Effective Viscosity of Unentangled Random Copolymer Films of Styrene and 4-Methoxystyrene with Different Copolymer Compositions

Xu, Jianquan; Lv, Chao; Du, Binyang; Wang, Xinping; Tsui, Ophelia Kwan Chui

doi:10.1021/acs.macromol.0c01394

Cited by 12 publications

(15 citation statements)

References 75 publications

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“…With the three mechanosynthesized monomers in hand, preliminary free radical polymerizations (FRPs) were carried out at 70 °C in bulk using azobis(isobutyronitrile) (AIBN) as an initiator (0.005 mol % with respect to the substrate). Those reactions yielded three polystyrene-type polymers − bearing one, two, or three methoxy (MeO) functional groups, respectively, PVMB , PVDMB , and PVTMB . Their number-average molar mass ( M n ), dispersity ( Đ ), glass transition temperature ( T g ), and thermal decomposition temperature ( T d ) are gathered in Table .…”

Section: Results and Discussionmentioning

confidence: 99%

Mechanosynthesis and Polymerization of Biosourced Styrene Derivatives Based on Building Blocks of Lignin

Michalska-Walkowiak,

SN Antonio,

Coumes

et al. 2024

ACS Sustainable Chem. Eng.

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Finding and developing new biosourced materials that can compete with the current petro-sourced ones are a top priority in order to transition to a more sustainable society. Although the preparation of biosourced polyesters or polyamides is quite well described, finding biosourced and sustainable alternatives to petro-sourced polystyrene is still challenging. Herein, we report the synthesis of polystyrenes prepared in three steps from vanillin, 4-hydrobenzaldehyde, and syringaldehyde, compounds that can be obtained through lignin depolymerization under oxidative conditions. The synthesis involves the conversion of these biosourced platforms into polymerizable styrene derivatives through a methylation of the hydroxyl group followed by an olefination of the aldehyde function. The monomers were first synthesized under conventional conditions using solvents. Then, the synthesis was improved from the sustainability point of view by using a ball mill under solventless conditions, generating much less waste in the process. The three monomers were then converted into biosourced homopolymers through free radical polymerization in bulk, providing functional polystyrene derivatives with thermal properties comparable to those of common petro-sourced polystyrene.

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Section: Results and Discussionmentioning

confidence: 99%

Mechanosynthesis and Polymerization of Biosourced Styrene Derivatives Based on Building Blocks of Lignin

Michalska-Walkowiak,

SN Antonio,

Coumes

et al. 2024

ACS Sustainable Chem. Eng.

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“…The past three decades have witnessed intense research focused on nanoscale confinement effects of polymeric glass-formers. − Studies have reported that a broad range of properties, including the glass-transition temperature ( T g ), − surface viscosity, − small-mole...…”

Section: Introductionmentioning

confidence: 99%

Reducing the Bulk Fragility and Suppressing the Fragility-Confinement Effect in Polystyrene with Very Low Levels of 2-Ethylhexyl Acrylate Comonomer

et al. 2023

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The effects of nanoconfinement on the glasstransition temperature (T g ) and fragility index (m) of thin polymer films, e.g., polystyrene (PS), can be substantial. We recently demonstrated the elimination of the T g -confinement effect in supported PS films by including 2−6 mol % 2-ethylhexyl acrylate comonomer (Macromolecules 2022, 55, 9601). Here, we use spectroscopic ellipsometry and differential scanning calorimetry to characterize how m is affected by inclusion of low levels of 2ethylhexyl acrylate (EHA), n-butyl acrylate (nBA), or n-octyl acrylate (nOA) in styrene (S)-based random copolymers. Relative to PS, the inclusion of 1 mol % EHA or 5 mol % nBA or nOA in Sbased copolymers has no effect within uncertainty on bulk fragility, m bulk . In contrast, 98/2 mol % and 94/6 mol % S/EHA copolymers exhibit ∼21% and ∼30% reductions in m bulk relative to PS. In thin films supported on silicon, PS, 99/1 mol % S/EHA, 95/5 mol % S/nOA, and 95/5 mol % S/nBA exhibit similar, strong confinement effects on T g and m. In contrast, 98/2 mol % S/EHA exhibits weak m-confinement effects in sub-100 nm thick films, and 94/6 mol % S/EHA shows no effect down to 22 nm. The strengths of the T g -confinement effect for various systems are in accord with the m-confinement effects. Thus, the role of the EHA comonomer in suppressing or eliminating T g -and m-confinement effects cannot be generalized to other acrylates. These results support previously reported correlations between the susceptibilities of T g -and m-perturbations caused by nanoconfinement and provide a very simple route to suppress or eliminate confinement effects in linear polymers.

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“…Numerous experiments have shown that the molecular motions near the surface of polymers − and molecular glasses , are faster than those in bulk. Moreover, the enhanced near-surface motions can have a significant impact on the properties of thin polymer films, including their mechanical properties, − viscosity, ,− glass transition temperature ( T g ), − dielectric relaxations, − thermal expansivity, , and dewetting phenomena. − The prevalent model used to describe the thickness ( h ) dependence of the properties of polymer filmsthe layer modelusually assumes that the properties on the film surface do not vary with h. , However, few experiments ,, have investigated whether the surface dynamics is modified when h is decreased below the distance over which enhancement in the near-surface dynamics sustains (ca. 1–1000 nm).…”

Section: Introductionmentioning

confidence: 99%

Glass Transition of the Surface Monolayer of Polystyrene Films: Effect of Thermal Preannealing

Yan

et al. 2023

Macromolecules

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In a previous experiment, we observed that the glass transition temperature of the surface monolayer glass transition temperature (T g surf ) of unannealed polystyrene (PS) films spin-coated on oxide-coated silicon decreased with decreasing film thickness (h < ∼60 nm). However, this h dependence could be removed by thermal preannealing. In this experiment, we investigated the origin of this preannealing effect. We found that T g surf of the thin films increased with preannealing time (t ANN ) and reached the steady-state thick-film value at a characteristic time (τ surf ) following the τ surf ∼ h 2 scaling for diffusion. Moreover, chain adsorption occurred alongside the increase in T g surf during thermal preannealing and reached the steady-state adsorbed amount at a time similar to τ surf . We tentatively suggest that the observed increase in T g surf with t ANN was caused by diffusion of free-volume holes from the polymer−substrate interface to the free surface due to densification of the interfacial polymer upon chain adsorption.

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Effective Viscosity of Unentangled Random Copolymer Films of Styrene and 4-Methoxystyrene with Different Copolymer Compositions

Cited by 12 publications

References 75 publications

Mechanosynthesis and Polymerization of Biosourced Styrene Derivatives Based on Building Blocks of Lignin

Mechanosynthesis and Polymerization of Biosourced Styrene Derivatives Based on Building Blocks of Lignin

Reducing the Bulk Fragility and Suppressing the Fragility-Confinement Effect in Polystyrene with Very Low Levels of 2-Ethylhexyl Acrylate Comonomer

Glass Transition of the Surface Monolayer of Polystyrene Films: Effect of Thermal Preannealing

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