Blown films with balanced in-plane properties from polypropylene-clay nanocomposites though silane coupling

Layered silicates present interaction sites at both faces and edges of the nanolayers and silane coupling agents that locate at both sites lead to polymer nanocomposites with superior melt strength and properties. This work’s objective was (a) to investigate the effectiveness of solvent-free, vapor phase, silane treatment of the nanolayers for formulating masterbatches and (b) to compare the mechanical properties of 1 mil thick blown films from polypropylene copolymer nanocomposites with such coupling, to films from the neat polypropylene. The nanocomposite blown film tensile modulus and tensile strength improved along both the draw direction and the transverse direction. In addition, their elongation to failure was close to 500% along both directions, in contrast to values of 500% along MD and 170% along TD for the neat PP copolymer. These trends may be understood in terms of the crystalline lamellar orientation distribution in the films. FESEM images revealed that cross-hatched lamellae were absent from the unfilled PP blown film and were pervasive in the nanocomposite blown film. The nanolayers were oriented in the film plane with the longer dimension largely along the MD. The lower extent of lamellar orientation around nanolayers may be attributed to the strong reduction in the polymer chain mobility attached to the nanolayers.

Lamellar Orientation of a Block Copolymer via an Electron-Beam Induced Polarity Switch in a Nitrophenyl Self-Assembled Monolayer or Si Etching Treatments

Directed self-assembly (DSA) was investigated on self-assembled monolayers (SAMs) chemically modified by electron beam (EB) irradiation, which is composed of 6-(4-nitrophenoxy) hexane-1-thiol (NPHT). Irradiating a NPHT by EB could successfully induce the orientation and selective patterning of block copolymer domains. We clarified that spatially-selective lamellar orientations of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) could be achieved by a change of an underlying SAM. The change of an underlying SAM is composed of the transition of an NO2 group to an NH2 group, which is induced by EB. The modification in the polarity of different regions of the SAM with EB lithography controlled the lamellar orientation of PS-b-PMMA. The reduction of the NPHT SAM plays an important role in the orientation of block copolymer. This method might significantly simplify block copolymer DSA processes when it is compared to the conventional DSA process. By investigating the lamellae orientation with EB, it is clarified that only suitable annealing temperatures and irradiation doses lead to the vertical orientation. We also fabricated pre-patterned Si substrates by EB lithographic patterning and reactive ion etching (RIE). DSA onto such pre-patterned Si substrates was proven to be successful for subdivision of the lithographic patterns into line and space patterns.