Development of Fertilizer Coatings from Polyglyoxylate–Polyester Blends Responsive to Root-Driven pH Change

Abstract

Many current controlled-release fertilizers (CRFs) are coated with nonbiodegradable polymers that can contribute to microplastic pollution. Here, coatings of self-immolative poly­(ethyl glyoxylate) (PEtG) capped with a carbamate and blended with polycaprolactone (PCL) or poly­(l-lactic acid) (PLA) were evaluated. They were designed to depolymerize and release fertilizers in the vicinity of plant roots, where the pH is lower than that in the surrounding environment. PEtG/PCL coatings exhibited significant temperature and pH effects, requiring 18 days at pH 5 and 30 °C, compared to 77 days at pH 7 and 22 °C, to reach 15% mass loss. Plant roots were also effective in triggering coating degradation. Spray-coating and melt-coating were explored, with the latter being more effective in providing pellets that retained urea prior to polymer degradation. Finally, PEtG/PCL-coated pellets promoted plant growth to a similar degree or better than currently available CRFs.

Authentication of Microplastic Accumulation in Customary Fruits and Vegetables

“…Primary MPs are released directly into the environment, whereas secondary MPs are formed by the breakdown of large-size chunks. Microplastics can enter agroecosystems through a variety of routes, including fertiliser coatings (Heuchan et al, 2019), wastewater irrigation (Zhang and Liu, 2018), compost addition and biosolids application (Nizzetto et al, 2016;Weithmann et al, 2018), and, most importantly, the use of mulching lm (Nizzetto et al, 2016). (Liu et al, 2014;Qi et al, 2018).…”

Microplastics interaction with terrestrial plants and their impacts on agriculture

“…This is mainly attributed to the application of biosolids from recycled organic wastes (Corradini et al., 2019), irrigation with waste‐treated water (Gündoğdu et al., 2018), and plastics mulching (Astner et al., 2019; Duis & Coors, 2016; Horton et al., 2017; Lv et al., 2019). Biosolids and treated wastewater are applied as fertilizer and for irrigation purposes, respectively (Allen et al., 2019; Mohapatra et al., 2016; Nizzetto et al., 2016), thus increasing MPs flux in agroecosystems (Huechan et al., 2019). In agricultural soils, the most abundant MP polymers are PS, PE, and polypropylene (Piehl et al., 2018).…”

Post-polymerization ‘click’ end-capping of polyglyoxylate self-immolative polymers

“…2 Additionally, a wide range of trigger endcaps have been reported to date, allowing SIPs to degrade in response to various environmental, chemical, and biological stimuli. 3 These unique properties of SIPs have fueled interest for their use in controlled release systems, [4][5][6][7][8][9][10] stimuli-respon-sive coatings, 11,12 chemical sensors, [13][14][15] and degradable bulk materials. [16][17][18] Since their debut in 2008, 19 a handful of SIP designs have been reported with degradation mechanisms based on 1,4and 1,6-elimination reactions of aromatic compounds, [20][21][22] heterocyclization reactions, 23,24 olefin sulfone elimination reactions, [25][26][27] and the depolymerization of polyacetals.…”