MALDI−TOF Mass Spectral Characterization of Polymers Containing an Azide Group: Evidence of Metastable Ions

Li, Yejia; Hoskins, Jessica N.; Sreerama, Subramanya Gupta; Grayson, Scott M.

doi:10.1021/ma100599n

Cited by 80 publications

(82 citation statements)

References 52 publications

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“…The precursor linear polymer (L-PCL-OH) can be used as a linear analog that has almost the same molecular weight as the synthesized C-PCL. Reprinted with permission from [48] the cyclic chain (as shown in Scheme 1) that is not present in the linear chains; hence, the slight difference in M n values obtained by MALDI-TOF [58]. Table 1 shows two types of linear precursors for PCL (L-PCL-OH and L-PCL-Acet).…”

Section: Types Of Cyclic Polymersmentioning

confidence: 99%

Crystallization of Cyclic Polymers

Pérez-Camargo

Múgica

Zubitur

et al. 2015

Polymer Crystallization I

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The effect of chain topology (ring versus linear polymer chains) on polymer crystallization is reviewed. Recent advances in ring closure and ring expansion synthetic techniques have made available a range of well-characterized samples with higher levels of purity than available decades ago. Cyclic molecules are fascinating because the structural difference between them and linear chains is relatively small, yet their behavior can be completely different from that of their linear analogs of identical chain length. The effect of having no chain ends can dramatically change the polymer coil conformation and diffusion rate, as well as the chain entanglement density in the melt. These changes are reflected in different nucleation and crystallization kinetics for cyclic and linear polymeric chains. However, the results published so far seem to be dependent on the type of polymer employed. Therefore, a careful look at the literature and evidence reported for each group of materials has been assembled and compared. The possible reasons for some of the contradictions in the evidence are also discussed.

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Section: Types Of Cyclic Polymersmentioning

confidence: 99%

Crystallization of Cyclic Polymers

Pérez-Camargo

Múgica

Zubitur

et al. 2015

Polymer Crystallization I

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“…The molecular weight peaks were assigned to two major species consistent with that found in the literature; 38,41,42 the first, the azide end-group with its parent polymer ([X + Na] + ) and in-source expulsion of N 2 ([X -N 2 + Na] + and [X -N 2 + K] + ) 41 , and the second, an internal double bond found from fragmentation of the halide endgroup ([X-Br -HBr + Na] + ) 42 . The accuracy of the EGF determinations is subject to a large uncertainty due to the large signal to noise ratio found in the spectra and could underestimate the EGF.…”

Section: Resultssupporting

confidence: 82%

New insights into copper-mediated polymerization and polymer topologies

Gavrilov¹

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Polymer science has developed new synthetic methods to create complex polymer architectures. The solution and bulk properties of these architectures are influenced by the structure and chemical composition of the original building blocks (e.g. monomers or reactive polymeric blocks). One of the greatest challenges to the field is characterization of these polymers with diverse structures and chemical compositions. Size exclusion chromatography (SEC) has been one of the most used characterization techniques to determine the molecular weight distribution (MWD) of polymers. The information obtained about the polymer from SEC is generally restricted to molecular weight averages and dispersity indexes. However, there is a wealth of valuable information that can be obtained from a deeper analysis of the SEC chromatograms. This information can provide insights into polymerization mechanisms, the amount of unreacted polymer in a coupling reaction, or even the amount of cyclic polymer formed during a ring-closure reaction.The thesis first develops the theory to analyse the SEC chromatograms and provides a methodology to fit the MWDs with a log-normal distribution (LND) model based on a Gaussian function. The LND model was then used to analyse polymers made by a variant of copper-mediated ‗living' radical polymerization (LRP) in water. This LRP technique is capable of producing hydrophilic polymers with both narrow MWDs and high chain-end functionality, but the chain-end halide groups were susceptible to hydrolysis upon purification attempts and, therefore, the polymers cannot be further used to create complex polymer architectures. To preserve high chain-end functionality, the terminal halide of the polymers was capped using in situ azidation at the end of aqueous coppermediated LRP. The azide chain-end fidelity of the purified polymer was tested in a coppercatalyzed azide-alkyne cycloaddition (CuAAC) ‗click' reaction. The LND model of MWDs of the resulting products gave an accurate determination of the end-group functionality and insight into the effectiveness of our new polymerization variant.In the final stage of this thesis, the LND model was used to quantify the sequential polymerization of cyclic macromers through successive CuAAC ‗click' reactions. The versatility of the LND model was further demonstrated by determining the multicyclic coil conformation as a function of the number of cyclic macromers in the polymer chain.iii Declaration by authorThis thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have included in my thesis.I have clearly stated the contribution of others to my thesis as a whole, including statistical assistance, survey design, data analysis, significant technical procedures, professional editorial advice, and any other original research work used or reported in my thesis. The content of my ...

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“…Bis-methylsulfonyl PEG 9 shows near quantitative transformation with expected mass increase of 156.0 Da relative to its precursor, and subsequently, the bis-azido-PEG 10 exhibits a mass decrease of 106.1 Da. Additionally, metastable peaks are observed that correspond to the known loss of N 2 from each azide of the bis-azido-PEG 10 under MALDI conditions, (Li et al 2010b) providing further evidence for the presence of two azido end groups.…”

Section: Characterization Of Initially Functionalized Silicon Nanoparmentioning

confidence: 82%

Water-soluble PEGylated silicon nanoparticles and their assembly into swellable nanoparticle aggregates

Zhang

et al. 2015

J Nanopart Res

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Water-soluble silicon nanoparticles were synthesized by grafting PEG polymers onto functionalized silicon nanoparticles with distal alkyne or azide moieties. The surface-functionalized silicon nanoparticles were produced in one step from the reactive high-energy ball milling (RHEBM) of silicon wafers with a mixture of either 5-chloro-1-pentyne in 1-pentyne or 1,7 octadiyne in 1-hexyne to afford air and water-stable chloroalkyl or alkynyl-terminated nanoparticles, respectively. Nanoparticles with the xchloroalkyl substituents were easily converted to xazidoalkyl groups through the reaction of the Si nanoparticles with sodium azide in DMF. The azidoterminated nanoparticles were then grafted with mono-alkynyl-PEG polymers using a coppercatalyzed alkyne-azide cycloaddition (CuAAC) reaction to afford core-shell silicon nanoparticles with a covalently attached PEG shell. Covalently linked Si nanoparticle clusters were synthesized via the CuAAC ''click'' reaction of functional Si NPs with a,xfunctional PEG polymers of various lengths. Dynamic light scattering studies show that the flexible globular nanoparticle aggregates undergo a solvent-dependent change in volume (ethanol [ dichloromethane [ toluene) similar in behavior to hydrogel nanocomposites.

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MALDI−TOF Mass Spectral Characterization of Polymers Containing an Azide Group: Evidence of Metastable Ions

Cited by 80 publications

References 52 publications

Crystallization of Cyclic Polymers

Crystallization of Cyclic Polymers

New insights into copper-mediated polymerization and polymer topologies

Water-soluble PEGylated silicon nanoparticles and their assembly into swellable nanoparticle aggregates

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