pH-Responsive Controlled-Release Fertilizer with Water Retention via Atom Transfer Radical Polymerization of Acrylic Acid on Mussel-Inspired Initiator

Abstract

This work reports a polydopamine-graft-poly(acrylic acid) (Pdop-g-PAA)-coated controlled-release multi-element compound fertilizer with water-retention function by a combination of mussel-inspired chemistry and surface-initiated atom transfer radical polymerization (SI-ATRP) techniques for the first time. The morphology and composition of the products were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), gel permeation chromatography (GPC), and inductively coupled plasma (ICP) emission spectrometry. The results revealed that the stimuli-responsive layer formed by a Pdop inner layer and a PAA outer corona exhibit outstanding selective permeability to charged nutrients and the release rate of encapsulated elements can be tailored by the pH values. At low pH, the Pdop-g-PAA layer can reduce nutrient loss, and at high pH, the coating restrains transportation of negative nutrients but favors the release of cations. Moreover, PAA brushes provide good water-retention property. This Pdop-graft-polymer brushes coating will be effective and promising in the research and development of multi-functional controlled-release fertilizer.

Cellulose-based graft copolymers prepared by simplified electrochemically mediated ATRP

“…It is expected that these synthesized graft copolymers have great potential in biomedical, such as tissue engineering scaffolds with double-responsive and antifouling properties. Linear form of PAA has been one of the most extensively studied industrially important watersoluble polymer [16]. It has significant pH response, which is mainly due to high concentrations of -COOH groups [17,18], and therefore it is widely used as pH-sensitive drug delivery systems [19][20][21].…”

Organic acid coated-slow-release phosphorus fertilizers improve P availability and maize growth in a tropical soil

“…Among these slow-release fertilizers (SRF), the major categories are fertilizers coated with different materials. Recently, a number of materials have been tested: biodegradable polymers (Wu and Liu, 2008;Ao et al, 2013;Jia et al, 2013;Lubkowski et al, 2015), superabsorbent polymers (Liang et al, 2007;Teodorescu et al, 2009), commercial polymers (Figueiredo et al, 2012;Silva et al, 2012;Ma et al, 2013), oxides (Zhang et al, 2014) and fly ash (Dong et al, 2016). More specifically for MAP, a previous study has shown that when P is more slowly released from a thin polymer coated-MAP fertilizer granule, it increased P availability, P uptake and P use efficiency by barley plants (Pauly et al, 2002).…”

Characterization of p(AA‐co‐AM)/bent/urea and its swelling and slow release behavior in a simulative soil environment

“…The release rates for both samples were always higher in basic solution than in acidic or neutral solutions. These results were attributed to the deprotonation of the carboxylic groups in the basic solution, and the strong electrostatic repulsion between the carboxylic groups also make the network expand, which is convenient for the nutrients to pass through the network . In contrast, the protonation of carboxylic groups at a low pH level prevented the efficient anion–anion electrostatic repulsion, and subsequently causes a shrinkage of the network, which is unfavorable for the transportation of nutrients .…”