塑料浮选体系中的表面重构及其调控机制研究

Surface reconstruction in polymer surface is a spontaneous behavior in response to the changes of temperature and environment, which possesses significant effects on the flotation behavior of plastics with respect to time and space. In order to systematically ascertain surface reconstruction of polymer macromolecule, plasticizer molecule and migrated additives in plastics flotation, with the aid of modern equipment of surface analysis, the complex and regular reconstruction driven by minimal interface energy in plastic surface will be investigated at the molecular level from thermodynamics and kinetics. Furthermore, the effects of external environmental factors will be studied, including interface patterns in each stage of flotation, external fields (plasma, microwave and UV), ambient temperature, oxidation and wetting agents adsorption, on metastable and steady state of surface reconstruction. The expected difference in the floatability of different plastics will be obtained and enhanced by regulating and controlling the turnover, oxidation or degradation process of the hydrophilic and hydrophobic molecular chains of polymers, non-polar and polar molecule groups of plasticizer. Consequently, an efficient regulating mechanism concerning surface reconstruction and plastics flotation will be accomplished to facilitate separation of waste plastics in complex systems.

表面重构是高分子材料表面为响应温度和环境变化的自发行为，其具有时间和空间效应的重构模式对塑料的浮选行为产生了重要影响。本项目将借助近现代表面分析仪器与检测手段，对塑料浮选体系中的聚合物大分子表面重构、增塑剂小分子的迁移与表面重构、填充剂外露后表面重构三大类表面重构行为进行系统研究，从热力学和动力学两方面在分子（基团）层面上描绘出塑料表面在界面能最低原则驱动下的复杂而有序的重构情景。在此基础上，通过合理改变塑料浮选各阶段的相界面接触形式、外场（等离子体、微波、UV辐照）作用方式、环境温度、氧化体系、润湿剂吸附模式等外部环境，创造和利用稳态甚至亚稳态状况下的表面重构结果，调节和控制聚合物疏水链段、亲水链段、增塑剂分子非极性基团、极性基团的翻转、氧化或降解进程，逐步积累和放大塑料之间的可浮性差异，从而确立表面重构基础上的塑料浮选高效调控机制，为实现复杂体系废旧塑料的浮选分离创造条件。

表面重构是高分子材料表面为响应温度和环境变化的自发行为，其具有时间和空间效应的重构模式对塑料的浮选行为产生了重要影响。本项目借助近现代表面分析仪器与检测手段，从热力学和动力学两方面在分子（基团）层面上深入研究了塑料浮选体系中在次氯酸盐、过硫酸盐、高铁酸盐、二氧化氯、Fe2+/过硫酸钠、Fe3+/亚硫酸钠、H2O2/Fe2+、乙二醇/KOH、丙三醇/尿素、Fe3O4纳米颗粒、碳酸钙悬浮液等作用下ABS、PC、PMMA、PET、PS和PVC等塑料的表面重构、表面氧化、表面吸附和表面罩盖等行为，成功揭示了环境诱导、表面水解、氨解、醇解、自由基攻击、自催化降解、含氧基团引入、非均相催化氧化、分子间酯交换、表面烷氧基化、基团翻转、纳米颗粒涂层等在高分子聚合物表面发生的一系列亲/疏水化调控作用，建立了在塑料表面活性位点、表面反应和表面重构规律基础之上的塑料浮选“基因编辑”技术，成功实现了多种废旧塑料的高效浮选分离，同时为环境中微塑料的最终处置提出了新的思路。