Structural Studies of Nanophase-Separated Poly(2-hydroxyethyl methacrylate)-l-polyisobutylene Amphiphilic Conetworks by Solid-State NMR and Small-Angle X-ray Scattering

Abstract

Bicomponent nanophase-separated poly(2-hydroxyethyl methacrylate)-linked-polyisobutylene (PHEMA-l-PIB) amphiphilic conetworks were synthesized by radical copolymerization of methacrylate−telechelic polyisobutylene (MA−PIB−MA) and different amounts of 2-(trimethylsilyloxy)ethyl methacrylate (SEMA) followed by quantitative hydrolysis of the trimethylsilyl protecting groups. The PIB content of the resulting conetworks, determined by elemental analysis and solid-state 1H NMR under fast magic-angle spinning (MAS), varied between 17 and 63% w/w. Phase separation and morphology of these conetworks were investigated by DSC, small-angle X-ray scattering (SAXS), and for the first time by 1H spin diffusion solid-state NMR. Two T g values were observed by DSC in all samples. The observed T g values were close to the literature values of both homopolymers (110 °C for PHEMA and −67 °C for PIB), indicating a strong phase-separated morphology in these conetworks. Parameters were optimized for the 1H spin diffusion NMR experiments, and the measurements were carried out with six filtering cycles and a 10 μs delay between pulses at 90 °C. The NMR and SAXS measurements prove strong phase-separated morphology. The sizes of the hydrophilic (PHEMA) and hydrophobic (PIB) nanodomains were determined to be in the 5−15 nm range. The spin diffusion experiments also indicate strongly separated phases without a detectable interface with mixed components. The long period of our system seems to depend weakly on the volume fraction whereas the morphology of the nanophases depends on the volume fraction.

Timescales of self-healing in human bone tissue and polymeric ionic liquids

“…Whereas ILs are usually salts with a melting point below 100°C, POILs are usually solids. Besides polymeric chains, POILS contain bulky organic cations such as imidazolium, pyridinium, ammonium or phosphium cations [18][19][20][21] together with organic and inorganic anions. Heat treatment of POILS destroys their long-range order, and we study the kinetics of subsequent self-healing.…”

Preparation of highly branched polyethylene using (α‐diimine) nickel complex covalently supported on modified SiO2

“…Amphiphilic conetworks (APCNs) composed of chemically bonded hydrophilic and hydrophobic polymer chains have gained significant interest in recent years (see, e.g., refs 1–26. and references therein).…”

Fast Synthesis of Nanostructured Microspheres of a Bridged Silsesquioxane via Ultrasound‐Assisted Sol–Gel Processing

“…The series 1:H3:2:H7:3:H12... among diffracted peaks is characteristic of a two-dimensional hexagonal structure consisting of cylindrical self-assemblies crystallized in a hexagonal lattice (Figure 7). [48,49] On this basis, we assigned the most intense peak (0.38 Å À1 ), the second one (0.66 Å À1 ) and the small shoulder to the first, second, and third Bragg reflections in accordance to the 2D-hexagonal structure.…”