Nanomechanical systems that are designed to trap and release molecules from pores in response to a stimulus are currently the subject of intense investigation.[1–23] Such systems have potential applications for precise drug delivery. A photo-activated material, for example, could release a drug under external control at a specific time and location for phototherapy. Nanomaterials suitable for this type of operation must consist of both an appropriate container and a photoactivated moving component.

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Light‐Activated Nanoimpeller‐Controlled Drug Release in Cancer Cells

Construction of a pH-Driven Supramolecular Nanovalve

In agricultural field, polymers are widely used for many applications. Although they were used, in the first time, just as structural materials (inhert polymers), in the last decades functionalized polymers revolutionized the agricultural and food industry with new tools for several applications. Smart polymeric materials and smart delivery systems helped the agricultural industry	to combat viruses and other crop pathogens, functionalized polymers were used to increase the efficiency of pesticides and herbicides, allowing lower doses to be used and to indirectly protect the environment through filters or catalysts to reduce pollution and clean-up existing pollutants. This report will review the key aspects of used polymers in agricultural area, highlighting current research in this field and the future impacts they may have.

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Polymer in Agriculture: a Review

Advances in controlled release pesticide formulations: Prospects to safer integrated pest management and sustainable agriculture.

About 3.5 billion ha of land, which amounts to almost 30% of the total solid land of the world, has been degraded by human activities. The ecological restoration of these lands is a major challenge for mankind since they are the only option left for increasing the amount of arable land and producing food for the ever growing worldwide population. One common feature of these degraded lands is the fact that their organic soil matter is degraded also. Rainfall therefore, changes from a blessing to a menace since it is not kept in the soil and therefore causes erosion. A solution for the restoration of these lands could be the application of superabsorbent polymers (SAPs) to these soils. These substances are like ‘artificial humus’ as they are hydrophilic and contain carboxylic groups. This enables them to bind cations and water. They have the following advantages for the restoration of degraded lands. They increase the plant available water in the soil which enables the plants to survive longer under water stress. SAP amendment to soils reduces the evapotranspiration rate of the plants. They induce a significantly higher growth rate in plants growing on SAP amended soil. They bind heavy metals and mitigate their action on plants. They mitigate the effects of salinity. The benefits of SAP amendment to soils substantially outweigh their costs.

Application of Superabsorbent Polymers for Improving the Ecological Chemistry of Degraded or Polluted Lands

Acrylic-based copolymers of methyl methacrylate (MMA) and methacrylic acid (MAA) have been prepared by solution and bulk polymerization techniques using benzoyl peroxide (BPO) as an initiator. Three polymers were prepared with a varying ratio of MMA/MAA. In an effort to increase the hydrophilicity of the matrix, one MMA/MAA polymer was prepared by adding an additional amount of 2-hydroxy ethyl methacrylate (HEMA). All the polymers were crosslinked in situ by ethylene glycol dimethacrylate (EGDMA). These polymers were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. Viscous flow characteristics were determined from solution viscosity and rheological measurements. Dynamic and equilibrium swelling experiments were carried out under varying pH conditions (i.e., 0.1N NaOH, 0.1N HCl, and double-distilled water). Partially crosslinked hydrogels show varying hydrophilicity because of the presence of carboxylic acid groups making them pH-responsive. Swelling increased with an increasing number of —COOH groups on the polymer backbone and the hydrophilicity varied with changing pH. Cypermethrin, a widely used pesticide, and cupric sulfate, a model micronutrient, were loaded into these pH-sensitive hydrogels to investigate their controlled release characteristics. The in vitro release rates of both compounds have been carried out under static dissolution conditions at 30°C. Release data have been fitted to an empirical relation to estimate transport parameters. The release results have been discussed in terms of the varying hydrophilicity of the hydrogel network polymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 394–403, 2003

Timothy Chipuk

Papers

pH-sensitive acrylic-based copolymeric hydrogels for the controlled release of a pesticide and a micronutrient