Hydrophilic Polymers

Hydrophilic polymer refers to organic polymers rich in polar groups, including natural polymers such as starch, protein, cellulose, and the synthesis of polyacrylic acid, polypropylene phthalimide, polyvinyl alcohol, polyurethane, polyphthalamine polymer. After more than half a century of development, hydrophilic polymers have become a relatively mature research field. Hydrophilic polymers have good biocompatibility and are widely used in agricultural, forestry, sanitary products, medical care, modified thickening and other conventional applications. Due to the diversity and intelligence of hydrophilic polymers, in recent years, researchers have conducted exploratory experiments in emerging industries such as tissue engineering, biological materials, drug release, and optoelectronic information materials, and have obtained a large number of research results, which have huge potential application value.

Figure 1. Trimethylamine oxynitride (TMAO) super hydrophilic bionic polymer

Applications:

• Thickener: Cross-linked polyacrylic acid can be used as a thickener as a typical hydrophilic cross-linked polymer. Later, as various polymerization methods emerged endlessly, the application fields of hydrophilic cross-polymers became wider. Thickeners synthesized by inverse suspension polymerization, emulsion and inverse emulsion polymerization are widely used in the petrochemical industry, printing and dyeing industries. Among them, the polyacrylic acid synthesized by the precipitation polymerization method has been rapidly developed and used in the modification and thickening of liquid drugs and cosmetics.
• Water retention in agriculture and forestry: Some researchers grafted starch with acrylonitrile to produce water-absorbing polymers with a water absorption capacity far exceeding that of traditional materials. They are mainly used to maintain soil moisture in arid areas. When the water-absorbing resin is mixed into the soil, it can significantly increase the water content of the soil, reduce the number of watering times, and improve the agglomerate structure of the arid soil, increase crop yield and seedling survival rate.
• Medical and health care: Due to the characteristics of non-toxic, non-irritating to the human body, no side reactions, and no blood coagulation, the super absorbent resin has been widely used in the field of medicine and health in recent years. The main products are baby diapers, sanitary napkins, medical blood-sucking sponges, etc.
• Chemical industry: Quaternary ammonium salt is a common type of cationic high hydrophilic polymer, which is mainly obtained by direct polymerization of dimethyl diallyl ammonium chloride, methacryloxyethyl dimethyl ammonium chloride and other monomers. It is mainly used in textile, papermaking, petrochemical, cosmetics, water treatment, environmental treatment, corrosion science and material surface modification and other fields. For example, some researchers used ammonium persulfate as an initiator and modified the hydroxyl group of polyvinyl alcohol with dimethylamino ethyl methacrylate or 4-vinyl pyridine. The modified products can be used in inkjet printing medium coating, which greatly improves the water-resistance of the image.

Figure 2. Quaternary ammonium salts hydrophilic polymer

• Construction: Polymers synthesized with acrylamide as the main monomer have good water solubility, high reaction activity and low toxicity, and are widely used in the fields of drug release, bioengineering, high-efficiency catalysis and composite materials. In particular, there are many applications in construction, such as improving the water content of concrete, repairing and plugging cracks in buildings, adhesives, grouting materials and so on.

Figure 3. Polyacrylamide

References:

1. Sang G L, Kang J B, Kim S R, et al(2016). "Enhanced topical delivery of tacrolimus field a carbomer hydrogel formulation with transcutol." Drug Development and Industrial Pharmacy. 42(10):1636-1642.
2. Xue Tiezhong, Hua Man, Yuan Lixin.(2009) "Application of Carbo Resin in Cosmetics." Daily Chemical Science. 32(11):39-42.