The maturation of biobased polymer synthesis process has led to the rapid adoption of biobased controlled-release fertilizers (BCRFs). Despite this progress, the loose structure, low cross-linking density, and poor water repellency of current biobased coatings result in short controlled-release periods, which do not meet the long-term nutrient demands of crops throughout their reproductive phases. Moreover, existing modifications to address these issues often involve the addition of external additives, which can increase biotoxicity and cost. In this study, castor oil-based hyperbranched polyol (COHBPs) was synthesized from castor oil (CO) using a “one-pot method.” We report the development of high cross-linking density biobased hyperbranched polyurethane (COHBPPFs) as a coating for BCRFs. Gel content and SEM analysis demonstrated that COHBPPFs exhibited a high degree of cross-linking. Mechanical testing using an electronic universal testing machine, along with AFM results, highlighted the superior mechanical properties of COHBPPFs compared to traditional coatings. COHBPPFs significantly enhanced controlled release performance, with a 3% coating content providing nearly 50 days of controlled release, a marked improvement over conventional coatings. The controlled release mechanism of COHBPPFs was elucidated by modeling the cross-linking process of COHBPs with PAPI. This study offers a comprehensive examination of CRF coatings from multiple perspectives and provides valuable insights into the development of high cross-link density, environmentally friendly, and renewable biobased CRFs.

中文翻译：

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通过高交联密度超支化生物基聚氨酯涂料提高控释肥料的寿命和机制


生物基聚合物合成工艺的成熟导致了生物基控释肥料 （BCRF） 的快速采用。尽管取得了这些进展，但当前生物基涂料的松散结构、低交联密度和较差的防水性导致控释期短，无法满足作物在整个生殖阶段的长期营养需求。此外，为解决这些问题而进行的现有修改通常涉及添加外部添加剂，这会增加生物毒性和成本。在这项研究中，使用“一锅法”从蓖麻油 （CO） 合成了蓖麻油基超支化多元醇 （COHBP）。我们报道了高交联密度生物基超支化聚氨酯 （COHBPPFs） 作为 BCRFs 涂层的开发。凝胶含量和 SEM 分析表明 COHBPPFs 表现出高度的交联。使用电子万能试验机进行的机械测试以及 AFM 结果突出了 COHBPPF 与传统涂层相比的卓越机械性能。COHBPPF 显著提高了控释性能，3% 的包衣含量可提供近 50 天的控释，比传统包衣有了显着改进。通过模拟 COHBPs 与 PAPI 的交联过程来阐明 COHBPFs 的控释机制。本研究从多个角度对 CRF 涂层进行了全面检查，并为高交联密度、环保和可再生生物基 CRF 的开发提供了有价值的见解。