Hydration Bonding System – Attractive and Repulsive Hydration Forces,
SCHL (Structure Change in Hydration Layers) theory
as most important phenomenon in supra- and hypermolecular chemistry
An increased interest has witnessed in hypermolecular research and application the past 10 years, sparked mostly by technological interests in new and renewable materials on biological basis or similar to biological system and more environmentally friendly and sustainable resources. We are living in era of nanotechnologies, bioengineering, biomaterials, biomanipulation, biopolymers, bioacceptability, biocompatibility etc. The mankind interest has been step by step concentrated into engineering of macro-objects (mechanical engineering) then micro-objects (micro-engineering) and now in nano-objects (nano-engineering) - the world of molecules. Typical nano-world upon highest sophisticated level with endless self-organization and reproducible abilities are living organism – the bio-objects. The bio-world is traditionally environment where we are living. The mankind step by step has researched this bio-world because of the existence reasons. Firstly it is classification of bio-objects, secondly a deeply explanation of their behaviour and thirdly a mechanism of this behaviour on molecular level followed by aim to bioengineered of them.
The bio-objects are composed by two basic biopolymers:
cellulose (relative simple polymer, non-moveable bio-objects, e.g. one-year plants, tries etc.)
polypeptides (complicated scale of polymers, moveable bio-objects, e.g. animals etc.)
The hydrogen bond is very important in biological systems and for existence of life but presence of water molecules are most pre-requisite for its creation. The creation of hydrogen bond is perhaps the most essential type of bond from the papermaker’s point of view.
A lot of unambiguous evidences is known that without water the bio-objects could not be existed and function, however, without the liquid water. The water molecules play a key role in existence of the bio-objects. Without water are no life and no products of life processes. The biopolymers are self-connected with water into hydrogel discontinuities of different consistencies, size, structure and shape forming so the whole body of bio-object. Terms as immobilised water, vicinal water or non-soluble water are connected with this behaviour and the properties of biomaterials. However, the behaviour of mostly bio-objects and other water-based systems we are not be able satisfactory to explain by use of these terms.
For instance, the basic phenomena can be demonstrated as
a connectivity between hydrogen bonding system in paper and paper products and the key role of water during its creation (milled pulp, i.e. refined pulp in dry state has no bonding abilities controversy to beated pulp, i.e. refined pulp in wet state)
atypical behaviour of special urea-formaldehyde pre-condensate system during dilution with water (hydrophilic water systems which in concentrated state form optically homogeneous system but getting turbid in diluted state)
atypical very interestingly behaviour of high-concentrated homogeneous transparency water system as sodium acetate, honing etc. and called as Super molecular liquid – crystallised state transition which by contact with microcrystal of this one only a crystallisation of the whole system is triggered
biomimetic systems especially muscles movement although recently electroactive cellulose biomimetic sensor/actuator termed artificial muscles due to their operational similarity to biological muscles was described (Kim J., Yun S., Ounaies Z.: Discovery of Cellulose as a Smart Material, Macromolecules 2006, 39, 4202-4206) but with traditionally irrationally explanation of mechanism of their behaviour based on unrealistic relative slowly migration of sodium ions
atypical temperature and composition influence upon rheology of aqueous glues and coating colours distinguishing by existence of peaks upon viscosity – temperature curves
For further development of our knowledge it is crucial to ascertain a mechanism responsible for the performance phenomena mentioned above.
Figure 1 - Schematically representation the concept of immobilised water and hydration bonding system
The basic orientation of water molecules in vicinity of nano-locality interfaces with:
- Proton-Donor activity D <
It is no problem to explain satisfactory all of these challenged questions by use of SCHL theory, the concept of hydration bonding system applied in supramolecular and hypermolecular water systems and practical aspects and behaviour of real highly concentrated water systems inclusive. Figure 1 shows schematically the main concept of SCHL theory. Dipole character of water molecule controls its orientation around hydrophilic interface composed with proton-acceptor (A) and proton-donor (D) groups. Due to this fact, different basic orientations of vicinal water molecules around nano-localities of hydrophilic interface are evoked with more and more diffusion character at higher distance. Theoretically, the disappeared distance, i.e. where this oriented structure disappears and is even with bulk of water, is approximately 30 – 80 nm. Logically, mutually interaction of nano-surfaces (depicted in Figure 1) with the same orientation of water molecules are complied with repulsive hydration forces characterized by high tendency to disturb this orientation. By virtually shift of the interfaces depicted at Figure 1, the attractive hydration forces eventually stabile hydration bonding system are evoked, i.e. the attractive hydration forces are prevailed the repulsive ones. The action of hydration forces is strongly influenced by temperature – with increasing temperature the both attractive and repulsive forces decrease but distance of their action increases. Interestingly, at comparable conditions, i.e. predominantly constant interfaces only differentiated with opposite activities of nano-localities and temperature, the distance of repulsive forces action is longer than for the attractive ones.