Binary blend polymer films

As nuclear reactions are isotope specific, NRA may be used, for example, to distinguish the distribution of binary blends of polymers in a polymer film, where one of the polymers is labelled with deuterium. The depth distribution of the deuterium atoms can be established and hence that of the labelled polymers. 

In a large part of what we have discussed above, we considered binary polymer mixtures. However, the situation is somewhat different, if instead of polymer blends, thin films of block copolymers are investigated. Due to the molecular connectivity of the different blocks, the inherent length scale is now determined by the size of the molecules. Early experiments focussed on the thin film morphology in symmetric diblock copolymers, where surface interactions tend to orient the block copolymer lamellae parallel to the boundary surfaces. In contrast to most bulk specimens, the planar interfaces lead to the formation... 

Fig. 2.6 Extinction spectra of binary blend and pure polymer films. All films were spun from chloroform and are 170nm thick. At the time this measurement was done, the films containing F8 were significantly scratched, which explains the large scattering background seen in...

The films of pure P(BA-co-BT), pure PEO, binary blends P(BA-co-BT)/TDP(92/8 wt%/wt%) and PEO/TDP (92/8 wt%/wt%), and the ternary blend of P(BA-co-BT)/PEO/TDP containing a constant composition(8wt%) of TDP with various P(BA-co-BT)/PEO ratios were prepared by conventional solution casting method. 5wt% Polymer solution in 1,4-dioxane was stirred for 6-8 h and cast on a Teflon dish. The solvent was allowed to evaporate slowly for 1 day at ambient temperature. The resulted films were then dried in a vacuum oven at 50 °C for 2 days to remove residual solvent and subsequently compression molded between Teflon sheets for 3 min at 160 °C under pressure of 5MPa by using laboratory press (Mini Test Press-10, Toyoseiki Co., Japan). 

The lack of the bipolar transport in binary blends of polymers for most of the compositions shows that controlling the thin-film morphology is challenging. Therefore, the key issue is to realize an interpenetrating and bicontinuous networks of binary polymer blends in order to establish ambipolar charge transport. 

Bar sky and Robbins performed NEMD simulations of the interfacial structiue and rheology of binary blends of symmetric polymers which were made immiscible to various degrees by adjusting the cross-interaction parameters. A liquid film was sheared by sliding boundaries. They found that there was a difference in velocity of the two species at the interface, suggesting a partial slip boundary condition. They attributed this to a difference in the positions of the centres of mass of the species on opposite sides of the interface. The viscosity in the interfacial region was lower than the bulk viscosity. 

Friend et al. [31] reported the use of inkjet printing (IJP) to produce thin polymer films with a controlled phase separation of binary polymer blends. Photovoltaic devices comprising a blend of poly(9,9- dioctylfluorene-co-bis-N,N -(4-butylphenyl)-bis-N,N -phenyl-l,4-phenylenediamine) (PFB) with F8BT and LEDs using a blend of F8BT with poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenyl-amine) (TFB) were fabricated (Figure 25.9). 

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