Relaxation of polymer thin films in isothermal temperature-jump measurements

Extending Dynamic Range of Block Copolymer Ordering with Rotational Cold Zone Annealing (RCZA) and Ionic Liquids

“…The peak at the higher CZA speed of ∼30 μm/s is attributed to the sharp temperature gradient at high speed appears like a step-height annealing to the as-cast film that induces an instantaneous (in seconds) rapid normal expansion of the film. Under oven annealing this rapid perpendicular expanded stressed film can relax with time on order of minutes and hours to an isotropic relaxation state . We have shown that this rapid thermal expansion stress effect in oven annealing leads to modest perpendicular orientation (65%) at short times (∼5 min at 180 °C), followed by loss of perpendicular order to parallel orientation at long time (∼ hours) in our BCP system .…”

Extending Dynamic Range of Block Copolymer Ordering with Rotational Cold Zone Annealing (RCZA) and Ionic Liquids

“…The peak at the higher CZA speed of ∼30 μm/s is attributed to the sharp temperature gradient at high speed appears like a step-height annealing to the as-cast film that induces an instantaneous (in seconds) rapid normal expansion of the film. Under oven annealing this rapid perpendicular expanded stressed film can relax with time on order of minutes and hours to an isotropic relaxation state . We have shown that this rapid thermal expansion stress effect in oven annealing leads to modest perpendicular orientation (65%) at short times (∼5 min at 180 °C), followed by loss of perpendicular order to parallel orientation at long time (∼ hours) in our BCP system .…”

Through-Thickness Vertically Ordered Lamellar Block Copolymer Thin Films on Unmodified Quartz with Cold Zone Annealing

“…Apparently CZA-S induces such a high enough strain gradient in the l -BCP film at 48 °C mm –1 at 20 μm s –1 . The macroscopic rapid film expansion phenomenon is analogous to a study by Beaucage et al wherein an abrupt normal thermal expansion of a homopolymer film occurs from a thermal shock when the film is rapidly brought to a temperature above T g .…”

Ordering Pathway of Block Copolymers under Dynamic Thermal Gradients Studied by in Situ GISAXS

“…As seen in Figure 5, initial ordering takes place from T g upto T max and thereafter early stage of vitrification is observed from T max (205°C) till about 160°C. In this phase, as the temperature decreases, it leads to an increase in the Flory-Huggins interaction parameter between PS and PMMA (since χ ~1/T) 49 as shown in Supporting Information Figure S.1. Therefore, vitrification kinetics coupled with an increasing interaction parameter in Regime IV leads to an increased correlation length and grain coarsening.…”

“…In a conventional (oven) thermal annealing process for the PS- b -PMMA system, the preferential wetting of the PMMA over the native-oxide-covered quartz and polymer relaxation over long annealing times are competing factors that favor a horizontal (parallel to substrate) orientation of the microdomains over vertical ordering. However, for a CZA-S sweep performed in the velocity range 5–15 μm/s, the normal expansion-induced strain gradient dominates over preferential wetting, and the annealing times (above T g ) are lower than typical polymer relaxation time, , leading to a strong bias for vertical orientation of the PMMA cylinders.…”

“…At a given annealing temperature, the correlation length scales with time according to a power law (ξ ∼ t n ) . Correlation lengths on the order of 300–500 nm have been obtained for hexagonally packed vertical cylinders in surface studies of very thin (30–100 nm) films of cBCPs, annealed for 10 3 –10 5 s on surface modified (neutral brush grafted) substrates. ,,, However, as the film thickness increases beyond 300 nm, the effect of the surface modification within the bulk of the film reduces, leading to changes in the orientation of the cylinders, mismatch of cylindrical structures, and rapidly falling ξ . It is noteworthy that the correlation lengths (∼200 nm) obtained here using CZA-S are for a much (∼3×) thicker film (∼1 μm) but comparable to previous studies on grain coarsening in vertically oriented thin cBCP films using conventional thermal annealing.…”

Extending Dynamic Range of Block Copolymer Ordering with Rotational Cold Zone Annealing (RCZA) and Ionic Liquids

“…The peak at the higher CZA speed of ∼30 μm/s is attributed to the sharp temperature gradient at high speed appears like a step-height annealing to the as-cast film that induces an instantaneous (in seconds) rapid normal expansion of the film. Under oven annealing this rapid perpendicular expanded stressed film can relax with time on order of minutes and hours to an isotropic relaxation state . We have shown that this rapid thermal expansion stress effect in oven annealing leads to modest perpendicular orientation (65%) at short times (∼5 min at 180 °C), followed by loss of perpendicular order to parallel orientation at long time (∼ hours) in our BCP system .…”

Through-Thickness Vertically Ordered Lamellar Block Copolymer Thin Films on Unmodified Quartz with Cold Zone Annealing

“…Apparently CZA-S induces such a high enough strain gradient in the l -BCP film at 48 °C mm –1 at 20 μm s –1 . The macroscopic rapid film expansion phenomenon is analogous to a study by Beaucage et al wherein an abrupt normal thermal expansion of a homopolymer film occurs from a thermal shock when the film is rapidly brought to a temperature above T g .…”

Ordering Pathway of Block Copolymers under Dynamic Thermal Gradients Studied by in Situ GISAXS

“…As seen in Figure 5, initial ordering takes place from T g upto T max and thereafter early stage of vitrification is observed from T max (205°C) till about 160°C. In this phase, as the temperature decreases, it leads to an increase in the Flory-Huggins interaction parameter between PS and PMMA (since χ ~1/T) 49 as shown in Supporting Information Figure S.1. Therefore, vitrification kinetics coupled with an increasing interaction parameter in Regime IV leads to an increased correlation length and grain coarsening.…”

“…In a conventional (oven) thermal annealing process for the PS- b -PMMA system, the preferential wetting of the PMMA over the native-oxide-covered quartz and polymer relaxation over long annealing times are competing factors that favor a horizontal (parallel to substrate) orientation of the microdomains over vertical ordering. However, for a CZA-S sweep performed in the velocity range 5–15 μm/s, the normal expansion-induced strain gradient dominates over preferential wetting, and the annealing times (above T g ) are lower than typical polymer relaxation time, , leading to a strong bias for vertical orientation of the PMMA cylinders.…”

“…At a given annealing temperature, the correlation length scales with time according to a power law (ξ ∼ t n ) . Correlation lengths on the order of 300–500 nm have been obtained for hexagonally packed vertical cylinders in surface studies of very thin (30–100 nm) films of cBCPs, annealed for 10 3 –10 5 s on surface modified (neutral brush grafted) substrates. ,,, However, as the film thickness increases beyond 300 nm, the effect of the surface modification within the bulk of the film reduces, leading to changes in the orientation of the cylinders, mismatch of cylindrical structures, and rapidly falling ξ . It is noteworthy that the correlation lengths (∼200 nm) obtained here using CZA-S are for a much (∼3×) thicker film (∼1 μm) but comparable to previous studies on grain coarsening in vertically oriented thin cBCP films using conventional thermal annealing.…”

Extending Dynamic Range of Block Copolymer Ordering with Rotational Cold Zone Annealing (RCZA) and Ionic Liquids

“…The peak at the higher CZA speed of ∼30 μm/s is attributed to the sharp temperature gradient at high speed appears like a step-height annealing to the as-cast film that induces an instantaneous (in seconds) rapid normal expansion of the film. Under oven annealing this rapid perpendicular expanded stressed film can relax with time on order of minutes and hours to an isotropic relaxation state . We have shown that this rapid thermal expansion stress effect in oven annealing leads to modest perpendicular orientation (65%) at short times (∼5 min at 180 °C), followed by loss of perpendicular order to parallel orientation at long time (∼ hours) in our BCP system .…”

Through-Thickness Vertically Ordered Lamellar Block Copolymer Thin Films on Unmodified Quartz with Cold Zone Annealing

“…Apparently CZA-S induces such a high enough strain gradient in the l -BCP film at 48 °C mm –1 at 20 μm s –1 . The macroscopic rapid film expansion phenomenon is analogous to a study by Beaucage et al wherein an abrupt normal thermal expansion of a homopolymer film occurs from a thermal shock when the film is rapidly brought to a temperature above T g .…”

Ordering Pathway of Block Copolymers under Dynamic Thermal Gradients Studied by in Situ GISAXS

“…As seen in Figure 5, initial ordering takes place from T g upto T max and thereafter early stage of vitrification is observed from T max (205°C) till about 160°C. In this phase, as the temperature decreases, it leads to an increase in the Flory-Huggins interaction parameter between PS and PMMA (since χ ~1/T) 49 as shown in Supporting Information Figure S.1. Therefore, vitrification kinetics coupled with an increasing interaction parameter in Regime IV leads to an increased correlation length and grain coarsening.…”

“…In a conventional (oven) thermal annealing process for the PS- b -PMMA system, the preferential wetting of the PMMA over the native-oxide-covered quartz and polymer relaxation over long annealing times are competing factors that favor a horizontal (parallel to substrate) orientation of the microdomains over vertical ordering. However, for a CZA-S sweep performed in the velocity range 5–15 μm/s, the normal expansion-induced strain gradient dominates over preferential wetting, and the annealing times (above T g ) are lower than typical polymer relaxation time, , leading to a strong bias for vertical orientation of the PMMA cylinders.…”

“…At a given annealing temperature, the correlation length scales with time according to a power law (ξ ∼ t n ) . Correlation lengths on the order of 300–500 nm have been obtained for hexagonally packed vertical cylinders in surface studies of very thin (30–100 nm) films of cBCPs, annealed for 10 3 –10 5 s on surface modified (neutral brush grafted) substrates. ,,, However, as the film thickness increases beyond 300 nm, the effect of the surface modification within the bulk of the film reduces, leading to changes in the orientation of the cylinders, mismatch of cylindrical structures, and rapidly falling ξ . It is noteworthy that the correlation lengths (∼200 nm) obtained here using CZA-S are for a much (∼3×) thicker film (∼1 μm) but comparable to previous studies on grain coarsening in vertically oriented thin cBCP films using conventional thermal annealing.…”