To address the challenge of controllable and precise regulation of the phase behavior of block copolymers, this study proposes a novel strategy to regulate the self-organization behavior of PS-P2VP block copolymers through supramolecular self-assembly. PS-P2VP was synthesized via the RAFT method, and three POSS molecules with different non-covalent interactions were synthesized and used to form complexes with the PS-P2VP copolymers. Characterization techniques such as NMR, GPC, FT-IR, TGA, DSC, SAXS, and SEM, along with theoretical methods, were employed to analyze the impact of POSS on the phase behavior of PS-P2VP. The results demonstrate that POSS is particularly effective in modulating the self-assembled phase behavior in the lamellar phase of block copolymers, with BPOSS-Cl showing the most significant modulation, enabling the complexes to achieve third-order peaks in SAXS measurements. This conclusion is further supported by theoretical calculations. The study not only reveals the mechanism by which POSS regulates the self-assembly behavior of PS-P2VP but also provides a promising direction for advancing autonomous phase selection in block copolymers.
Poly(N-isopropylacrylamide) (PNIPAM) chain with catechol end group was designed and successfully synthesized by a reversible addition–fragmentation chain transfer (RAFT) procedure, and then, even via a simple one-step soaking method, it could be firmly grafted to many different substrates (e.g., a stainless-steel mesh, a nylon microfiltration membrane, an Al plate, and glass). Moreover, after the end anchoring, the formed thin and uniform coating of PNIPAM onto the surfaces of the stainless-steel mesh and the nylon microfiltration membrane would endow the surfaces with a valuable thermo-driven controllable separation ability for oil–water mixtures and emulsions, respectively. And below PNIPAM’s lower critical solution temperature (LCST) (34 °C), the membranes exhibited hydrophilicity and underwater oleophobicity and thus can be used for the separation of a “light oil”/water mixture and an O/W emulsion through a “removing water” process; meanwhile, above its LCST, the membranes show the opposite properties (hydrophobicity and oleophilicity) and thus are used to separate a “heavy oil”/water mixture and a W/O emulsion through a “removing oil” process. In addition, without changing the morphologies and pore sizes of the substrates, the membranes gave many excellent performances such as excellent recyclability, high separation efficiency and a thermo-driven controllable separation ability. So, the facile and effective strategy presented in this work that is suitable for the coupling of PNIPAM with various substrates would also supply an inspiration to the effect conjunction for heterogeneous materials of other functional polymers and substrates.
The thermo- and pH/CO2-responsive poly[N-[2-(dialkylamino)ethyl]acrylamide]s containing a polyacrylamide backbone but different N-substitutes of dialkylamine were synthesized and their solution properties were comparatively checked. A controllable RAFT synthesis of poly[N-[2-(dialkylamino)ethyl]acrylamide]s was achieved when a typical trithiocarbonate containing an easily cleavable R group was employed. The RAFT polymerization rate decreases with the increasing C-number in the N-substitutes. The thermo- and pH/CO2-responsive property of poly[N-[2-(dialkylamino)ethyl]acrylamide]s is firmly correlative to the N-substitutes. With the C-number in the R-substitute increasing, the solution properties of poly(N-[2-(dialkylamino)ethyl]acrylamide)s undergo a soluble-to-thermoresponsive-to-insoluble evolution, and the critical pH of poly[N-[2-(dialkylamino)ethyl]acrylamide]s gradually decreases. The dialkylamine moieties in the poly[N-[2-(dialkylamino)ethyl]acrylamide]s lead to a characteristic CO2-response during CO2/N2 bubbling. The present study reveals the structure-dependent solution properties of the thermo- and pH/CO2-responsive poly[N-[2-(dialkylamino)ethyl]acrylamide]s, and these multistimuli-responsive polymers are believed to be very useful due to the controllable RAFT synthesis and tunable solution properties.
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