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Structure and thermal transitions in a biomedically relevant liquid crystalline poly(ester amide).

ABSTRACT: There is still a need to develop bioresorbable polymers with high strength and high modulus for load-bearing biomedical applications. Here we investigate the liquid crystalline structural features of poly(desaminotyrosyl-tyrosine dodecyl dodecanedioate), poly(DTD DD), a new bioresorbable poly(ester amide) that is currently studied in vivo as a slow-degrading implantable biomaterial for load bearing applications. Thermally induced structural changes in poly(DTD DD) were studied using simultaneously differential scanning calorimetry (DSC) and X-ray scattering. The hexatic SmB organization of the polymer chains that exists at room temperature becomes progressively disordered upon heating, changing into a SmF phase and then into a smectic C phase at 60°C before turning into a free flowing melt at 130°C. X-ray scattering data and thermal analysis indicate the presence of a 2D ordered structure in the polymer melt. A structural model with an interesting 3-fold symmetry in the packing of the side chains around the rigid aromatic main chain, and the packing of these chains into fibrils is proposed. The liquid crystalline behavior of poly(DTD DD) makes it possible to melt process it at low temperatures without thermal degradation. This is a noteworthy advantage for the use of poly(DTD DD) as a high strength, readily processable, yet biodegradable polymer.

SUBMITTER: Bedoui F

PROVIDER: S-EPMC6827981 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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Structure and thermal transitions in a biomedically relevant liquid crystalline poly(ester amide).

Bedoui F F Murthy N S NS Kohn J J

Macromolecules 20170220 6

There is still a need to develop bioresorbable polymers with high strength and high modulus for load-bearing biomedical applications. Here we investigate the liquid crystalline structural features of poly(desaminotyrosyl-tyrosine dodecyl dodecanedioate), poly(DTD DD), a new bioresorbable poly(ester amide) that is currently studied <i>in vivo</i> as a slow-degrading implantable biomaterial for load bearing applications. Thermally induced structural changes in poly(DTD DD) were studied using simul ...[more]

PMID: 31686708

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Project description:The last decade has seen an exponential increase in the number of studies focused on novel applications for ionic liquids (ILs). Blends of polymers with ILs have been proposed for use in fuel cells, batteries, gas separation membranes, packaging, etc., each requiring a set of specific physico-chemical properties. In this work, blends of four grades of the poly(ether-ester) multiblock copolymer PolyActive™ with different concentrations of the CO2-philic 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][Tf2N] were prepared in the form of dense films by a solution casting and solvent evaporation method, in view of their potential use as gas separation membranes for CO2 capture. Depending on the polymer structure, the material properties could be tailored over a wide range by means of the IL content. All samples were dry-feeling, highly elastic self-standing dense films. The microstructure of the blends was studied by scanning electron microscopy with a backscattering detector, able to observe anisotropy in the sample, while a special topographic analysis mode allowed the visualization of surface roughness. Samples with the longest poly(ethylene oxide terephthalate) (PEOT) blocks were significantly more anisotropic than those with shorter blocks, and this heterogeneity increased with increasing IL content. DSC analysis revealed a significant decrease in the melting enthalpy and melting temperature of the crystalline PEOT domains with increasing IL content, forming an amorphous phase with Tg ? -50 °C, whereas the polybutylene terephthalate (PBT) phase was hardly affected. This indicates better compatibility of the IL with the polyether phase than the polyester phase. Young's modulus was highest and most IL-dependent for the sample with the highest PEOT content and PEOT block length, due to its high crystallinity. Similarly, the sample with short PEOT blocks and high PBT content also showed a high modulus and tensile strength, but much lower maximum elongation. This study provides a detailed discussion on the correlation between the morphological, thermal, and mechanical properties of these PolyActive™/[BMIM][Tf2N] blends.

Dataset Information

Structure and thermal transitions in a biomedically relevant liquid crystalline poly(ester amide).

Publications

Structure and thermal transitions in a biomedically relevant liquid crystalline poly(ester amide).

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