2D-LC/SEC-(MALDI-TOF)-MS Characterization of Symmetric and Nonsymmetric Biocompatible PEOm–PIB–PEOn Block Copolymers

Automatic peak assignment and visualisation of copolymer mass spectrometry data using the 'genetic algorithm'

Copolymer analysis is vitally important as the materials have a wide variety of applications due to their tunable properties. Processing mass spectrometry data for copolymer samples can be very complex due to the increase in the number of species when the polymer chains are formed by two or more monomeric units. In this paper, we describe the use of the genetic algorithm for automated peak assignment of copolymers synthesised by a variety of polymerisation methods. We find that in using this method we are able to easily assign copolymer spectra in a few minutes and visualise them into heat maps. These heat maps allow us to look qualitatively at the distribution of the chains, by showing how they alter with different polymerisation techniques, and by changing the initial copolymer composition. This methodology is simple to use and requires little user input, which makes it well suited for use by less expert users. The data outputted by the automatic assignment may also allow for more complex data processing in the future.

Mass spectrometry as a tool to advance polymer science

In contrast to natural polymers, which have existed for billions of years, the first well-understood synthetic polymers date back to just over one century ago. Nevertheless, this relatively short period has seen vast progress in synthetic polymer chemistry, which can now afford diverse macromolecules with varying structural complexities. To keep pace with this synthetic progress, there have been commensurate developments in analytical chemistry, where mass spectrometry has emerged as the pre-eminent technique for polymer analysis. This Perspective describes present challenges associated with the mass-spectrometric analysis of synthetic polymers, in particular the desorption, ionization and structural interrogation of high-molar-mass macromolecules, as well as strategies to lower spectral complexity. We critically evaluate recent advances in technology in the context of these challenges and suggest how to push the field beyond its current limitations. In this context, the increasingly important role of high-resolution mass spectrometry is emphasized because of its unrivalled ability to describe unique species within polymer ensembles, rather than to report the average properties of the ensemble.

Synthesis and characterization of new photoswitchable azobenzene-containing poly(ε-caprolactones)

A novel and efficient strategy in obtaining mono- and bi-armed azobenzene-containing poly(ε-caprolactone)s is described, starting from a commercially available azobenzene dye.

Utilising alternative modifications of α-olefin end groups to synthesise amphiphilic block copolymers

Amphiphilic block copolymers comprised of polyisobutylene (PIB) and poly(2-(dimethylamino)ethyl methacrylate) (DMAEMA) have been synthesised.

A Novel Poly(ionic liquid) Interface-Free Two-Dimensional Monolithic Material for the Separation of Multiple Types of Glycoproteins

Currently, many types of affinity materials have been developed for the enrichment of glycoproteins potentially considered to be clinical biomarkers; however, they can not effectively distinguish between different glycoproteins and thus lack the functionality that may be the key to the diagnosis of specific diseases. In the present work, a novel interface-free 2D monolithic material has been developed for the separation of multiple types of glycoproteins, in which boronate-functionalized graphene acts as preconcentration segment and poly(guanidinium ionic liquid) acts as separation segment. The resultant 2D material was characterized by X-ray photoelectron spectroscopy, elemental analysis, and electroosmotic flow analysis to demonstrate successful modification at each step. The performance of this 2D material was evaluated by capillary electrochromatography and allowed the successful online concentration and separation of five standard glycoproteins. The high separation efficiency can be largely attributed to the good orthogonality of boronate-functionalized graphene monolith and poly(guanidinium ionic liquid) monolith.

Molecular arrangement of symmetric and non-symmetric triblock copolymers of poly(ethylene oxide) and poly(isobutylene) at the air/water interface

The behavior of a series of amphiphilic triblock copolymers of poly(ethylene oxide) (PEO) and poly(isobutylene) (PIB); including both symmetric (same degree of polymerization (DP) of the terminal PEO blocks) PEOm-b-PIBn-b-PEOm and non-symmetric (different DP of the terminal PEO blocks) PEOm-b-PIBn-b-PEOz, is investigated at the air/water interface by measuring surface pressure vs mean molecular area isotherms (π vs mmA), Langmuir-Blodgett (LB) technique, and infrared reflection-absorption spectroscopy (IRRAS). The block copolymer (PEO32-b-PIB160-b-PEO32) with longer PEO segments forms a stable monolayer and the isotherm reveals a pseudo-plateau starting at π∼5.7 mN/m, also observed in the IRRAS, which is assigned to the pancake-to-brush transition related to the PEO dissolution into the subphase and subsequent PEO brush dehydration. Another plateau is observed at π∼40 mN/m, which is attributed to the film collapse due to multilayer formation. The pancake-to-brush transition could not be observed for samples with smaller PEO chains. The isotherms for block copolymers, with short PEO chains, both symmetric (PEO3-b-PIBn-b-PEO3) and non-symmetric (PEO12-b-PIBn-b-PEO3), reveal another transition at π∼20-25 mN/m. This is interpreted to be due to the conformational transition from a folded state where the middle PIB block is anchored to the water surface at both ends by the terminal hydrophilic segments to an unfolded state with PIB anchored to the water surface at one end. It is assumed that this transition involves the removal of PEO3 chains from the water surface in case of non-symmetric PEO12-b-PIB85-b-PEO3 and in case of symmetric, probably one PEO3 of each PEO3-b-PIB85-b-PEO3 chain. Because of the weaker interaction of the short PEO3 chains with the water surface as compared with the relatively longer PEO12 chains, the film of PEO3-b-PIB85-b-PEO3 collapses at much lower surface pressure after the transition as compared with the PEO12-b-PIB85-b-PEO3. The AFM images reveal the formation of microdomains of almost uniform height (6-7 nm) in LB films of PEO3-b-PIB85-b-PEO3 and PEO12-b-PIB85-b-PEO3 after transferring onto silicon surfaces. These domains are assumed to be the mesomorphic domains of ordered and folded PIB chains.

Synthesis of an Amphiphilic β-Turn Mimetic Polymer Conjugate

A new biomimetic polymer containing a beta-turn mimetic element (1) was synthesized, using a combination of living carbocationic polymerization (LCCP), amidation, and "click" chemistry. Two different α-ω-functionalized polyisobutylenes (PIBs 3 and 5) bearing either an alkyne group (PIB 3) or a primary amine group (PIB 5) were directly synthesized via LCCP. The linking of the two PIB strands with the closely positioned carboxyl/azido moieties of a β-turn dipeptide (BTD) 2 was achieved via a sequence of amidation reaction and the Cu^I-mediated azide/alkyne "click" reaction. By means of size exclusion chromatography (SEC), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), NMR spectroscopy, and LC/MALDI-TOF MS, a detailed structural proof of the β-turn mimetic PIB conjugate (1) was possible.