Glass Transitions of Poly(methyl methacrylate) Confined in Nanopores: Conversion of Three- and Two-Layer Models

Li, Linling; Chen, Jiao; Deng, Weijia; Zhang, Chen; Sha, Ye; Cheng, Zhen Lei; Xue, Gi; Zhou, Dongshan

doi:10.1021/jp511248q

Cited by 41 publications

(56 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Recently, many research groups have devoted attention to exploration of the effects of AAO nanoconfinement, which alters physical, chemical, and mechanical properties, on molecular dynamics, molecular orientation, morphology transformation , and so forth. Especially, nanoconfinement effects on various geometries have been reported to influence the thermal glass transition of amorphous polymers . In this work, we investigated the influence of AAO nanocylindrical confinement on thermal property of PS (PS2), the PS nanofiber array with 50‐nm diameter and 50‐µm length that is fabricated by imprint temperature 200°C, pressure 5.0 MPa, and press time 30 min was used to investigate.…”

Section: Resultsmentioning

confidence: 99%

“…Figure shows the DSC heating curves of PS film and PS nanofiber array, PS film with the 40 µm of thickness has T g about 100°C while the T g of PS nanofiber array has higher T g of 104°C. Increasing of T g of the PS nanofiber arrays caused by polymer chains were squeezed in AAO confinement led to increasing the polymer chain packing density, also increasing of T g . Especially during molten polymer solidification after imprinting, strong interfacial interaction of the molten polymer and the AAO wall engenders the close‐packed form of polymer chains.…”

Section: Resultsmentioning

confidence: 99%

“…The molten polymer and polymer solution flowing ability depends strongly on filtration methods . Confinement of AAO porous walls alters the polymer molecular orientation and dynamics of polymer chains , and affects the nanostructure crystallization , glass temperature , polymer tacticity , and electron transportation . Modification of the AAO surface chemistry alters the polymer molecular chain orientation .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

One-dimensional polymer nanofiber arrays with high aspect ratio obtained by thermal nanoimprint method

et al. 2016

View full text Add to dashboard Cite

Polymer surface modification that mimicks natural behaviors has been a subject of great interest. Fabrication of polymer nanofiber arrays with various applications has been studied intensively. Avoidance of chemical solvents, reduction of processing time, improvement of the nanofiber size distribution and aspect ratios, and improvement of reproducibility have been sought for industrial value creation. This study examines an alternative fabrication methods for polymer nanofiber arrays using a combination of anodic aluminum oxide (AAO) nanoporous template and thermal nanoimprinting lithography for simple, precise processing. Based on those results, nanofiber arrays were fabricated with 40‐µm‐thick film and 50–100 nm fiber diameter polystyrene (PS) and polypropylene (PP). For this study, 50‐nm diameter PS nanofibers with 50 µm maximum length and a maximum aspect ratio of 1,000 were produced in addition to PP nanofibers having 130 µm maximum length and an aspect ratio of 2,600. The nanofiber lengths were affected considerably by molten polymer flow related to imprint processing conditions, polymer properties, AAO properties, and surface wettability between AAO and molten polymers. Moreover, AAO nanoconfinement demonstrated molecular orientation alignment of polymers that affect thermal properties, crystallinity, and mechanical properties of the obtained polymer nanofiber arrays. POLYM. ENG. SCI., 57:214–223, 2017. © 2016 Society of Plastics Engineers

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

One-dimensional polymer nanofiber arrays with high aspect ratio obtained by thermal nanoimprint method

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Polymer confinement in nanocomposites influences properties including the glass transition temperature ( T g ) of the polymer as well as the stiffness and viscoelastic behavior of the nanocomposites. Molecular polymer confinement can be achieved by filling polymer molecules into a nanoporous matrix with a pore size less than the bulk root‐mean‐square end‐to‐end distance of the polymer, which has been shown to reduce entanglements, form ordered morphology, influence T g , improve polymer diffusivity, and enhance fracture resistance of the nanocomposites .…”

Section: Introductionmentioning

confidence: 99%

Surface Chemical Functionalization to Achieve Extreme Levels of Molecular Confinement in Hybrid Nanocomposites

Wang

Isaacson

Wang

et al. 2019

Adv Funct Materials

View full text Add to dashboard Cite

Polymer confinement is realized in hybrid nanocomposites where individual polymer molecules are confined by a nanoporous matrix to dimensions less than the molecular size of the polymer. Here it is shown that by functionalizing the interior pore surfaces of a nanoporous organosilicate matrix, the pores can be filled with polystyrene molecules to achieve extreme levels of molecular confinement not previously possible. This provides opportunities for unique thermal and mechanical properties. It is shown that pore surface functionalization markedly impacts the polymer mobility during polymer infiltration by affecting the polymer-pore surface interaction, addressing the challenge of filling high-molecular-weight polymer molecules into nanoscaleconfined spaces. This allows for achieving extreme levels of molecular confinement with the loss of interchain entanglement and extensive polymer elongation along the pore axis. The glass transition temperature of the polymer is suppressed compared to bulk polymer melt, and is significantly affected by the polymer-surface interaction, which changes the polymer segmental mobility. The polymer-surface interaction also affects the interfacial polymer-pore sliding shear stress during polymer pullout from the nanopores, markedly affecting the fracture resistance of the nanocomposite.of the polymer, which has been shown to reduce entanglements, [4] form ordered morphology, [5] influence T g , [6] improve polymer diffusivity, [7] and enhance fracture resistance of the nanocomposites. [8] A fundamental limit of these studies, however, has been to achieve extreme levels of molecular confinement and the ability to control the interfacial interaction of the confined polymer with the matrix pores.Here we demonstrate that pore surface chemical functionalization allows us to achieve extreme levels of molecular confinement and manipulate the nanocomposite thermal and mechanical properties by controlling the interaction of the polymer with the pore surface (Figure 1). We show that the polymer filling rate can be significantly improved through selection of appropriate surface chemistry, which enables filling polymers with unprecedentedly high molecular weight (M w ) into the porous matrix to create extreme levels of molecular confinement not previously possible. This induces polymer hyperconfinement [[8a]] in which polymer chains entirely lose interchain entanglements and elongate extensively along the pore axis. [9] We also show that T g of the polymer is decreased by hyperconfinement, and can be significantly affected by tuning the polymer-surface interaction to impact the polymer segmental mobility.In addition, we show that the polymer-surface interaction affects the fracture of the nanocomposites where molecular bridging that involves the pullout and stretching of individual confined polymer chains from the nanopores leads to a marked increase in fracture resistance. The surface chemical functionalization significantly changes the sliding shear stress at the polymer/pore surface interfac...

show abstract

“…Three studies have employed DSC to investigate the T g -confinement behavior of polymer nanorods supported in anodic aluminum oxide (AAO) templates. 67,68,71 Li et al 67 reported that AAO-template-supported PMMA nanorods exhibited two T g 's, one higher and one lower than the bulk T g of the polymer. This was explained in terms of a two-layer model: polymer near the polymer-template interface possessed a higher T g due to attractive interactions 4 with the substrate, and polymer near the core of the nanorods possessed a lower T g due to poorer packing of the polymer chains.…”

Section: Introductionmentioning

confidence: 99%

Poly(methyl methacrylate) nanotubes in AAO templates: Designing nanotube thickness and characterizing the T-confinement effect by DSC

Tan

Torkelson

2016

Polymer

View full text Add to dashboard Cite

We used differential scanning calorimetry (DSC) to study the effect of confinement on the glass transition temperature (T g) of poly(methyl methacrylate) (PMMA) nanotubes supported in anodic aluminum oxide (AAO) templates. We created nanotubes by wetting templates with polymer melts and developed a design equation relating tube thickness (t tube) with bulk radius of gyration (R g): (t tube ≈ 2 R g + 9 nm). The results indicate that t tube depends on overall conformation and size of the polymer coils and can be tuned at the nanoscale by polymer molecular weight. The T g of AAO template-supported PMMA nanotubes increases with decreasing t tube , with T g,tube-T g,bulk = 12 K in 18-nm-thick nanotubes; we attribute the T g increase to hydrogen bonds between PMMA ester side groups and hydroxyl groups on the surface of the γ-Al 2 O 3 templates. Using ellipsometry, we characterized T g-confinement effects for PMMA films supported on Si/SiO x , sputtered Al 2 O 3 and sapphire (α-Al 2 O 3). Films supported on substrates with higher concentrations of surface hydroxyl groups (α-Al 2 O 3 > sputtered-Al 2 O 3 > Si/SiO x) exhibit larger T g-confinement effects. The DSC-determined T g enhancements for nanotubes supported in γ-Al 2 O 3 templates fall between the ellipsometry-determined T g enhancements determined for PMMA films on α-Al 2 O 3 and those for films on sputtered-Al 2 O 3. These results show that molecular weight provides for tunability of polymer nanotube thickness in AAO templates, that there is excellent agreement in confinement effects measured by DSC and by ellipsometry, and that T g can be tuned by modulating the levels of interfacial, polymer-substrate interactions by using surfaces with different chemical or crystallographic properties.

show abstract

Glass Transitions of Poly(methyl methacrylate) Confined in Nanopores: Conversion of Three- and Two-Layer Models

Cited by 41 publications

References 68 publications

One-dimensional polymer nanofiber arrays with high aspect ratio obtained by thermal nanoimprint method

One-dimensional polymer nanofiber arrays with high aspect ratio obtained by thermal nanoimprint method

Surface Chemical Functionalization to Achieve Extreme Levels of Molecular Confinement in Hybrid Nanocomposites

Poly(methyl methacrylate) nanotubes in AAO templates: Designing nanotube thickness and characterizing the T-confinement effect by DSC

Contact Info

Product

Resources

About