[PDF] Synthesis And Self Assembly Of Biodegradable Polylactide Containing Block Copolymers And Their Stereocomplex Blends eBook

Author : Lu Sun
Publisher :
Page : 262 pages
File Size : 18,46 MB
Release : 2007
Category :
ISBN :

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Polylactide (PLA), as an emerging biodegradable thermoplastic material derived from renewable resources, has attracted increasing research interest due to its biodegradability and biocompatibility. PLA containing block copolymers further diversify its application in the biomedical field, commodity materials, and even advanced nanoporous materials.

Author : Jie Ren
Publisher : Springer Science & Business Media
Page : 314 pages
File Size : 18,4 MB
Release : 2011-04-05
Category : Technology & Engineering
ISBN : 3642175961

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"Biodegradable Poly (Lactic Acid): Synthesis, Modification, Processing and Applications" describes the preparation, modification, processing, and the research and applications of biodegradable poly (lactic acid), which belong to the biomedical and environment-friendly materials. Highly illustrated, the book introduces systematically the synthesis, physical and chemical modifications, and the latest developments of research and applications of poly (lactic acid) in biomedical materials. The book is intended for researchers and graduate students in the fields of materials science and engineering, polymer science and engineering, biomedicine, chemistry, environmental sciences, textile science and engineering, package materials, and so on. Dr. Jie Ren is a professor at the Institute of Nano and Bio-Polymeric Materials, School of Material Science and Engineering, Tongji University, Shanghai, China.

Author : Nikolaos Petzetakis
Publisher :
Page : pages
File Size : 11,90 MB
Release : 2012
Category :
ISBN :

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Chapter 1 is the main introduction of this work and it features the two main concepts of this study. First living polymerisation techniques are introduced with a special focus into RAFT and ROP. Secondly solution self-assembly is briefly discussed. In Chapter 2 we describe the synthesis of an amphiphilic block copolymer where the two blocks are connected through a reversible bond. A Diels-Alder (DA) adduct consisted of a maleimide-furan pair was chosen as the reversible linker. The solution self-assembly of this polymer was studied by TEM and DLS giving rise to the unexpected formation of cylindrical micelles. In Chapter 3 the main objective was to synthesise new amphiphilic block copolymers without the DA motif in order to investigate their self-assembly behaviour compared to those for DA containing polymers obtained in Chapter 2. To further understand this self-assembly behaviour our method has been extended to the synthesis of other hydrophilic blocks and end group modified polymers. In addition, some key properties of the polymers synthesised have been investigated. In Chapter 4 our main goal is to understand the origins of the cylindrical micelle formation seen in Chapter 2. We investigated the aggregation behaviour under the aqueous thermal conditions in which the PTHPA block hydrolysis is performed. Studies at different concentrations and solvent mixtures provide valuable information regarding the self-assembly mechanism. In addition, the polymers with modified end groups and the triblock copolymers synthesised in Chapter 3 are studied and all the results compared. In Chapter 5 we explore the living crystallisation driven self-assembly of PLA-b- PAA block copolymers in aqueous media towards the formation of cylindrical micelles of controlled length. Interestingly, in many of the unstained TEM images presented in this work the particles demonstrate a non-uniform contrast along their width. This unexpected result is fully investigated in Chapter 6.

Author : Lauren Cowie
Publisher :
Page : pages
File Size : 13,85 MB
Release : 2013
Category :
ISBN :

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Biocompatible and biodegradable poly(lactide)-2-methacryloyloxyethyl phosphorylcholine (PLA-PMPC) amphiphilic block copolymers were synthesized by a combination of Ring Opening Polymerization (ROP) and Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization techniques. The PLA-macroRAFT agent was synthesized by the derivatization of PLA-OH with RAFT agent 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (CPADB) achieving high levels of functionalization and narrow weight distributions (PDI range of 1.02-1.17). PLA-PMPC with varied MPC block lengths were synthesized yielding polymers with a narrow polydispersity PDI = 1.16-1.21. Triblock copolymers PMPC-PLA-PMPC with varying hydrophilic weight ratios were synthesized following an analogous method, the polymerizations were shown to be controlled with PDI's of 1.24 and 1.36. PLA-PMPC block copolymers with varied compositions were self-assembled using several techniques to target different morphologies. Nanostructures were characterised by DLS and TEM. Block copolymers with a larger PLA block length were shown to generate smaller aggregates i.e. micelles. The morphologies observed for the various block copolymers were consistent amongst different preparative techniques. Vesicle structures were reproducible by the self-assembly of PMPC50-PLA51-PMPC50, however, by preparing nanoparticles by direct dissolution micelles formed. The block copolymers were shown to encapsulate a hydrophobic dye in aqueous media thereby demonstrating its potential drug delivery applications.

Author : Liying Wang
Publisher :
Page : 73 pages
File Size : 30,62 MB
Release : 2018
Category : Block copolymers
ISBN :

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Polylactide (PLA) is an important biodegradable, biocompatible and renewable material that has been studied for many years for biomedical applications such as tissue scaffolding and surgical sutures. The research project described in this Thesis focused on the synthesis of polylactide-block-polylysine (PLA-b-PLy) amphiphilic block copolymers designed for use in targeted drug delivery systems. Block copolymers with a cleavable, redox-sensitive disulfide bond at the block junction, as well as non-cleavable block copolymers were synthesized for comparison. The molecular weight of the PLA and the PLy blocks in the copolymers was varied, so as to control their hydrophobic/hydrophilic balance, and ultimately their self-assembly behavior. A novel redox-sensitive initiator, tert-butyl (2-((2-hydroxyethyl)disulfanyl)ethyl) carbamate, was used to generate the redox-sensitive copolymers, whereas (3-(Boc-amino)-1-propanol served for the non-cleavable systems. The hydroxyl group of these compounds was activated with the non-metallic catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene/benzoic acid (DBU/BA) to initiate the ring-opening polymerization (ROP) of lactide. After the polymerization of lactide and removal of the Boc protecting group at the end of the PLA chain, the free primary amine functionality was used to initiate the ring-opening polymerization of N6-carbobenzoxy-L-lysine N-carboxyanhydride (Z-protected L-lysine NCA monomer). Sample analysis by size exclusion chromatography (SEC) and proton nuclear magnetic resonance (1H NMR) spectroscopy confirmed that the block copolymers had low polydispersity indices (PDI) and the expected molecular weights. Deprotection of the Z-lysine units of the copolymers was accomplished with HBr, but degradation of the PLA segment could not be avoided under the reaction conditions investigated. It is suggested that future investigations either rely on a different deprotection method for the Z-group, or that a different protecting group be used in the NCA monomer serving to build the PLy block.

Author : Kristoffer Keith Stokes
Publisher :
Page : 282 pages
File Size : 27,30 MB
Release : 2007
Category :
ISBN :

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Linear-dendritic block copolymers consisting of a poly(styrene) linear block and poly(amidoamine) dendrimer block were synthesized and examined for their ability to self-assemble in both aqueous environments and organic/aqueous mixtures. These polymers were shown to assemble into vesicle structures under a variety of conditions. Furthermore, size measurements of the dendritic portion were taken by means of Langmuir-Blodgett isotherms, demonstrating both the steric area, as well as the electrostatic area occupied by the dendrimer in a monolayer. Further studies into the rapid synthesis of such systems were also undertaken, with a particular interest in use of the so-called "click" reaction to be used as a facile means toward block copolymer synthesis.