In this study, we report detailed information on the internal structure of PNIPAM-b-PEG-b-PNIPAM nanoparticles formed from self-assembly in aqueous solutions upon increase in temperature. NMR spectroscopy, light scattering, and small-angle neutron scattering (SANS) were used to monitor different stages of nanoparticle formation as a function of temperature, providing insight into the fundamental processes involved. The presence of PEG in a copolymer structure significantly affects the formation of nanoparticles, making their transition to occur over a broader temperature range. The crucial parameter that controls the transition is the ratio of PEG/PNIPAM. For pure PNIPAM, the transition is sharp; the higher the PEG/PNIPAM ratio results in a broader transition. This behavior is explained by different mechanisms of PNIPAM block incorporation during nanoparticle formation at different PEG/PNIPAM ratios. Contrast variation experiments using SANS show that the structure of nanoparticles above cloud point temperatures for PNIPAM-b-PEG-b-PNIPAM copolymers is drastically different from the structure of PNIPAM mesoglobules. In contrast with pure PNIPAM mesoglobules, where solidlike particles and chain network with a mesh size of 1-3 nm are present, nanoparticles formed from PNIPAM-b-PEG-b-PNIPAM copolymers have nonuniform structure with "frozen" areas interconnected by single chains in Gaussian conformation. SANS data with deuterated "invisible" PEG blocks imply that PEG is uniformly distributed inside of a nanoparticle. It is kinetically flexible PEG blocks which affect the nanoparticle formation by prevention of PNIPAM microphase separation.

Lanthanide-doped upconversion nanoparticles (UCNPs) display highly beneficial photophysical features for background-free bioimaging and bioanalysis; however, they are instable in high ionic strength buffers, have no functional groups, and are nonspecifically interacting. Here, we have prepared NIR-excitable UCNPs that are long-term colloidally stable in buffered media and possess functional groups. Heterobifunctional poly(ethylene glycol) (PEG) linkers bearing neridronate and alkyne or maleimide were attached to UCNPs via a ligand exchange. Streptavidin (SA)-

The preparation of soluble conducting polymers proceeds by the chemical oxidation method in the presence of water‐soluble polyelectrolytes. Among conducting polymers, polyethylene‐(3,4‐dioxythiophene) (PEDOT) is the most investigated due to its intrinsic properties. In this work, for the first time a simple method of ethylene‐(3,4‐dioxythiophne) self‐polymerization without applying any oxidant and with the formation of PEDOT solution at room temperature with a yield of 100% is presented. This PEDOT solution could be deposited on many desirable surfaces (by simple evaporation of the solvent) for various applications from photovoltaic cell to pseudocapacitors. Moreover, it is discovered that the self‐polymerization method does not produce byproducts, which makes the method environmentally friendly. The effect of light and different acids is explored. Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy (XPS), and Raman spectroscopy confirm the formation of PEDOT by the self‐polymerization method. Moreover, this method provides a way to obtain and study individual PEDOT chains. The self‐polymerization method may be applied for the preparation of other conducting polymers.

Nuclear magnetic resonance (NMR) lineshape analysis is a powerful tool for the study of chemical kinetics. Here we provide techniques for analysis of the relationship between experimentally observed spin kinetics (transitions between different environments $$A,B,\dots$$ A , B , ⋯ ) and corresponding chemical kinetics (transitions between distinct chemical species; e.g., free host and complexed host molecule). The advantages of using analytical solutions for two-, three- or generally N-state exchange lineshapes (without J-coupling) over the widely used numerical calculation for NMR spectral fitting are presented. Several aspects of exchange kinetics including the generalization of coalescence conditions in two-state exchange, the possibility of multiple processes between two states, and differences between equilibrium and steady-state modes are discussed. ‘Reduced equivalent schemes’ are introduced for spin kinetics containing fast-exchanging states, effectively reducing the number of exchanging states. The theoretical results have been used to analyze a host–guest system containing an oxoporphyrinogen complexed with camphorsulfonic acid and several other literature examples, including isomerization, protein kinetics, or enzymatic reactions. The theoretical treatment and experimental examples present an expansion of the systematic approach to rigorous analyses of systems with rich chemical kinetics through NMR lineshape analysis.

The standard enthalpies of combustion, formation, fusion, and sublimation of crystalline furan 2 carboxylic and 3 (2 furyl) 2 propenoic acids are determined by experimental methods and recalculated to 298 K. The possibility of using additive calculation schemes based on the principle of group contributions to calculate the standard enthalpies of vaporization and formation of substances with similar combinations of functional fragments in the gas phase is analyzed.