Crystallization Features of Normal Alkanes in Confined Geometry

• DOI: 10.1021/ar400116c
• Publication Date: 2013-08-15T15:50:56Z
• Authors: Yunlan Su; Guoming Liu; Baoquan Xie; Dongsheng Fu; Dujin Wang
• Keywords: Miscibility; Metastability

How polymers crystallize can greatly affect their thermal and mechanical properties, which influence the practical applications of these materials. Polymeric materials, such as block copolymers, graft polymers, polymer blends, have complex molecular structures. Due to multiple hierarchical structures different size domains in systems, confined hard environments for crystallization exist widely The geometry is closely related both phase metastability lifetime polymer. This affects miscibility, microphase separation, behaviors determines performance materials how easily be processed. Furthermore, effect metastable states needs clarified polymers. However, scientists find it difficult propose a quantitative formula describe transition dynamics systems. Normal alkanes [CnH2n+2, n-alkanes], especially linear saturated hydrocarbons, provide well-defined model system studying surfactants, lipids. Therefore, deeper investigation normal alkane behavior confinement will help understand crystalline ultimate properties many polymeric polyolefins. In this Account, we an in-depth look at research concerning n-alkanes binary mixtures microcapsules by our laboratory others. Since 2006, group has developed technique synthesizing nearly monodispersed n-alkane containing with controllable surface porous morphology. We applied situ polymerization method, using melamine-formaldehyde resin shell material nonionic surfactants emulsifiers. solid stable three-dimensional (3-D) confining environment. studied parameters microencapsulated n-alkanes, including freezing, rotator phase, separation differential scanning calorimetry (DSC), temperature-dependent X-ray diffraction (XRD), variable-temperature solid-state nuclear magnetic resonance (NMR). Our investigations revealed new direct evidence existence freezing n-alkanes. By examining differences among chain packing nucleation kinetics between bulk solutions counterparts, also discovered mechanism responsible formation phase. addition, found that suppresses lamellar ordering longitudinal diffusion, play important role stabilizing solution microcapsules. work provided insights into other mixed system, waxes, lipids, blends geometry. These works profound understanding relationship structure context therefore advance ability improve incorporating