Metastable Isotactic Poly(methyl methacrylate) Prepared by Freeze-Extracting Solutions in Poly(ethylene glycol)

Zhou, Dongshan; Li, Liang; Che, Bo; Cao, Qin Bo; Lu, Yun; Xue, Gi

doi:10.1021/ma0493978

Cited by 20 publications

(28 citation statements)

References 19 publications

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“…Isotactic PMMA is a very slowly crystallizing polymer. The freeze‐drying method was used to obtain PMMA samples from solutions (0.5–15 wt%) in poly(ethylene glycol) or dioxane . A low crystallinity of the extracted samples was increased by annealing at T g temperature, however the effect depended on the solvent used and the concentration of the polymer in solution.…”

Section: Process Of Re‐entanglingmentioning

confidence: 99%

The Entanglements of Macromolecules and Their Influence on the Properties of Polymers

Pawlak

2019

Macro Chemistry & Physics

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Macromolecules form entanglements, the presence of which determines many of the polymer's properties; in solution, melt, and solid state. In this review, how the properties of polymers (rheological, thermal, and mechanical), depend on the concentration of the entanglements, is discussed. Although a typical polymer is characterized by the equilibrium density of entanglements, there are methods that can be applied for the reduction of this density. The methods used most often include dissolving a polymer and rapid freezing, crystallization during polymerization, and crystallization from a cooled dilute solution. The properties of disentangled polymers are significantly different from the properties of fully entangled polymers. These properties are discussed in relation to their dependence on the density of the entanglements. The disentangled material can be re‐entangled by the annealing of the polymer; however, reaching the equilibrium density of the entanglements is usually a slow process. It means that a polymer may be processed without losing its disentanglements. The properties of the re‐entangled polymer are usually close to the properties of the initial polymer.

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Section: Process Of Re‐entanglingmentioning

confidence: 99%

The Entanglements of Macromolecules and Their Influence on the Properties of Polymers

Pawlak

2019

Macro Chemistry & Physics

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“…31,32 These results indicate that the interfacial rearrangements of it-PMMA chains that occurred in films were driven by the mixed solvent, whereas it-PMMA crystallization was driven by annealing at high temperature or under compression in previous studies. [11][12][13][14][15][16][17][18][19] The crystallized it-PMMA thin films can incorporate st-PMAA, most likely because further interfacial rearrangements also occurred in these films. Therefore, the morphological changes of the porous thin films during it-PMMA crystallization and the subsequent st-PMAA incorporation were initially analyzed by SEM and AFM.…”

Section: Resultsmentioning

confidence: 99%

“…10 The crystallization of it-PMMA films has been researched by annealing at elevated temperatures for more than a few days, or under compres-sion. [11][12][13][14][15][16][17][18][19] Most of these studies focused mainly on structural analyses of the crystals using infrared (IR) spectroscopy and X-ray diffraction (XRD), but the morphology of crystallized it-PMMA films has also been studied for a long time. 11,12,16,18 The film-formation methods used were either solvent evaporation from solution-cast films or the Langmuir-Blodgett technique as described below.…”

Section: Introductionmentioning

confidence: 99%

“…2,33 The crystallization of it-PMMA occurred merely by immersing the porous films in a mixed solvent of acetonitrile/water (4/6, v/v) at room temperature, which is a different procedure and milder than conventional conditions. [11][12][13][14][15][16][17][18][19] Furthermore, st-PMAA incorporation into porous it-PMMA films was analyzed at the molecular level by QCM. Porous it-PMMA films incorporated st-PMAA with increasing acetonitrile content in the st-PMAA solution.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Morphological changes of isotactic poly(methyl methacrylate) thin films via self-organization and stereocomplex formation

Kamei

Ajiro

Akashi

2009

Polym J

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Morphological changes of macromolecularly porous thin films during isotactic (it) poly(methyl methacrylate) (PMMA) crystallization and the subsequent syndiotactic (st) poly(methacrylic acid) (PMAA) incorporation are described herein. Porous it-PMMA thin films were prepared on a gold substrate by the selective extraction of st-PMAA from stereocomplex films composed of it-PMMA/st-PMAA using layer-by-layer assembly. it-PMMA crystallization occurred when the porous it-PMMA films were immersed in a mixed solvent of acetonitrile/water (4/6, v/v). Surface analyses of films were performed by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS) and static contact angles. Dotted aggregates of it-PMMA appeared on crystallized films, whereas networks composed of crystallized it-PMMA and the stereocomplex were observed on st-PMAA incorporated films. Gold substrate peaks were observed not on porous it-PMMA films, but on crystallized it-PMMA films by XPS, indicating that homogeneously broadened it-PMMA in porous films was localized because of its crystallization. The static contact angle of crystallized it-PMMA films was 36.5 ± 1.61, which was smaller than that of porous it-PMMA films (49.2 ± 1.91). This difference resulted from the surface morphology of the thin films. Dotted it-PMMA aggregates were also observed when spin-coated films were immersed in the mixed solvent.

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“…It is generally known that solvent molecular size is an important factor that determines the structure and properties of polymer solution. Xue and coworkers have studied the effect of solvent molecular size, and found that the solvent with large molecule volumes, such as poly(ethylene glycol) (PEG) oligomers or dioctyl phthalate (DOP) can reduce entanglement and enhance the crystallizability of polymer chains in solvents 1–4. Spontak et al observed that the size of the nanoscale solvent added to the ABA triblock copolymer can drive the interfacial segregation and center alignment by using the self‐consistent field theory (SCFT) 5.…”

Section: Introductionmentioning

confidence: 99%

Effect of Solvent Molecular Size on the Self‐Assembly of Amphiphilic Diblock Copolymer in Selective Solvent

Jiang

2009

Macro Theory & Simulations

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Real‐space self‐consistent field theory (SCFT) is employed to study the effect of solvent molecular size on the self‐assembly of amphiphilic diblock copolymer in selective solvent. The phase diagrams in wide ranges of interaction parameters and solvent molecular size were obtained in present study. The results indicate that the solvent molecular size is a key factor that determines the self‐assembly of amphiphilic diblock copolymer. The self‐assembled morphology changes from circle‐like micelle to line‐like micelle, then to loop‐like micelle by decreasing the solvent molecular size in a wide range of solvent selectivity. We analyze and discuss this change in terms of the solvent solubility and the entropy contribution.magnified image

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Metastable Isotactic Poly(methyl methacrylate) Prepared by Freeze-Extracting Solutions in Poly(ethylene glycol)

Cited by 20 publications

References 19 publications

The Entanglements of Macromolecules and Their Influence on the Properties of Polymers

The Entanglements of Macromolecules and Their Influence on the Properties of Polymers

Morphological changes of isotactic poly(methyl methacrylate) thin films via self-organization and stereocomplex formation

Effect of Solvent Molecular Size on the Self‐Assembly of Amphiphilic Diblock Copolymer in Selective Solvent

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