Synthesis and self-assembly behaviors of well-defined poly(lauryl methacrylate)-block-poly[N-(2-methacryloylxyethyl)pyrrolidone] copolymers

Morphology and Emulsification of Poly(N-2-(methacryloyloxy) ethyl pyrrolidone)-b-poly(benzyl methacrylate) Assemblies by Polymerization-Induced Self-Assembly

In this work, a series of amphiphilic diblock copolymers poly(N-2-(methacryloyloxy) ethyl pyrrolidone)-b-poly(benzyl methacrylate) (PNMP m -b-PBzMA n ) were developed by the dispersion polymerization method in ethanol. The polymerization-induced self-assembly (PISA) behaviors were studied systematically, and a comprehensive structure-property relationship was also established. Two distinct PISA tendencies were observed, which was mainly depended on the polymerization degree m of PNMP segment. When m is small such as 39 and 55, morphological transitions from spherical to vesicle-like assemblies via wormlike ones upon increasing n commonly happen regardless of the solid content. Alternatively, spherical assemblies became the sole morphology for PNMP64-b-PBzMA n block copolymers because of the excellent solvophilicity of the PNMP64 segment. Attributing to the amphiphilicity of PNMP m -b-PBzMA n block copolymers, PNMP m -b-PBzMA n assemblies by PISA are a type of excellent Pickering emulsifiers. These assemblies prefer to stabilize O/W Pickering emulsions as confirmed by the confocal laser scanning microscopy method, and the effects of polymerization degree of PBzMA segment or morphologies of PNMP m -b-PBzMA n assemblies are finite.

RAFT dispersion polymerisation of lauryl methacrylate in ethanol–water binary mixtures: synthesis of diblock copolymer vesicles with deformable membranes

Diblock copolymer vesicles with deformable membranes are prepared via RAFT dispersion polymerisation of lauryl methacrylate in an 80 : 20 w/w ethanol–water mixture; visible light irradiation allows facile RAFT chain-end removal from these nano-objects.

End-group ionisation enables the use of poly(N-(2-methacryloyloxy)ethyl pyrrolidone) as an electrosteric stabiliser block for polymerisation-induced self-assembly in aqueous media

End-group ionisation enables use of PNMEP as a steric stabiliser in aqueous PISA: colloidal stability depends on solution pH, with flocculation occurring below pH 4.5.

Thermoresponsive Pyrrolidone Block Copolymer Organogels from 3D Micellar Networks

A new series of amphiphilic pyrrolidone diblock copolymers poly[N-(2-methacrylaoyxyethyl)pyrrolidone]-block-poly(methyl methacrylate) (PNMP m -b-PMMA n ; where m is fixed at 37 and n is varied from 45 to 378) is developed. Spontaneously situ-gelling behaviors are observed in isopropanol when n varies from 117 to 230, whereas only dissolution or precipitation appears when n is beyond this region. Further analysis reveals that uniform thermoinduced reversible gel-sol transitions are observed in those organogels, which is attributed to the disassembly from micellar networks to micelles as confirmed by electron microscopy and other techniques. The gel-sol transition temperature is highly dependent on n and increases as n increases. Conformational interactions analyzed using 1H NMR and 2D Noesy NMR suggest that the thermoinduced stretch of solvophilic PNMP segments within micelles and the sequencing variation in the isopropanol molecules are the major cause of the gel-sol transitions.

ABx-type amphiphilic macromonomer-based supramolecular hyperbranched polymers for controllable self-assembly

A novel supramolecular hyperbranched polymer (SHP) is constructed through using an AB_x-type amphiphilic macromonomer. The obtained SHP can form ellipsoidal unimolecular micelles and branched aggregates under different solution conditions.

RAFT Aqueous Dispersion Polymerization of N-(2-(Methacryloyloxy)ethyl)pyrrolidone: A Convenient Low Viscosity Route to High Molecular Weight Water-Soluble Copolymers

RAFT solution polymerization of N-(2-(methacryoyloxy)ethyl)pyrrolidone (NMEP) in ethanol at 70 °C was conducted to produce a series of PNMEP homopolymers with mean degrees of polymerization (DP) varying from 31 to 467. Turbidimetry was used to assess their inverse temperature solubility behavior in dilute aqueous solution, with an LCST of approximately 55 °C being observed in the high molecular weight limit. Then a poly(glycerol monomethacylate) (PGMA) macro-CTA with a mean DP of 63 was chain-extended with NMEP using a RAFT aqueous dispersion polymerization formulation at 70 °C. The target PNMEP DP was systematically varied from 100 up to 6000 to generate a series of PGMA63-PNMEP x diblock copolymers. High conversions (≥92%) could be achieved when targeting up to x = 5000. GPC analysis confirmed high blocking efficiencies and a linear evolution in Mn with increasing PNMEP DP. A gradual increase in Mw/Mn was also observed when targeting higher DPs. However, this problem could be minimized (Mw/Mn < 1.50) by utilizing a higher purity grade of NMEP (98% vs 96%). This suggests that the broader molecular weight distributions observed at higher DPs are simply the result of a dimethacrylate impurity causing light branching, rather than an intrinsic side reaction such as chain transfer to polymer. Kinetic studies confirmed that the RAFT aqueous dispersion polymerization of NMEP was approximately four times faster than the RAFT solution polymerization of NMEP in ethanol when targeting the same DP in each case. This is perhaps surprising because both 1H NMR and SAXS studies indicate that the core-forming PNMEP chains remain relatively solvated at 70 °C in the latter formulation. Moreover, dissolution of the initial PGMA63-PNMEP x particles occurs on cooling from 70 to 20 °C as the PNMEP block passes through its LCST. Hence this RAFT aqueous dispersion polymerization formulation offers an efficient route to a high molecular weight water-soluble polymer in a rather convenient low-viscosity form. Finally, the relatively expensive PGMA macro-CTA was replaced with a poly(methacrylic acid) (PMAA) macro-CTA. High conversions were also achieved for PMAA85-PNMEP x diblock copolymers prepared via RAFT aqueous dispersion polymerization for x ≤ 4000. Again, better control was achieved when using the 98% purity NMEP monomer in such syntheses.