A Brief Overview of (AB)n Block Copolymers
Block copolymers tend to combine properties of their constituent blocks; This property is the second of a polymer. causes it to be modified by the component. Properties of block copolymers similar in characteristics; however, the presence of chemical bonds between the blocks ensures their stability. Due to their chemical composition and molecular structure, block copolymers have many application areas. These are used in many fields such as Textile, Coating Material, Personal Care Products in Cosmetics, Agricultural Chemicals.
It also gains different properties according to the groups attached to this polymer. It can be used for low or high heat resistance, antifoam, wetting, lubricant effect, additive material, increasing permanence, surface active purpose, softness, antistatic feature, hydrophilicity.
The Use and Effects of (AB)n Block Copolymers in Textiles
In the case of amine bonding to linear polysiloxanes, which basically have hydrophobic (water-repellent) properties, chain strength increases and an improvement in softness is observed. Amino functional silicone polymers have a high fiber affinity and a very smooth placement on the fiber. Elasticity and softness increase in the applied textile product.
The reactivity of these modified silicones is increased by the amount and type of amino groups incorporated into them. The larger the group, the softer and more beautiful the attitude will be. The biggest disadvantage of amino-functional silicone softeners is their low yellowing resistance. This is due to the fact that amino groups are vulnerable to atmospheric oxygen and undergo oxidation. According to Gokulnathan S. and Thomas PT, oxygen causes oxidation in amino (-NH2) groups under the influence of light (photo-oxidation) or temperature (term oxidation), resulting in the formation of nitro (-NO2) groups, and nitro groups in short wavelengths of light in the visible region. It causes the formation of azo groups, which are strong brown and yellow chromophores that perform adsorption. Other important disadvantages are; As the number of amino groups increases, their sensitivity to temperature, alkalinity, high shear forces, and external factors such as electrolytes increases. The positive effect of amine bonds is the increase in water solubility, which means that the amount of surfactant needed in the emulsion system causes it to fall.
In the structures obtained by the quaternization of polysiloxane structures, the increase in the angle between the bonds will create a volume and elastomeric effect, thus providing a fuller and voluminous feel, making the product even more hydrophilic, causing an increase in the moisture capacity after application to the fabric. The increase in the hydrophilic part (EO) of the molecule can also enable the product to disperse easily in water, which leads to significant improvements in the stability strength of conventional amino silicones. Unlike amino functional or polyether structures of (AB)n polymers, which consist of repeated blocks, the strong polar amine structure reduces the friction coefficient between the fibers thanks to its interaction with the textile surface, which increases the surface lubricity of the fabric.
The hydrides of the amines in the block structure prevent yellowing that may occur due to temperature. It provides. At the same time, it reduces the color change problem in dark colors. Since the polyether structures in the chain will accelerate the penetration into the textile, they positively affect the washing resistance and hydrophilicity. In emulsion types with different particle sizes that can be developed thanks to the high force in the chain, it significantly increases the stability and strength in general. Therefore, textiles treated with silicone block copolymer have a similar feel to conventional hydrophobic silicones, but they do not adversely affect the hydrophilicity of the textile.
Working Principle of (AB)n Block Copolymers on Fabric
Since aminosilicones have cationic amino (-NH2) groups, they are easily taken up by anionic surfaces. The cationic groups are oriented with a perfect orientation towards the fiber surface, while non-polar
groups are located outward from the fiber surface. For this reason, cotton containing an amorphous structure They give effective results on fabrics. However, synthetic fabrics such as polyester and polyamide are free from negative charges.
Since we cannot talk about it, the same effect cannot be obtained. (AB)n block copolymers have linear structure and nonionicthey form a film by covering the surface thanks to the character. They move along the surface without disturbing the network structure they form on the surface and show a perfect spread. In this way, a very good surface and inner softness, surface lubricity, and in addition to these, an anti-crease effect can be provided.
Charma® Hill is a hydrophilic silicone polymer produced with (AB)n block copolymer technology. Thanks to the production of this technology, it can be easily dissolved in water without the need for an emulsifier, and thus it can be diluted at the desired rate.
The most important advantage is that it does not cause a decrease in wet / dry sublimation fastness caused by emulsifiers. Its ionic structure is nonionic. Thanks to its nonionic character, it allows combination with softener systems with different ionic structures. Thanks to the coating effect in synthetic fabric types, it reduces the surface friction coefficient and provides an excellent touch. This is the main result of its homogeneous movement on the fabric surface compared to amino silicones. It is suitable for impregnation and extraction processes. It can be used in various fabric types such as synthetic (polyester, polyamide) and blended fabrics (cotton/pes, cotton/lycra).
Advantages of New Generation Silicones;
- High stability in harsh conditions (optical, electrolyte, pH - temperature resistance, shear strength)
- It can be easily dissolved with water,
- Does not cause color change,
- Does not cause yellowing
- Can be repainted,
- An effective touch is achieved even with low usage;
- It gives hydrophilic property,
- It does not take back the fastnesses,
- A silky touch is obtained.