Weak molecular interactions

Evidence for the low intermolecular forces between methyl groups in PDMS comes not only from low surface tensions but also from the lower boiling points of PDMS materials compared with those of organic materials of similar molecular weight. Noll 19) gives some useful data on this topic. The maintenance of liquid nature to unusually high molecular weights of linear PDMS polymers is a further consequence of this weak molecular interaction. 

Dunitz, J.D. (1995) Win some, lose some enthalpy-entropy compensation in weak molecular interactions. Chemistry el Biology, 2, 709-712. 

The key to CTeating a flexible framework is to utilize weak molecular interactions in addition to the strong covalent and coordination bonds. Actually, coordination bonds in PCPs are frequently supported by hydrogen bonds, n-n stacking, van der Waals forces and other weak interactions. Intermolecular links with these weaker interactions produce flexible parts in a framework, so that the system can exist in two or more sohd phases. Depending on the external perturbations and guest molecules, the systan will be in one of the multiple solid phases. 

According to the molecular component of the azo BC, the wormlike domains with a width of 25 nm should be segregated by the azo blocks, leading to the disappearance of an LC texture after microphase separation because of the limited POM resolution. The novel wormlike nanostructures might be caused by the balance between microphase separation and LC self-assembly, which makes it different from the phase-segregated morphologies of BCs with weak molecular interactions (Yu et al., 2007b). 

POM adsorption on CNTs via multiple weak molecular interactions of CH groups with CNTs has been identified using FUR and Raman spectroscopy." MWCNTs showed nucleation effect on POM, leading to an increase of the ciystalhzation temperature and the crystallization rate, and the reduction of sphemlite size. ... 

The conclusions of [83] were confirmed in [81, 84] for several liquid crystal mixtures however, (2.69) seems to be correct only for compounds (mixtures) with weak molecular interaction. 

EMR spectra correspond to transitions among the electronic Zeeman levels, subject to selection rule Amg = 1, Amj = 0 (for all rtij of the system), and it follows that these comparatively large transition energies are difficult to correlate with weak molecular interactions or subtle changes in the nuclear hyperfine energies due to substituent effects. 

Extenders are added to the polymer matrix to lower the cost of the resulting material. They are generally particulate mineral species such as carbonates, sulfates, silicates, hydroxides, and so on, that develop only weak molecular interactions with the polymer ... 

All polydienes are characterized by a high mobility of their backbone and by weak molecular interactions that explains their relatively low glass transition temperature and their incapability to crystallize spontaneously, even when their structural regularity is high. Natural rubber, which is l,4-c -polyisoprene, was discussed in Chapter 14 along with other natural polymers. 

Weak molecular interactions are another traditional area of application for explicitly correlated methods. The most taunting aspect about the calculation of interaction energies is the basis set superposition error (BSSE), i.e. the spurious extra interaction energy that is actually only the increase of pure intra-fragment correlation energy due to the overlap with basis functions from the other fragment. The BSSE vanishes for a sufficiently complete basis, which can be most efficiently achieved by explicit electron correlation, e.g. F12 methods. 

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