Aliphatic
poly(H-phosphonate)s were obtained by polyesterification of dimethyl
H-phosphonate with bio-based long-chain diols. Nonadecane-1,19-diol,
tricosane-1,23-diol, and octatetracontane-1,48-diol with dimethyl
H-phosphonate yield the corresponding polyphosphoesters (PPE19H, PPE23H, and PPE48H) with molecular weights
(M
n) up to 4.3 × 104 g
mol–1. Postfunctionalization of these polymers via
Hirao cross-coupling yields the selectively functionalized
poly(H-phosphonate)s PPE19Ph, PPE23Ph, and PPE48Ph. DSC analysis revealed significantly enhanced
crystallinities and melting points (up to T
m = 110 °C) with increasing methylene sequence lengths. Hydrolytic
degradation of polymer powder of poly-(H-phosphonate) occurred up to
95% in 2 days. The degradation rates decreased with increasing methylene
sequence length. After postfunctionalization, degradation occurred
only to a minimal extent over 3 months in basic and in acidic media.
In this contribution, two couples of cationic enantiomeric complexes [(R,R)-[LnL]Cl and (S,S)-[LnL]Cl, with Ln = Sm and Eu and L = N, N’-bis(2-pyridylmethyl)- 1,2-(R,R or S,S)-cyclohexanediamine functionalized at sp3 N...
Synthetic polymers are mixtures of chains with different
lengths,
and their chain length and chain conformation are often experimentally
characterized by ensemble averages. We demonstrate that double electron–electron
resonance (DEER) spectroscopy can reveal the chain length distribution
and the chain conformation and flexibility of the individual n-mers in oligo-(9,9-dioctylfluorene) from controlled Suzuki–Miyaura
coupling polymerization. The required spin-labeled chain ends were
introduced efficiently via a TEMPO-substituted initiator and chain-terminating
agent, respectively, with an in situ catalyst system. Individual precise
chain length oligomers as reference materials were obtained by a stepwise
approach. Chain length distribution, chain conformation, and flexibility
can also be accessed within poly(fluorene) nanoparticles.
The self-assembly of alkaline earth carbonates in the presence of silica at high pH leads to a unique class of composite materials displaying a broad variety of self-assembled superstructures with complex morphologies. A detailed understanding of the formation process of these purely inorganic architectures is crucial for their implications in the context of primitive life detection as well as for their use in the synthesis of advanced biomimetic materials. Recently, great efforts have been made to gain insight into the molecular mechanisms driving self-assembly in these systems, resulting in a consistent model for morphogenesis at ambient conditions. In the present work, we build on this knowledge and investigate the influence of temperature, supersaturation, and an added multivalent cation as parameters by which the shape of the forming superstructures can be controlled. In particular, we focus on trumpet-and coral-like structures which quantitatively replace the well-characterised sheets and worm-like braids at elevated temperature and in the presence of additional ions, respectively. The observed morphological changes are discussed in light of the recently proposed formation mechanism with the aim to ultimately understand and control the major physicochemical factors governing the self-assembly process.Minerals 2018, 8, 75 2 of 12 similar structures can also be obtained with other carbonates, including orthorhombic analogues like strontianite (SrCO 3 ) [8,9] or aragonite (CaCO 3 ) [10][11][12].Minerals 2017, 7, 75 2 of 11 evidence that similar structures can also be obtained with other carbonates, including orthorhombic analogues like strontianite (SrCO3) [8,9] or aragonite (CaCO3) [10][11][12].
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.