Anomalous Swelling Behavior of Poly(N-vinylimidazole)-l-Poly(tetrahydrofuran) Amphiphilic Conetwork in Water Studied by Solid-State NMR and Positron Annihilation Lifetime Spectroscopy

Nanoconfined Crosslinked Poly(ionic liquid)s with Unprecedented Selective Swelling Properties Obtained by Alkylation in Nanophase-Separated Poly(1-vinylimidazole)-l-poly(tetrahydrofuran) Conetworks

Despite the great interest in nanoconfined materials nowadays, nanocompartmentalized poly(ionic liquid)s (PILs) have been rarely investigated so far. Herein, we report on the successful alkylation of poly(1-vinylimidazole) with methyl iodide in bicontinuous nanophasic poly(1-vinylimidazole)-l-poly(tetrahydrofuran) (PVIm-l-PTHF) amphiphilic conetworks (APCNs) to obtain nanoconfined methylated PVImMe-l-PTHF poly(ionic liquid) conetworks (PIL-CNs). A high extent of alkylation (~95%) was achieved via a simple alkylation process with MeI at room temperature. This does not destroy the bicontinuous nanophasic morphology as proved by SAXS and AFM, and PIL-CNs with 15-20 nm d-spacing and poly(3-methyl-1-vinylimidazolium iodide) PIL nanophases with average domain sizes of 8.2-8.4 nm are formed. Unexpectedly, while the swelling capacity of the PIL-CN dramatically increases in aprotic polar solvents, such as DMF, NMP, and DMSO, reaching higher than 1000% superabsorbent swelling degrees, the equilibrium swelling degrees decrease in even highly polar protic (hydrophilic) solvents, like water and methanol. An unprecedented Gaussian-type relationship was found between the ratios of the swelling degrees versus the polarity index, indicating increased swelling for the nanoconfined PVImMe-l-PTHF PIL-CNs in solvents with a polarity index between ~6 and 9.5. In addition to the nanoconfined structural features, the unique selective superabsorbent swelling behavior of the PIL-CNs can also be utilized in various application fields.

Synthesis and properties of a temperature-sensitive hydrogel based on physical crosslinking via stereocomplexation of PLLA-PDLA

A synthetic route to amphiphilic conetwork (APCN) gels was developed and involved (1) a ring-opening polymerization (ROP) synthesis of the macromonomer HEMA-PLLA/PDLA, and (2) a radical polymerization of a stereocomplex of the synthesized macromonomers with P(MEO₂MA-co-OEGMA) to form the APCN gels. The structure of the gel was successfully verified using X-ray diffraction. Thermal analysis and differential scanning calorimetry data showed that the thermal behaviors of the gels were greatly improved compared with that of polylactic acid (PLA). The mechanical properties of the gels were measured by using a dynamic viscometer, and the results indicated a greater mechanical strength before swelling than afterwards, and an increasing strength of the gels with increasing amount of PLA stereocomplex. Gels placed in different aqueous phases at different temperatures showed different swelling ratio (SR) values. Specifically, the SR gradually decreased as the temperature was increased, indicating a temperature sensitivity of the gels. In addition, the gels placed in the aqueous and organic phases presented as hydrogels and hydrophobic gels, respectively, and their SR values were relatively low. These results indicated the amphiphilic nature of the gel, and indicated great application prospects for the gel in biomedicine.

A synthetic route to amphiphilic conetwork (APCN) gels was developed and involved (1) ring-opening polymerization synthesis of the macromonomer, and (2) radical polymerization of stereocomplex of the synthesized macromonomers with MEO₂MA, OEGMA to form the APCN gels.

Facile synthesis of well-controlled poly(1-vinyl imidazole) by the RAFT process

Synthesis of well-controlled poly(1-vinyl imidazole).

Nanophasic morphologies as a function of the composition and molecular weight of the macromolecular cross-linker in poly(N-vinylimidazole)-l-poly(tetrahydrofuran) amphiphilic conetworks: bicontinuous domain structure in broad composition ranges

Compositionally asymmetrical morphologies and cocontinous nanophase-separated structures are formed over a broad composition range, affected by composition and the molecular weights of macromonomers.

Poly(N-vinylimidazole)-l-poly(propylene glycol) amphiphilic conetworks and gels: molecularly forced blends of incompatible polymers with single glass transition temperatures of unusual dependence on the composition

New molecularly forced blends of incompatible poly(N-vinylimidazole) and poly(propylene glycol) polymers with single glass transition temperatures.

Synthesis and Selective Loading of Polyhydroxyethyl Methacrylate-l-Polysulfone Amphiphilic Polymer Conetworks

Polyhydroxyethyl methacrylate-linked by-polysulfone amphiphilic polymer conetworks of two types of segments with T_g above room temperature are presented. The conetworks are prepared by free radical copolymerization of methacryloyl-terminated PSU macromers with 2-ethyl methacrylate, followed by removal of the TMS protecting groups by acidic hydrolysis. Phase separation in the nanometer range due to the immiscibility of the two covalently linked segments is observed using transmission electron and scanning force microscopy. The swelling of the conetworks in water and methanol as polar solvents and chloroform as nonpolar solvent are studied gravimetrically and then in a more detailed fashion by solid-state NMR spectroscopy. Selective swelling and also targeted loading of a small organic model compound specifically to one of the two phases are demonstrated.

pH sensitive amphiphilic conetworks based on end-group cross-linking of polydimethylsiloxane pentablock copolymer and polymethylhydrosiloxane

A series of pH-responsive amphiphilic conetworks were synthesized through cross-linking of well-defined amphiphilic pentablock copolymers via atom transfer radical polymerization.

Unexpected thermal decomposition behavior of poly(N-vinylimidazole)-l-poly(tetrahydrofuran) amphiphilic conetworks, a class of chemically forced blends

The underlying chemical processes of the unexpected thermal decomposition behavior of poly(N-vinylimidazole)-l-poly(tetrahydrofuran) amphiphilic conetworks were investigated by thermogravimetric analysis and thermogravimetry-mass spectrometry.

"Near perfect" amphiphilic conetwork based on end-group cross-linking of polydimethylsiloxane triblock copolymer via atom transfer radical polymerization

Novel amphiphilic conetworks (APCNs) with uniform channel size were synthesized through end-cross-linking of well-defined amphiphilic triblock copolymers via atom transfer radical polymerization (ATRP). A new ditelechelic polydimethylsiloxane macroinitiator was synthesized to initiate the polymerization of N,N-dimethylacrylamide. The resulting triblock copolymers show well-defined molecular weight with narrow polydisperisty, which are telechelic modified by allylamine and fully cross-linked with polyhydrosiloxanes through hydrosilylation. Transmission electron microscopy shows that the APCN has the behavior of microphase separation with small channel size and uniform phase domain. The resulting APCNs with idealized microstructure exhibit a combination of excellent properties, i.e., superhigh mechanical strength (4 ± 1 MPa) and elongation ratio (175 ± 25%), outstanding oxygen permeability (350 ± 150 barrers), a high water uptake property, and excellent biocompatibility, indicating that in this way, "near perfect" networks are obtained. These results are better than those reported in the literature, suggesting a promising semipermeable barrier for islet encapsulation in relative biomaterial fields.