The research and experimental-design studies carried out in the Institute of Physical Organic Chemistry NAS of Belarus in the area of the chemical and structural modification of the industrial polymers are discussed. The main studied of the functional polymers are focused mainly on:  new materials based on fibrous ion-exchangers for environmental applications (ion exchangers, catalysts and chelate type sorbents) for water and air purification in microelectronics, power industry and agriculture;  technology for the production of new types of semipermeable membranes and membrane equipment for separation in liquid and gas media;  fundamentals of the design of new polymer composite materials and functional materials for industry, agriculture and environmental applications. Fibrous ion-exchangers and catalytic materials The line of chemically modified fibers (trademark Fiban®) has been developed including all types of ion exchangers (high and low basic, high and low acidic, chelating and catalytically active). The advantages of them are:  high rate of ion exchange and sorption processes;  high flux;  capability of the application of thin filter layers (2-6 cm);  high chemical resistance and the capability for multiple regeneration. Due to these advantages the fibrous ion-exchangers have the broad area of practical application: purification of gaseous toxic waste emissions in industry and agriculture, ultrafine air purification for electronic industry, personal protective equipment of the human skin and respiratory organs from toxic substances, drinking water purification from natural organic matter, heavy metal ions, arsenic, nitrates and etc., catalytic deoxygenation of feed water in power industry. In the area of membrane technology, the new methods of the fabrication of microfiltration membranes on the reinforcing substrate, ultrafiltration membranes from polyacrilonitrile, polysulfone, polyethersulfone for concentration and purification of enzymes, fractionation of biological media, hollow fiber membranes for water pretreatment for power plants in energy saving dead-end filtration mode have been developed. Functional polymers for agriculture The fundamentals of the preparation and properties of the micro fertilizers based on the nanoparticles of the microelements (iron, copper, cobalt, selenium and etc.) stabilized by the modified polysaccharides are discussed. It was shown that high efficiency can be achieved using 100 times less amount of micro fertilizers compared to salt and chelates. The slowly dissolving shell from biogenic polymer of the nanoparticles prevents the burst release of microelements and provides the prolonged effect and reduces toxicity.