氧化石墨烯插层聚β-羟基丁酸酯复合材料的结晶形态与宏观性能

由微生物直接合成的聚β-羟基丁酸酯（PHB）可实现从原料合成到加工成型和回收降解的全周期生态循环, 在生物医用和包装材料等领域有着重要的应用前景. 受制于PHB自身成核能力差导致的球晶尺寸偏大等不利结晶形态特点, 其制品存在抗冲韧性差、 延展率低和易蠕变等缺陷. 本文提出了水相加工和受限成型相结合的制备方法, 将氧化石墨烯（GO）纳米片在水溶液中充分剥离后, 直接包覆于亚微米级PHB微颗粒表面形成PHB@GO复合物, 然后在压力场下受限成型获得GO插层PHB纳米复合材料. 研究结果表明, 即使在极低GO添加量（质量分数0.1%）下, PHB的等温和非等温结晶能力都有显著提高, 并获得晶核密度高且晶体尺寸均一的结晶形态. 插层GO纳米片还促使复合材料发生了脆-韧转变, 使其拉伸强度和延展性均成倍提高, 同时显著增强了动态热力学性能、 抗蠕变性能和热学性能.

Self-Assembly of Graphene Oxide at Poly(3-hydroxybutyrate) Microparticles Toward High-performance Intercalated Nanocomposites

As one of the most important natural biopolymers， poly（3-hydroxybutyrate）（PHB） has been identified by an ecofriendly lifecycle from bacterial synthesis to practical processing and recycling， holding great promise in applications for biomedical and packaging materials. However， due to the intrinsic characters including poor self- nucleation capability and excessively large spherulites， the application of PHB is dwarfed by low impact resistance， poor ductility and high creep compliance. Herein， a combination of aqueous processing and confined structuring was proposed to prepare graphene oxide（GO）-intercalated PHB nanocomposites. In specific， GO nanosheets were exfo- liated and dispersed in water， which would encapsulate the submicron PHB microspheres to form the PHB@GO self-assemblies， followed by confined structuring under a high pressure above the melting temperature of PHB. Albeit at an ultralow loading of 0.1%（mass fraction）， the intercalated GO nanosheets showed high capability to enhanced the isothermal and non-isothermal crystallization kinetics of PHB， resulting in highly dense spherulites with a relatively uniform size. An unexcepted brittle-ductile transition was developed in the intercalated nanocomposites， leading to remarkable increase in tensile strength and elongation at break. This was accompanied by significant rise of thermomechanical properties and creep resistance， especially at high temperatures. The flexibility in the choice of functional nanofillers permits broad applications in the fabrication of high-performance PHB-based composites.