A Simple and Versatile Method for the Construction of Nearly Ideal Polymer Networks

Abstract

Polymer networks usually contain numerous inhomogeneities that deteriorate their physical properties and should be eliminated to create reliable,h igh-performance materials.Asimple method is introduced for the production of nearly ideal networks from various vinyl polymers through controlled polymerization and subsequent crosslinking.M onodisperse star polymers with bromide end groups were synthesized by atom-transfer radical polymerization and endlinked with dithiol linkers using thiol-bromide chemistry.This simple procedure formed nearly ideal polymer networks,a s revealed from elasticity of the formed gel and model conjugation reactions involving linear polymers.The versatility of this method was demonstrated by preparing networks of common vinyl polymers,i ncluding polyacrylates,p olymethacrylate,a nd polystyrene.T his method can be used to prepare multiple functional nearly ideal gels and elastomers and to explore fundamental aspects of polymer networks.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Facile regulation of the electro‐optical properties of liquid crystal gels by kinetics‐controlled hierarchy self‐assembly

“…Both of the gels present identical hexagonal columnar packing with a similar column diameter of 28.7 and 29.1 Å, respectively (details in Table 1). In consideration of the formation mechanism of the physical gel that gelators self‐assemble into the primary fibers first and then gelation occurs based on the intertwined 3D fiber networks, 28,29 we speculate that the differences between the two gels exist on a fiber scale. Besides, the theory about kinetics‐controlled hierarchy self‐assembly tells us that a slow cooling rate helps to cross the energy barrier and form a more advanced organization, 22–24 i.e.…”

Linking microscopic structural changes and macroscopic mechanical responses in a near-ideal bottlebrush elastomer under uniaxial deformation

“…11 The star PnBA used for synthesizing N and G was prepared according to our previous report. 14 The detailed synthetic procedure and the characterization data are found in the ESI † (Section S1, ESI †). Table 1 summarizes the molecular characterization of the star polymers and the corresponding networks, including the polymer weight fraction (w p ), polymer volume fraction (j p ), and number density of the star polymer module (c star ).…”

Star polymer networks: a toolbox for cross-linked polymers with controlled structure

“…ATRP involves alkyl halides as dormant species, which can be directly used as the active site for the thiol-halide reaction. 180 Our group synthesized various bromide-terminated star polymers by ATRP and end-linked them with a low-molar-mass dithiol linker in the presence of an organic base 181 (Fig. 10b).…”

“…However, it led to no gelation when 4f-PS-Br (PS = polystyrene) or 4f-PMMA-Br (PMMA = poly(methyl methacrylate)) was used, suggesting low reaction efficiency in these systems. The low efficiency was attributed to 181 For some vinyl polymers, such as PMMA and PS, an additional step to append a nBA oligomer block was necessary. (c, d) SPNs bearing various hydrogen-bonding groups developed by our group.…”

“…Many types of polymers have been synthesized by ATRP and used to construct SPNs: poly(tert-butyl acrylate) (PtBA) by Johnson and coworkers 175,277 (section 3.4; Fig. 9c) as well as by Oshima and coworkers; 150,151,278 poly(methyl acrylate) (PMA) by Oshima and Mitsukami; 151 poly(n-butyl acrylate) (PnBA) by Honda and coworkers 255,262 (section 4.5); poly(N-isopropylacrylamide) (PNIPAAm) by Matsumoto and coworkers; 279 PnBA, poly(4hydroxybutyl)acrylate (PHBA), poly(methyl methacrylate) (PMMA), and polystyrene (PS) by our group 181,182 (section 3.5; Fig. 10b and c); and PNIPAAm by Okaya and coworkers 95 (section 3.1).…”