Solution cast from toluene samples

Sample Preparation. Samples for mechanical studies were made by compression molding the polymers at 150°C between Teflon sheets for 15 minutes followed by rapid quenching to room temperature in air. These will be referred to as PQ (press-quenched or simply quenched) samples. The thickness of the PQ samples was around 10 mils (0.25 mm). The thermal history of all of the PQ samples (HBIB, HIBI, and LDPE) were essentially the same. They were used within one week after they were pressed. Samples for morphology, SALS and SEM studies were prepared from toluene solutions. These films were cast on a Teflon sheet at 80 C from a 1% (by weight) solution in toluene. These films were about 5 mils in thickness. When the polymer films had solidified (after 5 hrs), they were stored in a vacuum oven at 80°C for two days to remove residual solvent. These samples will be designated by TOL (solution cast from toluene). 

Samples of /the polymers for physical evaluation were prepared by film casting from toluene solution at 90°C. and allowing the crystallization to occur by cooling the melt. It was observed that phase separation occurred in the melt in the case of the H2-BIB but not for the H2-BBB. These materials could also be compression molded at 1<40°C., but optimum results appeared to be obtained with the film-cast samples. 

Thin films with a thickness of 50 pm of a commercially available PS-PB-PS triblock copolymer (e.g. from BASF, 74% PS, 26% PB) are prepared by solution casting from a 3% solution in toluene onto TEFLON -foil, which is placed in a precleaned petri-dish. The solvent is slowly evaporated over a period of 2 weeks. Residual solvent is then removed and films are annealed under reduced pressure in a vacuum oven at 120°C (48 h). Finally, the films are removed from the support and are uniaxially stretched at a constant strain rate of 0.1 s 1 beyond the yield point at room temperature. ARM investigations are carried out on prestretched samples that are mechanically clamped or fixated by double-sided sticky tape onto the AFM sample holder. 

Film spectra were taken using thin films of polymer spun-cast on 1.6 mm thick fused silica flats, 25 x 25 mm square. All film samples were cast from xylene which had been previously dried over i)A molecular sieves. For the solution spectra, toluene was used after distillation from NaK alloy under Ar. The alkane solvents were obtained from a variety of sources and used without further purification. 

When neat 18a is heated in an evacuated sealed tube at 130°C for 1 hour 19a is obtained quantitatively. The polymer 19a is soluble in THF and the sample purified from THF-hexane is a yellow fibrous material with A/vv = 5.2 X 10 and A/n = 3.4 x 10, and readily forms amber, free-standing films by casting from toluene solution. By this ROP method, symmetrically and unsymmetrically substituted poly(ferrocenylsi-poly(ferrocenylsilanes) (19) [71,72] and polysilane-poly(ferrocenylsilane) copolymers, (20) [73] have been prepared. The ROP of [l]ferrocenophane with unsymmetrically methylated cyclopentadienyl rings (21) to investigate the C—Si bond cleavage mechanism in the thermal ROP gives a polymer (22) in which three types of silicon environment exist, showing that... 

This physically crosslinked matrix exhibits typical physical properties shown in Table 1. The data represent various neat S-B-S and S-I-S thermoplastic rubber samples cast from toluene solutions. 

A comparison of the dynamic mechanical properties of our HB at 35 Hz has been made to that of LDPE in Figures 14 A and B. The thermal and sample preparative history affects the mechanical properties of HB films to such an extent that in order to make a meaningful comparison one has to describe the exact history of the samples. Such a thermal history dependence has been examined for LDPE(54,57) and recently for HB.(12) Shown in Figures A and B are the mechanical spectra for HB-PQ, HB-Tol, and LDPE-PQ films. The compression molded films were prepared 1 to 2 days prior to the test. The solution cast film (from toluene), HB-Tol, was annealed at 80°C for 2-3 days and stored at room temperature for 1 week... 

The mechanical and rheo-optical properties of Kraton 101 have been studied by Stein136) using films cast from methylethyl ketone and from toluene solutions. The stress-strain curves, birefringence-strain curve, stress relaxation, birefringence relaxation, and dynamic mechanical spectra are dependent upon the morphology of the copolymer which in turn is dependent upon the conditions of preparations of the samples. 

The test specimens were prepared by casting from a 20% by weight solution in purified toluene at room temperature. Solvent evaporation in a controlled solvent atmosphere was carried out over a 24-hour period. The specimens were then vacuum dried for periods of time ranging from 36 hr (for 75°C) to seven days (for 40°C). This procedure yielded transparent, defect free, uniform thickness membranes with thicknesses between 0.012 and 0.018 in. Samples were prepared at the following final drying temperature TR-41-2443 at 55°C, TR-41-2444 at 55° and 75°C, and TR-41-2445 at 406 and 55°C. 

Polymer samples either isolated by precipitation with 2-propanol or permitted to stand in toluene solution rapidly became insoluble in toluene on standing in air. Brittle films cast directly from toluene solution were rapidly in-solubilized, unless antioxidants were present. 

Monodispersed polystyrene (PS) (Mw 3 k to 6.5 M Mw/MnAldrich Chemical Company Inc. and Polymer Source, Inc) was spin cast on to silicon (100) wafers from toluene solution. The solution concentration was varied to achieve thicknesses ranging from 20 to 350 nm, as determined by ellipsometry (Rudolph, AutoEL). The wafers were hydrogen passivated via HF etching prior to spin casting, and samples were annealed under vacuum (< 400 mtorr) for 4 hours at 165 to 170 °C prior to SPM experiments. 

In a typical test sample, two layers of polymer are placed in contact with one another to make a bilayer sample, or diffusion couple. If the polymers are different, then it may he possible to prepare a bilayer sample by sequential spin-casting with different solvents. For example, a diffusion couple of PMMA and PEO can be made by spin-casting PEO from methanol onto a PMMA film that was spin-cast from a toluene solution. For self-diffusion, or interdiffiision between similar polymers of different molecular weight, the second layer must normally be transferred from a separate substrate onto the first layer via floatation on high-purity water. 

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