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Spontaneous Crosslinking of Poly(1,5-dioxepan-2-one) Originating from Ether Bond Fragmentation
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2008 (English)In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 46, no 21, 7258-7267 p.Article in journal (Refereed) Published
Abstract [en]

The spontaneous reaction of unsaturated double bonds induced by the fragmentation of ether bonds is presented as a method to obtain a crosslinked polymer material. Poly(1,5-dioxepan-2-one) (PDXO) was synthesized using three different polymerization techniques to investigate the influence of the synthesis conditions on the ether bond fragmentation. It was found that thermal fragmentation of the ether bonds in the polymer main chain occurred when the synthesis temperature was 140 degrees C or higher. The double bonds produced reacted spontaneously to form cross-links between the polymer chains. The formation of a network structure was confirmed by Fourier transform infrared spectrometry and differential scanning calorimetry. In addition, the low molar mass species released during hydrolysis of the DXO polymers were monitored by ESI-MS and MALDI-TOF-MS. Ether bond fragmentation also occurred during the ionization in the electrospray instrument, but predominantly in the lower mass region. No fragmentation took place during MALDI ionization, but it was possible to detect water-soluble DXO oligomers with a molar mass up to approximately 5000 g/mol. The results show that ether bond fragmentation can be used to form a network structure of PDXO.

Place, publisher, year, edition, pages
2008. Vol. 46, no 21, 7258-7267 p.
Keyword [en]
crosslinking, degradation, mass spectrometry, polyester-ethers, ring-opening polymerization, ring-opening polymerization, collision-induced dissociation, degradation-product patterns, ionization mass-spectrometry, epsilon-caprolactone, l-lactide, block-copolymers, 1, 5-dioxepan-2-one, hydrophilicity, polyglycols
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-17940DOI: 10.1002/pola.23037ISI: 000260587100035Scopus ID: 2-s2.0-55349110646OAI: oai:DiVA.org:kth-17940DiVA: diva2:335985
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Controlled Degradation of Polyester-Ethers Revealed by Mass Spectrometry Techniques
Open this publication in new window or tab >>Controlled Degradation of Polyester-Ethers Revealed by Mass Spectrometry Techniques
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The use of degradable biomedical materials in e.g. tissue engineering and controlled drug delivery has changed medical science during recent decades. The key question is to adapt the material with respect to mechanical properties, surface characteristics, and degradation profile to suit its intended application. Products formed during the degradation of bioresorbable materials are generally considered non-toxic and they are excreted from the human body. However, large amounts of specific degradation products such as hydroxyacids and oligomers may induce a pH decrease and a subsequent inflammatory response at the implantation site.

 

In this study, macromolecular design and a combination of cross-linking and adjusted hydrophilicity are utilized as tools to control and tailor the degradation rate and the subsequent release of degradation products from polyester-ethers. A series of different homo- and copolymers of e-caprolactone (CL) and 1,5-dioxepan-2-one (DXO) were synthesized and their hydrolytic degradation was monitored in aqueous media at 37 °C for up to 546 days. The low and medium molar mass degradation products released during hydrolysis were monitored by various mass spectrometry techniques. The materials studied included linear DXO/CL triblock and multiblock copolymers, PCL and PDXO linear homopolymers, and cross-linked homo- and random copolymers of CL/DXO where 2,2’-bis-(ε-caprolactone-4-yl) propane (BCP) was used as a cross-linking agent.

 

The results show that macromolecular engineering and controlled hydrophilicity of cross-linked networks are useful tools for customizing the release rate of acidic degradation products. Thereby, the formation of local acidic environments is prevented and the risk of inflammatory responses in the body is reduced.

Abstract [sv]

Läkarvetenskapen har under de senaste årtiondena förändrats genom användandet av nedbrytbara biomedicinska material inom t.ex. vävnadsersättning och kontrollerad läkemedelsfrisättning. Nyckeln är att anpassa materialets mekaniska egenskaper, ytegenskaper och nedbrytningsprofil för den tilltänkta tillämpningen. Produkterna som bildas under nedbrytningen av bioresorberbara material anses generellt vara icke-toxiska och utsöndras ur människokroppen, men stora mängder specifika nedbrytningsprodukter som t.ex. hydroxysyror kan orsaka en pH-sänkning och därmed en inflammatorisk reaktion vid implantationsplatsen.

 

I detta arbete används makromolekylär design och en kombination av tvärbindning och anpassad hydrofilicitet som verktyg för att kontrollera och skräddarsy nedbrytningshastigheten och den efterföljande frisättningen av nedbrytningsprodukter från polyester-etrar. En serie av olika homo- och sampolymerer av e-kaprolakton (CL) och 1,5-dioxepan-2-on (DXO) syntetiserades och deras hydrolytiska nedbrytning studerades i vattenlösning vid 37 °C i upp till 546 dagar. De låg- och medelmolekylära nedbrytningsprodukterna som frisattes under hydrolysen analyserades med olika masspektrometritekniker. Materialen som undersöktes inkluderade linjära DXO/CL triblock- och multiblocksampolymerer, linjära PCL och PDXO homopolymerer, samt tvärbundna homo- och slumpvisa sampolymerer av CL och DXO där 2,2’-bis(e-kaprolakton-4-yl)propan (BCP) användes som tvärbindare.

 

Resultaten visar att makromolekylär design och tvärbundna nätverk med kontrollerad hydrofilicitet är användbara verktyg för att skräddarsy frisättningshastigheten av sura nedbrytningsprodukter. Därmed kan bildandet av lokalt sura miljöer förhindras och risken för inflammatoriska reaktioner i kroppen minskas.

 

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. 59 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2008:57
Keyword
Degradation products, biocompatibility, -caprolactone, 1, 5-dioxepan-2-one, 6-hydroxyhexanoic acid, 3-(2-hydroxyethoxy)propanoic acid, oligomers
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-4898 (URN)978-91-7415-098-8 (ISBN)
Public defence
2008-09-26, F3, KTH, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100812Available from: 2008-09-17 Created: 2008-09-17 Last updated: 2010-08-12Bibliographically approved

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