Research Progress on the Interaction between Polymeric Tanning Agents and Skin Collagen

The interaction model proposed by the theory further points out the development direction of this research.

Polymeric tanning agents are a class of water-dispersible polymers that interact with the collagen fibers of the skin to increase the heat-shrinking temperature of the collagen. Due to its advantages such as high molecular weight, multiple monomer types, and large active group tunability, the polymer tanning agent can not only increase the thermal contraction temperature of the collagen, but also improve the physical and chemical properties of the leather. The quality of leather, but also has a positive effect on the reduction of leather contamination, so it has been widely used in the tanning industry and has become the largest class of polymer materials in the current tanning industry. Existing polymer tanning agents are mainly acrylics. Two major categories of resin tanning agents and polyurethane tanning agents Given that collagen in skin is a natural polymer formed by the condensation of T amino acids, the interaction between polymer tanning agents and collagen in the skin can be studied from the perspective of polymer interactions. In fact, different polymer tanning agents differ in many aspects such as the monomer composition, the molecular weight of the reactive group species, and the molecular morphology, resulting in a difference in the interactions between them and the collagen. The tanning style is also very different. Therefore, studying the interaction mechanism between the polymer tanning agent and the skin collagen not only helps to select the appropriate polymer tanning agent according to the style of the desired leather, but also selects the best tanning process to make The tincture exerts the best results, and it has theoretical guidance for the development and development of better polymer tinctures in the future. It is also the theoretical basis for the “Clean Tannery” system project that has emerged in recent years to reduce environmental pollution. A. Research on the interaction between polymer tanning agents and collagen in the skin The interaction between polymer tanning agents and collagen in leather and its tanning effect is a very complicated physical chemical process. It is generally believed that the process is the penetration of macromolecular tanning agents into the raw hides. Internally, it binds its active group to the active group on the side chain of collagen, or it accumulates and precipitates in collagen fibers. Wrapped on the fiber surface to form cross-linked, adsorbed or entangled, or acted on by other methods with the collagen fibers of the skin, thus reflecting the tanning effect. It is well known that the polymer resin is characterized by the combination of the various levels of the polymer structure determines its Performance, and therefore the interaction mode and mechanism of the polymer tanning agent and the skin collagen are not only related to the chemical composition of the polymer tanning agent, but also related to factors such as the size of the molecule, the molecular form, and the arrangement of reactive groups. The basic cause of the unique tanning effect of tanning agents To study the interaction between tanning agents and collagen, we must first understand the interaction between macromolecule tanning agents and collagen in macromolecule size and even supramolecular dimension. 5 Using IRDSC X-ray diffraction, electron microscope dynamic viscoelastic spectra and other methods to study the interaction between acrylic resin tanning agent and collagen, it was pointed out that the molecular weight of the component in the polymer tanning agent and the supramolecular size of the collagen Grade fibers function to fill in the fibers, while a small amount of small molecular weight components infiltrate into the collagen fibers. Afterwards Wei Fund Project: Chinese Academy of Sciences “Light of the West” Talent Training Fund Project Jin Yong et al.: Research progress on the interaction between polymer tanning agents and collagen. Deqing et al. also used gelatin as a model compound for raw skin collagen. According to the sedimentation method, the interaction between the polymer tanning agent and gelatin was studied based on the amount of the precipitated symmetric body. The results showed that the tanning agent molecules penetrated into the collagen and formed a microenvironment between the collagen fibers. Lateral-base type Coulomb-restricted polymer molecules with smaller molecular weights permeate into the collagen fibers and undergo coulomb interaction with the collagen fibers; the other part is distributed between the collagen fibers and is deposited on the surface of the fiber by Coulomb force binding, and a part thereof is filled. Between the collagen fibers and the fiber bundles, three layers are formed: the inner layer, the middle wrap layer and the outer filling layer. The middle wrap layer is the main cross-linking material, linking the inner layer and the outer layer separated by the collagen fibers, and simultaneously spreading the fiber bundles to appropriately disperse the fiber bundles. Pan Jinsheng et al. studied vinyl polymers using various methods. After the interactions of tanning agent and skin collagen, it was pointed out that multiple forms of hydrogen bonding, electricity valence bonding, coordination cross-linking binding, and network cross-linking binding are the main modes of interaction between vinyl polymer and skin collagen. Molecular weight of polymer tanning agent The effect of its interaction with the collagen of the skin is very complicated and no clear conclusion has yet been drawn. Magei.kui.thB These people have different opinions. They believe that the molecular weight of the tincture is not necessarily related to the increase in the heat shrinkage temperature of the skin collagen. However, Anton EIA'MMA found that not only the molecular weight of the polyacrylic acid tincture molecular form , And the degree of neutralization of carboxyl groups affects the effects of tanning agent and collagen. Mizutani S et al. found in the study that poly(methacrylic acid) (PMAAc) can increase the thermal contraction temperature of the collagen, while polyacrylic acid (PAAc) There is no effect on the skin's heat shrinkage temperature. They believe that the salt formed with PAAc and collagen is poor in hydrophobicity, the steric hindrance around the Coulomb bond is small, and the carboxylate anion of PAAc in the bonding ion is easily replaced by the small molecule acid radical. This study also confirmed that the Coulomb force interaction between PMAAc and the collagen of the skin can destroy the original hydrogen bonding between the collagen fibers of the skin, thereby reducing the degree of crystallinity of the collagen. The decrease in the degree of crystallinity of the skin collagen has a significant effect on the softness of the leather. The hydrophobic effect of the methyl group on the PMAAc plays an irreplaceable role. Xu Shengyang et al. found that the anionic PU is in contact with the skin. When collagen is applied, the degree of crystallinity of the collagen in the skin can be reduced. LiY, Feah.hellei.SH. et al. used a polyacrylic acid tanning agent containing an acrylamide derivative to act on the collagen of the skin, raising the heat-shrinking temperature of the collagen to above 80 *C. 2 Polyelectrolyte interaction model due to the polymer The study of the mechanism of the interaction between the agent and the skin collagen involves the knowledge of macromolecular physical protein chemistry, polyelectrolyte theory, physical chemistry, collagen modification, chemical environmental science, and even life sciences. Therefore, this research is a very complicated multidisciplinary research. The complexity of the collagen structure, as well as the morphology and synergy of the polymer resin in the solution are also a very complex issue. The mechanism of the two at the molecular level is still unclear. The existing studies are mostly based on data obtained from experiments. One or more relevant polyelectrolytes refer to polymer interpolymer electrolytes interacting with polymer chains that have a large number of water-dissociable functional groups on the molecular chain. Science and Engineering Models The peptide chains according to the collagen are composed of T amino acids. Condensation, the fact that the side chain contains dissociable acidic and basic groups, the collagen molecule is considered as a code Type of amphoteric polyelectrolyte, and a polymeric resin tanning agent with a certain number of ionic groups in the molecular chain is also considered as a polyelectrolyte and then the interaction process between the polymer tanning agent and the collagen is attributed to the polyelectrolyte The interactions that form the polyelectrolyte complexes may be in the form of "side chain side chains" or "main chain side j chain" methods. Ionic ion interactions, ions that may exist between polyelectrolytes at the same time. Several interactions such as ion-pair interactions, ion-dipole interactions, and hydrophobic interactions are used to further explain the possible interactions between polymer tanning agents and collagen.

The determination of the polyelectrolyte characteristics of polymer tanning agent and collagen by polyelectrolyte interaction model is in line with the objective facts, and it is easy to use the theory of polymer science to study tanning chemistry from the perspective of polymer electrolyte interaction. The problem provides a new and advanced method for studying the interaction between polymer tanning agents and collagen. Wei Deqing et al. used this model to explain well the change of the solution pH value to the ligand form formed by the interaction between an anionic polyurethane tanning agent and gelatin (a model compound of skin collagen). Ma Jianzhong and others used it as a model for qualitative analysis. From the perspective of explaining the interaction between vinyl polymer resin tanning agent and leather collagen Vinklarek Z. et al. studied the effects of specific polymer tanning agents (FB) and leather collagen based on this model, and tried to use this theory to describe sulfonic acids. Base bond parameters (P) and tanning parameters (t) are quantified to obtain a polyelectrolyte complex of tanning agent FB and collagen. The condition is 蛤=P 2 (k/, K is the bond sulfonic acid per FB molecule, respectively). The number of bases and the total amount of sulfonic acid groups) 3 The development of dynamic polymer tanning agents and skin collagen interaction research, its main development trend is to combine with collagen modification chemistry in order to solve the problem of chromium pollution that has been plaguing the leather industry for many years as a light industry The tannery industry of the second largest polluters is increasingly being seen worldwide as governments and people of all countries pay more and more attention to environmental protection and various environmental protection laws and regulations are constantly put forward. How to reduce or eliminate the pollution has tannery waste chromium salts become one of the key research topics tanning industry.

Studies have shown that skin collagen generally contains about 20 amino acids, but only aspartic acid and glutamic acid carry side chain carboxyl groups. Experiments have shown that the limited number of carboxyl groups and steric hindrance, distance between phases, ionization, such as HeidemanE et al. studied the reaction of glyoxylic acid and skin collagen and the effect of the reaction on chrome tanning, and thought that aldehydes containing bifunctional aldehydes and acids Acid can theoretically reduce the amount of chromium salt used in tanning by half, which can significantly reduce the chromium salt content and environmental pollution in tanning waste liquids. However, due to the small molecule organic modification used in collagen modification research at the current stage such as glyoxylic acid. When the cost of materials and the impact on people's health are not easy to industrialize, the relevant knowledge of the interaction between polymer tanning agents and collagen is used. According to the principle of polymer design, the advantages of polymer tanning agents can carry a variety of functional groups. In combination with collagen modification chemistry, the design and synthesis of a polymer resin tanning agent containing a functional group that can be used for collagen modification, and studying the mechanistic effects of its interaction with collagen, it is undoubtedly that macromolecular tanning agents interact with collagen in the skin in the future. Content to be taken seriously for a long time.

4 Conclusion In summary, understanding the natural polymer properties of collagen, and from the perspective of polymer interactions to study the interaction between the polymer resin tanning agent and collagen, is the key to the breakthrough in this research in recent years. The interaction between molecular resin tanning agent and collagen is an important part of the study of tanning chemistry. Its significance lies not only in clarifying the mechanism of interaction between the polymer tanning agent and leather collagen, but also to propose and improve the corresponding theory. Models form a more systematic theoretical system to guide tanning production, but also to use the known research results and theoretical models to creatively design and synthesize the needs of tannery production, especially for the current tanning industry. New polymer materials that improve industrial pollution. Therefore, it is necessary to carry out further and systematic research on the interaction mechanism between polymer tanning agents and collagen, which is a very important environmental pressure. Chromium contamination is one of the three major sources of tanning. Conventional chromium tanning has only about 70% of the chromium salts in the skin. Absorption, and the rest go to the waste liquid to form pollution to the environment - if necessary, it is imperative.

Jin Yong et al.: Advances in the research on the interaction between polymer tanning agents and collagen