A novel class of bolapolyphile (BP) molecules are shown to integrate into phospholipid bilayers and self-assemble into unique sixfold symmetric domains of snowflake-like dendritic shapes. The BPs comprise three philicities: a lipophilic, rigid, π–π stacking core; two flexible lipophilic side chains; and two hydrophilic, hydrogen-bonding head groups. Confocal microscopy, differential scanning calorimetry, XRD, and solid-state NMR spectroscopy confirm BP-rich domains with transmembrane-oriented BPs and three to four lipid molecules per BP. Both species remain well organized even above the main 1,2-dipalmitoyl-sn-glycero-3-phosphocholine transition. The BP molecules only dissolve in the fluid membrane above 70 °C. Structural variations of the BP demonstrate that head-group hydrogen bonding is a prerequisite for domain formation. Independent of the head group, the BPs reduce membrane corrugation. In conclusion, the BPs form nanofilaments by π stacking of aromatic cores, which reduce membrane corrugation and possibly fuse into a hexagonal network in the dendritic domains.

We investigate the molecular dynamics within the crystallites of poly(εcaprolactone), PCL, crystallized from the melt by means of high-field 13 C and low-field 1 H NMR spectroscopy, addressing the question of whether it can be classified as a "crystal-fixed" polymer without chain motion through the crystallites. We address fast, slow, and intermediateregime (microseconds to milliseconds time scale) motions by means of high-resolution of 13 C DIPSHIFT and CODEX MAS experiments as well as low-resolution static 1 H FID and MSE measurements over a range of temperatures. The DIPSHIFT data provide information on motionally averaged 13 C− 1 H dipole−dipole couplings and indicate the presence of fast (≤1 μs) methylene group librational motions within the crystalline phase, where the amplitudes increase with increasing distance from the rather rigid ester groups. The CODEX experiments, addressing slow (≥ms) local rotations of the chemical-shift anisotropy tensors, suggest the absence of slow intracrystallite chain dynamics. 1 H second-moment and MSE signal loss data of the crystalline fraction, along with the DIPSHIFT and CODEX data, indicate that intermediate-regime chain motions do not take place in PCL crystallites.

Helical jumps in poly­(ethylene oxide), which are the molecular processes underlying the intracrystalline chain diffusion, are studied on the microseconds to milliseconds time scale by means of NMR. Using a simple proton time-domain technique, a wide range of melt-crystallized morphologies is investigated ranging from extended-chain crystals of short chains to crystals with disordered fold surfaces of longer chains up to 190 kg/mol. From variable-temperature data we directly determine the Arrhenius activation parameters and find that the activation energy is always around 65 kJ/mol. At a given temperature, average correlation times vary from sample to sample over about 1 decade and increase approximately linearly with the lamellar thickness. The observed linear relation is reproduced by a generic Monte Carlo simulation model implementing a mechanism of diffusing defects. The experimental results are compared to 1D carbon-13 MAS exchange NMR (CODEX) and proton rotating-frame relaxation (R 1ρ) data, for which we highlight the challenges and significant bias effects arising from the significant distribution of correlation times. Effective spin-diffusion averaging of the proton R 1ρ demonstrates that monomers with different jump dynamics are spatially close; i.e., they coexist in neighboring stems.

A novel class of rigid-rod bolapolyphilic molecules with three philicities (rigid aromatic core, mobile aliphatic side chains, polar end groups) has recently been demonstrated to incorporate into and span lipid membranes, and to exhibit a rich variety of self-organization modes, including macroscopically ordered snowflake structures with 6-fold symmetry. In order to support a structural model and to better understand the self-organization on a molecular scale, we here report on proton and carbon-13 high-resolution magic-angle spinning solid-state NMR investigations of two different bolapolyphiles (BPs) in model membranes of two different phospholipids (DPPC, DOPC). We elucidate the changes in molecular dynamics associated with three new phase transitions detected by calorimetry in composite membranes of different composition, namely, a change in π-π-packing, the melting of lipid tails associated with the superstructure, and the dissolution and onset of free rotation of the BPs. We derive dynamic order parameters associated with different H-H and C-H bond directions of the BPs, demonstrating that the aromatic cores are well packed below the final phase transition, showing only 180° flips of the phenyl ring, and that they perform free rotations with additional oscillations of the long axis when dissolved in the fluid membrane. Our data suggests that BPs not only form ordered superstructures, but also rather homogeneously dispersed π-packed filaments within the lipid gel phase, thus reducing the corrugation of large vesicles.

A novel class of symmetric amphi-and triphilic (hydrophilic, lipophilic, fluorophilic) block copolymers has been investigated with respect to their interactions with lipid membranes. The amphiphilic triblock copolymer has the structure PGMA 20 -PPO 34 -PGMA 20 (GP) and it becomes triphilic after attaching perfluoroalkyl moieties (F9) to either end which leads to F 9 -PGMA 20 -PPO 34 -PGMA 20 -F 9 (F-GP). The hydrophobic poly(propylene oxide) (PPO) block is sufficiently long to span a lipid bilayer. The poly(glycerol monomethacrylate) (PGMA) blocks have a high propensity for hydrogen bonding. The hydrophobic and lipophobic perfluoroalkyl moieties have the tendency to phase segregate in aqueous as well as in hydrocarbon environments. We performed differential scanning calorimetry (DSC) measurements on polymer bound lipid vesicles under systematic variation of the bilayer thickness, the nature of the lipid headgroup, and the polymer concentration. The vesicles were composed of phosphatidylcholines (DMPC, DPPC, DAPC, DSPC) or phosphatidylethanolamines (DMPE, DPPE, POPE). We showed that GP as well as F-GP binding have membrane stabilizing and destabilizing components.PPO and F9 blocks insert into the hydrophobic part of the membrane concomitantly with PGMA block adsorption to the lipid headgroup layer. The F9 chains act as additional membrane anchors. The insertion of the PPO blocks of both GP and F-GP could be proven by 2D-NOESY NMR spectroscopy. By fluorescence microscopy we show that F-GP binding increases the porosity of POPC giant unilamellar vesicles (GUVs), allowing the influx of water soluble dyes as well as the translocation of the complete triphilic polymer and its accumulation at the GUV surface. These results open a new route for the rational design of membrane systems with specific properties.