Ouzo phase occurrence with alternating lipo/hydrophilic copolymers in water.

Selection of monomer couples, ensuring reactivity ratios close to zero, is an effective strategy to induce spontaneous copolymerization into an alternating sequence. In addition, monomer design and customisation of the solvent-monomer interactions open the way to functional copolymers showing molecular self-assembly relevant to their regular amphipathic structure. In this work, we show that the design of comonomers with adequate reactivities and interactions can be used to direct copolymer self-assembly on a mesoscopic scale. We investigate spontaneous formation of nanoparticles through solvent/non-solvent interactions using the so-called "ouzo effect". In this way, an ouzo diagram was built to determine the operation window for the self-assembly, in aqueous suspensions, of alternating copolymers consisting of vinyl phenol and maleimide units carrying long alkyl-pendant groups (C12H25 or C18H37). Also, investigations were pursued to account for the influence of the lateral lipophilic pendant units on the size and structure of the nanoaggregates formed during one-shot water addition. Structure characterisation by light scattering techniques (DLS and SLS), small-angle neutron scattering (SANS) and transmission electron microscopy (cryo-TEM and TEM) confirmed the self-assembly of copolymer chains into nanoparticles (size range: 60-300 nm), the size of which is affected by the lipophilicity of the alternating copolymers, solvent-water affinity and the solvent diffusion in water. Altogether, we present here the spontaneous ouzo effect as a simple method to produce stable alternating copolymer nanoparticles in water without the addition of stabilizing agents.

AB-alternating copolymers via chain-growth polymerization: synthesis, characterization, self-assembly, and functions.

An AB-alternating copolymer is distinctly unique in comparison with other copolymers (e.g., random, gradient, and block) because the structure is uniform in terms of sequence: there is no composition distribution among the chains, and there are no consecutive sequence such as AA or AAA in one chain. Various types of alternating copolymers have been synthesized via strategic monomer design and advanced control of the copolymerization process. They exhibit the unique self-assembly behaviors and properties derived from the sequence, which are different from random or block copolymers in some cases. In this review, four topics related to alternating copolymers synthesized via chain-growth polymerization are reviewed: (1) how to control the alternating sequence; (2) sequence characterization; (3) self-assembly; and (4) functions.

Sequence Analysis for Alternating Copolymers by MALDI-TOF-MS: Importance of Initiator Selectivity for Comonomer Pair.

A special initiator for metal-catalyzed living radical polymerization facilitates sequence analyses by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) of alternating copolymers from styrene and maleimide derivatives. The initiator is a malonate-based alkyl halide (DEMM-Br), in which two ester groups are attached on the carbon neighboring to bromide, and poor electron density of the radical species allows determination of next unit to the initiator in resultant alternating copolymers due to the selective initiation to styrene derivative. Thanks to the well-defined α-end group, sequence of the oligomeric products via radical copolymerization of PMS and EMI with DEMM-Br can be more simply analyzed by MALDI-TOF-MS, and indeed the following are clarified: the crossover propagation is almost perfectly controlled regardless of the injection ratio; a minor error event of the disordered alternating sequence containing St-St sequential unit could take place; the minor error can be suppressed with an excess amount of maleimide.