Nanochemistry through self-assembly : polymerisation of the organised phases of polyelectrolyte-surfactant complexes

Ganeva, Desislava Evgenieva (2003-12)

Thesis (PhD)--Stellenbosch University, 2003.

Thesis

ENGLISH ABSTRACT: The general objective of this research was to develop a new approach to direct templating, where the organised phases of polyelectrolyte-surfactant complexes are used as hosts for organic polymerisation reactions. The lamellar polyelectrolyte-surfmer complex of the tail-functionalised di (undecenyl) phosphate (roC11) and polydiallyldimethylammonium chloride (pDADMAC) was identified as a host for organic polymerisation reactions. The complex showed higher stability (than the one found in the case of roC11 alone) when used as a template, owing to the presence of the polyelectrolyte backbone. The mobility of the reactive groups (positioned in the tails of the surfmer) was not sufficient for homopolymerisation reactions to take place. Direct, 1:1 templating was only achieved on the incorporation of an unbound co-monomer (a dithiol) in the complex. Furthermore the thiol-ene polyaddition reaction used offered the advantage over conventional free radical polymerisation that volume shrinkage was largely avoided and possibilities for phase disruption minimised. The pDADMA I roC11 complex was able to withstand swelling with -35 wt % of thiol co-monomer (constituting a 1:1 ratio of thiol to vinyl groups) without signs of phase disruption. The obtained polymer symplexes were cured copies of the template proving that no phase disruption or disordering occurred during the polyaddition. These results were confirmed using X-ray scattering and microscopy. This is the first case of successful polyaddition within the organised phases of polyelectrolyte-surfactant complexes to be reported. The addition of a second co-monomer (a diene) to the reaction system provided a possibility by which to vary the composition of the novel composite materials obtained through the ternary thiol-ene polyaddition within the complex. it therefore allowed for the investigation of the effect of increasing the amount of guest polymer on the structure of the host polyelectrolyte-surfactant complex. The increased d-spacing of the host structure with the increase in guest polymer content gave the possibility to tune the material properties of those highly anisotropic networks. Onset of phase disruption was only observed with 72 wt% copolymer included within the host. This unusually high degree of swelling under preservation of nanoscale order could be attributed to the flexible, linear structure of the co-monomers used, since the addition of rigid comonomers was reported to cause phase disruption at only - 17 wt% of swelling of the host polyelectrolyte-surfactant complex.' The high loading capability of the pDADMA I roC11 allowed for a large amount of otherwise unstructured material to be organised within the template.

AFRIKAANSE OPSOMMING: Die doel van hierdie navorsing was om 'n nuwe benadering tot direkte afdrukvorming (Eng: templating) te ontwikkel, waar die georganiseerde fases van polielektroliet-seepkomplekse as gashere vir organiese polimerisasiereaksies gebruik is. Die lamellêre (Eng: lamellar) polielektroliet-seepkompleks van die eindfunksionele verbinding di(undekiel)fosfaat (coC11) en polidiallieldimetielammoniumcloried (pDADMAC) is as gasheer vir die organiese polimerisasiereaksies geïdentifiseer. Tydens gebruik van laasgenoemde vir afdrukvorming was die stabiliteit van die gevormde kompleks hoër as wanneer coC11 alleen gebruik is. Dit word toegeskryf aan die teenwoordigheid van die polielektrolietskelet. Die mobiliteit van die reaktiewe groepe (aan die punte van die seep/surfmer) was nie voldoende om homopolimerisasiereaksies te laat plaasvind nie. Direkte1:1 afdrukvorming is slegs bereik met die byvoeging van 'n ongebonde komonomeer ('n ditiol) tot die kompleks. Gebruik van die tiol-een addisiepolimerisasiereaksie was meer voordelig as konvensionele vryeradikaalpolimerisasie, aangesien volume-inkrimping grootendeels vermy is en die kanse vir fase-ontwrigting tot 'n mimimum beperk is. Die pDADMA / coC11 kompleks het swelling met -35 massa % tiol-komonomeer (bestaande uit 'n 1:1 verhouding van tiol tot viniel groepe) sonder enige tekens van faseversteuring weerstaan. Die polimeersimplekse wat verkry is, was gesette kopieë van die patroonvorm. Dit het bewys dat daar geen faseversteuring of ontordening gedurende die polimeeraddisie plaasgevind het nie. Hierdie bevindinge is d.m.v. X-straalverstrooiing en mikroskopie bevestig. Hierdie was die eerste keer dat meervoudige aanhegting binne-in die georganiseerde fases van polielektroliet-seepkomplekse suksesvol uitgevoer is. Die byvoeging van 'n tweede komonomeer ('n dieen) het die moontlikheid geskep om die samestelling van die nuwe saamgestelde materiale, wat d.m.v. ternêre ticl-een poliaddissie binne-in die kompleks verkry is, te varieer. Dit was gevolglik moontlik om die invloed van 'n toename in die hoeveelheid gaspolimeer op die struktuur van die gasheerpolielektroliet-seepkompleks te bepaal. Die toename in die d-spasiëring van die gas-struktuur, met die toename in gaspolimeerinhoud, het tot gevolg gehad dat die materiaaleienskappe verander kon word. Die aanvang van faseversteuring is opgemerk by 72 massa % kopolimeer in die gasheer. Die ongewone hoë swelling met behoud van die nano-skaalorde, is toegeskryf aan die buigbare, liniêre struktuur van die komonomere wat gebruik is. Volgens die literatuur het die byvoeging van starre komonomere alreeds faseversteuring by slegs - 17 massa % swelling van die gasheer polielektroliet-seepkompleks veroorsaak. Die hoë ladingskapasiteit van die pDADMA I coC11 het daartoe aanleiding gegee dat 'n groot hoeveelheid andersins ongestruktureerde materiaal binne-in die templaat gestruktureer kon word.

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