Block copolymers form the basis of the most ubiquitous materials such as thermoplastic elastomers, bridge interphases in polymer blends, and are fundamental for the development of high-performance materials. The driving force to further advance these materials is the accessibility of block copolymers, which have a wide variety in composition, functional group content, and precision of their structure. To advance and broaden the application of block copolymers will depend on the nature of combined segmented blocks, guided through the combination of polymerization techniques to reach a high versatility in block copolymer architecture and function. This review provides the most comprehensive overview of techniques to prepare linear block copolymers and is intended to serve as a guideline on how polymerization techniques can work together to result in desired block combinations. As the review will give an account of the relevant procedures and access areas, the sections will include orthogonal approaches or sequentially combined polymerization techniques, which increases the synthetic options for these materials.

Y The anionic ring-opening polymerizations (AROP) of bio-based N-acetyl homocysteine thiolactone (NHTL) and different epoxides were carried out using benzyl alcohol and 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine (BEMP) as initiating system. This polymerization is a rare example of AROP in the presence of an acidic moiety (acetamido group). Well-defined alternating poly(ester-alt-sulfide)s are obtained with number-average molar masses M-n ranging from 1.7 to 13.0 kg mol(-1) and dispersities as low as 1.14. The presence of one acetamido function in the lateral group on each repeating unit of the copolymers derived from NHTL results in very significant increases (up to 94 degrees C) of the glass transition temperature T-g compared to similar poly(ester-alt-sulfide) derived from petro-based gamma-butyrothiolactone (BTL). These functional poly(NHTL-alt-epoxide)s are valuable structures with numerous potential applications due to the presence in each repeating unit of one cleavable ester group and one redox-sensitive thioether group.

The copolymerization of tert-butyl glycidyl ether (tBuGE), allyl glycidyl ether (AGE), ethoxyethyl glycidyl ether (EEGE) and 1,2-epoxybutane (BO) with.-thiobutyrolactone was investigated using benzyl alcohol-phosphazene bases as initiating systems. The prepared copolymers display perfect (poly(ester-alt-sulfide)) alternating structures for all epoxide monomers as evidenced by H-1, C-13, and 2D NMR and MALDI-TOF mass spectrometry. A marked influence of the reaction temperature on the occurrence of transesterification side reactions has been evidenced. In particular, at elevated temperature, transesterification reactions led to the formation of alternating macrocycles. The choice of the phosphazene base (tBuP(4), tBuP(2), or tBuP(1)) has a strong impact on the system reactivity and on the control of the polymerization. The use of tBuP(1) led to very slow polymerization rates. The polymerization is much faster in the presence of tBuP(2) even at low temperature. The use of tBuP(4) shows an intermediate polymerization rate and enabled a good polymerization control at moderate temperatures. Finally, the synthesis of well-defined polyether-block-poly(ester-alt-sulfide) and the polymerization of a challenging substituted gamma-thiolactone were proven to be feasible.

This contribution fills the need for quantitative mechanistic and kinetic information for epoxide polymerizations catalyzed by tBuP4 phosphazene base.

ABSTRACT2,5‐Diketopiperazines (DKPs) are the smallest cyclic dipeptides found in nature with various attractive properties. In this study, we have demonstrated the successful modification of proline‐based DKPs using anionic ring‐opening polymerization (AROP) as a direct approach. Four different proline‐based DKPs with various side chains and increasing steric hindrance were used as initiating species for the polymerization of 1,2‐epoxybutane or ethoxyethyl glycidyl ether in the presence of t‐BuP4 phosphazene base. The addition of a Lewis acid, tri‐isobutyl aluminum, to the reaction mixture strongly decreased the occurrence of side reactions. Impact of the DKP side‐chain functionalities on molar mass control and dispersity was successfully evidenced. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1008–1016

Simple ionic liquids exhibit unique physical and chemicalproperties that make them very useful for deployment in electrochemicaldevices such as solvent-free electrolytes in capacitors and batteries.However, incorporating redox functionality into ionic liquidstructures opens up in situ faradaic electrochemistry which allows accessto a large array of new electrochemical applications reliant uponheterogeneous or homogenous electron-transfer processes. This paperpresents and discusses the opportunities and challenges for these typesof electro-materials across a myriad of applications by consideringexemplar quinone-functionalised ionic liquids.

The electrochemical carboxylation of a range of substituted benzophenones was studied in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid (IL, ([Bmpy] [NTf2])). As expected, the aromatic carbonyls exhibited electrochemical reversibility for the first reduction to the radical anion at potentials which were a function of the sum of their Hammett substituent constants (Sigma sigma). However, in the presence of CO2, the electrochemical reversibility was lost and positive shifts in reduction potentials were observed which were indicative of post-electron transfer chemical reaction which has been attributable to the nucleophilic radical anion/CO2 coupling reaction. Analysis of the positive potential shift a function of sweep rate (nu) indicated that the mechanism is either ECE or DISP1, or mixed ECE/DISP1. Also from the potential shift with nu, an apparent rate constant (k(app)), and a pseudo-first order rate constant (k(1)), for the coupling reaction was determined and compared to molecular solvent where the rate is over two orders of magnitude lower in IL compared to dimethylforrnamide (DMF). The low polarity of the IL compared to DMF appears to be the cause of slow kinetics. Finally, plots of k(app) vs. Sigma sigma were strictly linear indicating that IL does not preferentially interact with any of the electrogenerated radical anions thus implying that the electrocarboxylation reaction may be a useful probe of IL environments and structure on radical anion reactions.