidazopyrrol‐one units were detected in polymer made in polyphosphoric acid at elevated temperatures.