Brewster Angle Microscopy Study of Poly(ε-caprolactone) Crystal Growth in Langmuir Films at the Air/Water Interface

Abstract

Surface pressure-induced crystallization of poly(epsilon-caprolactone) (PCL) from a metastable region of the surface pressure-area per monomer (Pi-A) isotherm in Langmuir monolayers at the air/water (A/W) interface has been captured in real time by Brewster angle microscopy (BAM). Morphological features of PCL crystals grown in Langmuir films during the compression process exhibit four fully developed faces and two distorted faces. During expansion of the crystallized film, polymer chains slowly detach from the crystalline domains and diffuse back into the monolayer as the crystals "melt". Typical diffusion-controlled morphologies are revealed by BAM during the melting process as the secondary dendrites melt away faster, that is, at a higher surface pressure than the principal axes. Electron diffraction on Langmuir-Schaefer films suggests that the lamellar crystals are oriented with the polymer chain axes perpendicular to the substrate surface, while atomic force microscopy reveals a crystal thickness of approximately 7.6 nm.

Polymer Crystallization on the Surface of Water or Aqueous Salt Solution

“…Thus, at this point at least five monomer units have to be stacked on top of each other. It should be mentioned that this isotherm of low-molar-mass PCL is similar to the results obtained by Esker et al [13]. of the PCL under investigation does not have any influence on the crystal morphology when compared to the data of Esker et al [13].…”

“…It should be mentioned that this isotherm of low-molar-mass PCL is similar to the results obtained by Esker et al [13]. of the PCL under investigation does not have any influence on the crystal morphology when compared to the data of Esker et al [13]. These single crystals can be transferred onto solid supports using the LB technique.…”

“…A comprehensive study of the crystallization of medium-and highmolar-mass PCL on the water surface was done by Esker et al including Langmuir trough studies, BAM, and after LangmuirBlodgett (LB) transfer onto solid substrates atomic force microscopy (AFM) and electron diffraction studies [13]. The crystallization on the water surface is partially reversible and the crystals dissolve during expansion.…”

Magnetic field responsive methylcellulose-polycaprolactone nanocomposite gels for targeted and controlled release of 5-fluorouracil

“…Following efforts to find new synthetic polymers that were degradable by microorganisms, PCL became commercially available and recently, it has propelled into biomaterials area more rapidly [15]. PCL is a semicrystalline, aliphatic polyester with low glass transition temperature and melting point and it has good biocompatibility and degradability [16][17][18][19]. PCL is not biodegradable in the body of animals and human because of the lack of suitable enzymes [20].…”

The relevance of hydrophobic segments in multiblock copolyesterurethanes for their enzymatic degradation at the air-water interface

“…The surface pressure-area (p-A) isotherms indicate transition regions which are typical for the coexistence of liquid expanded (LE) and liquid condensed (LC) phases and becomes broader with increasing OCL content (PDLCL50: 7.5e20 Å 2 ; PDLCL70: 5e22 Å 2 ) (Fig. 1) [33,34]. Homogeneous films are revealed by BAM images in the semi-diluted state for all investigated polymers allowing to perform LMD studies.…”