Poly(imide‐siloxane) films with controlled thickness

Abstract

Polyimides containing siloxane moieties are used in some advanced applications. For example, these polymers can be employed as separation membranes in the form of self-standing, thin films. These products are formed by components of different polarities that have the tendency, at least partly, to separate in the final materials, with an impact on their final, bulk, and/or surface properties. The aim of this work is to study the dependence of the composition of the polyimide, poly(imide-siloxane) (PIS) and copolymeric PIS self-standing films differing in thickness on their properties. The important finding is that there is a rather large difference observed in the water contact angle on the film side oriented toward the air atmosphere during film preparation and that oriented toward a hydrophobic Teflon surface. Nevertheless, the gas transport properties of carbon dioxide and methane for these membranes are more influenced by the membrane composition than by the surface properties.

Optically active polyimides with different thermal histories of their preparation

“…Nevertheless, due to the lack of interactions between polymer chains, the thermal characteristics of that partly aromatic PI (the temperature corresponding to a 10% weight loss was 367 C in an air F I G U R E 1 Chemical structure of the polyimides based on 4,4 0 -(hexafluoro-isopropylidene)diphthalic anhydride and 1,2-diaminocyclohexane atmosphere and the temperature of glass transition was 225 C) are lower than those of a fully aromatic PI (e.g., for a PI based on 6FDA and 4,4 0 -oxydianiline, we determined for these parameters the values 504 C and 303 C, respectively). 18 The optical rotation of the PI based on 6FDA and (+)-DCH expressed as the specific rotation at 589 nm α ½ 20 589 was +128 deg cm 3 g À1 dm À1 (chloroform, c 1.168) and that of the PI based on 6FDA and (À)-DCH was À135 deg cm 3 g À1 dm À1 (chloroform, c 1.146). These values are higher than those obtained for the monomers (+)-DCH ( α ½ 20 589 = +39 deg cm 3 g À1 dm À1 ) and (À)-DCH ( α ½ 20 589 = À45 deg cm 3 g À1 dm À1 ) under similar conditions.…”

“…The curve shows no sudden decrease in the temperature range of 200–250°C, corresponding to the additional imidization occurring with the release of water. Nevertheless, due to the lack of interactions between polymer chains, the thermal characteristics of that partly aromatic PI (the temperature corresponding to a 10% weight loss was 367°C in an air atmosphere and the temperature of glass transition was 225°C) are lower than those of a fully aromatic PI (e.g., for a PI based on 6FDA and 4,4′‐oxydianiline, we determined for these parameters the values 504°C and 303°C, respectively) 18 …”

All-Polymer Piezo-Composites for Scalable Energy Harvesting and Sensing Devices

“…The PDMS reference sample, presented a water vapor sorption capacity of 0.62 wt% ( Figure 2 a), while the polyimide samples had the following maximum sorption values: PI1-4.58 wt%, PI2-2.24 wt%, and PI5-2.65 wt%, in accordance with the content in siloxane segments and their length. The sample PI1 shows the highest retention capacity for water vapors; the presence of the free carboxylic groups and low crosslinking density could explain this behavior [ 32 ]. The presence of the siloxane component does not inhibit the moisture sorption capacity in the samples containing polyimide [ 33 ].…”

Recent Advance in Low‐Dielectric‐Constant Organosilicon Polymers

“…It is worth noting that long‐chain siloxane units can cause the micro‐phase separation in PISs due to the difference of chain segment compatibility, which may have a negative impact on dielectric and mechanical properties. [ 97‐98 ]…”