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Hydrogels based on acylhydrazone end-linked Tetronic T904 four-armed amphiphilic star block copolymers show thermally-induced aqueous self-assembly and toughening, and cross-link dissociation and association traceable via simple 1H NMR spectroscopy.

Macrocyclic poly(glycidyl phenyl ether) (pGPE) synthesized via zwitterionic ring opening polymerization is typically contaminated by chains with linear and tadpole architecture. Although mass spectrometry (MS) analysis can readily confirm the presence of the linear byproduct, due to its unique mass, it is unable to differentiate between the cyclic and tadpole structures, which are constitutional isomers produced by backbiting reactions in monomeric or dimeric chains, respectively. To overcome this problem, ultraperformance reversed-phase liquid chromatography interfaced with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) was employed. The separation achieved by UPLC revealed that the tadpole isomer elutes before the cyclic structure because of the increased polarity afforded by its distinctive substituents. The ratio of tadpole to cyclic species increased with the degree of polymerization, in agreement with the synthetic method used, as the potential for forming tadpole structures by backbiting is entropically favored in longer polymer chains. Once separated, the two isomers could be independently characterized by tandem mass spectrometry. The macrocyclic and tadpole species exhibit unique fragmentation patterns, including structurally diagnostic fragments for each structure., Support from the National Science Foundation (CHE-1808115 to C. W.) is gratefully acknowledged.

The utilization of carbon dioxide as a polymer feedstock is an ongoing challenge. This report describes the catalytic conversion of carbon dioxide and an olefin comonomer, 1,3-butadiene, into a polymer structure that arises from divergent propagation mechanisms. Disubstituted unsaturated δ-valerolactone

We have successfully synthesized a series of monodispersed chain-like giant molecules with precisely controlled macromolecular composition and sequence based on polyhedral oligomeric silsesquioxane (POSS) nanoparticles using an orthogonal “click” strategy. Their nonspherical supramolecular structures, such as lamellae, double gyroids, and hexagonal packed cylinders, are mainly determined by the composition (namely, the number of incorporated amphiphilic nanoparticles). In addition, by precisely alternating the sequence of arranged nanoparticles in the giant molecules with identical chemical compositions, the domain sizes of their supramolecular structures could be fine-tuned. This is attributed to the macromolecular conformational differences caused by collective hydrogen bonding interactions in each set of sequence isomeric giant molecules. This work has demonstrated multilevel manipulation of supramolecular structures of giant molecules: coarse tuning by composition and fine-tuning by sequence.

The preference for a shorter chain component at a polymer blend surface impacts surface properties key to application-specific performance. While such segregation is known for blends containing low molecular weight additives or systems with large polydispersity, it has not been reported for anionically polymerized polymers that are viewed, in practice, as monodisperse. Observations with surface layer matrix-assisted laser desorption ionization time-of-flight mass spectrometry (SL-MALDI-ToF-MS), which distinguishes surface species without labeling and provides the entire molecular weight distribution, demonstrate that entropically driven surface enrichment of shorter chains occurs even in low polydispersity materials. For 6 kDa polystyrene the number-average molecular weight (Mn) at the surface is ca. 300 Da (5%) lower than that in the bulk, and for 7 kDa poly(methyl methacryalate) the shift is ca. 500 Da. These observations are in qualitative agreement with results from a mean-field theory that considers ...

A series of shape amphiphiles based on functionalized polyhedral oligomeric silsesquioxane (POSS) head tethered with two polymeric tails of symmetric or asymmetric compositions was designed and synthesized using sequential "grafting-from" and "click" surface functionalization. The monofunctionalization of octavinylPOSS was performed using thiol-ene chemistry to afford a dihydroxyl-functionalized POSS that was further derived into precisely defined homo- and heterobifunctional macroinitiators. Polymer tails, such as polycaprolactone and polystyrene, could then be grown from these POSS-based macroinitiators with controlled molecular weight via ring-opening polymerization and atom transfer radical polymerization (ATRP). The vinyl groups on POSS were found to be compatible with ATRP conditions. These macromolecular precursors were further modified by thiol-ene chemistry to install surface functionalities onto the POSS cage. The polymer chain composition and POSS surface chemistry can thus be tuned separately in a modular and efficient way.

Surface layer matrix-assisted laser desorption ionization time-of-flight mass spectrometry (SL-MALDI-TOF MS) is a powerful new surface sensitive technique to quantify the surface concentration of multicomponent polymer films with enrichment of one component at the surface. Its capabilities are demonstrated for the novel case of a blend of cyclic polystyrene with linear polystyrene, in which we find the composition of linear chains enriched at the surface after annealing, contrary to the expectation of a self-consistent field theory. The probing depth was confirmed to be monomolecular, which for these short chains is less than 2 nm, even though material at a much greater depth is removed by the analysis.

Head diversification of shape amphiphiles not only broadens the scope of supramolecular engineering for new self-organizing materials but also facilitates their potential applications in high technologies. In this letter, T

Rapid and precise synthesis of macromolecules has been a grand challenge in polymer chemistry. In this letter, we describe a convenient, rapid, and robust strategy for a one-pot synthesis of various precisely defined giant surfactants based on polyhedral oligomeric silsesquioxane (POSS). The method combines orthogonal oxime ligation, strain-promoted azide–alkyne cycloaddition (SPAAC), and thiol–ene “click” coupling. The process is usually completed within 0.5–2 h and does not require chromatography methods for purification. With near quantitative conversion efficiency, the method yields giant surfactants with distinct topologies, including single-tailed and asymmetric, multitailed giant surfactants. Both polymer tail composition and POSS surface chemistry are controlled precisely and tuned independently, enabling the design and preparation of new classes of giant surfactants.

Engine oil is mainly comprised of base oils and various additives, which are low molecular weight polymers mixed into the oil resulting in a polymer blend. Dispersants and detergents, the two most ...

EIIR, a derivative of isobutylene-isoprene rubber (IIR) with geminal vinylidene-acrylate motifs, has been synthesized by grafting ethyl propiolate to IIR via EtAlCl2-catalyzed Alder-ene reaction. M...

Controlled assembly of nanoscale building blocks is a promising approach to obtain functional materials with unique properties. Here, we report a way to manipulate the supramolecular structures of ...

Poly-L-lysine (PLL), polystyrenesulfonate (PSS), and a mixture of these polyelectrolytes were investigated by electrospray ionization ion mobility mass spectrometry. The IM step confirmed the formation of noncovalent (i.e., supramolecular) complexes between these polyelectrolytes, which were detected in various charge states and stoichiometries in the presence of their constituents. Experimental and theoretical collision cross sections (CCSs) were derived for both PLL and PSS oligomers as well as their noncovalent assemblies. PSS chains showed higher compactness with increasing size as compared to PLL chains, indicating that the intrinsic conformations of the polyelectrolytes depend on the nature of the functional groups on their side chains. The CCS data for the noncovalent complexes further revealed that assemblies with higher PLL content have higher CCS values than other compositions of similar mass and that PLL PSS complex formation is accompanied by significant size contraction.

This research paper describes a general method to synthesize functional polymers using a combination of atom transfer radical polymerization and hydrosilation. Methyl methacrylate (MMA) was copolymerized with (4-vinylphenyl)dimethylsilane (VPDS) in toluene via atom transfer radical polymerization (ATRP). The presence of a silyl hydride bond was proven using MALDI-ToF, NMR and IR spectra. The ability of the copolymer to undergo hydrosilation reaction was confirmed by reacting it with allyl alcohol. The expected molecular weight increase of the final polymer after functionalization was in agreement with the observed molecular weight. This method can be used to control both the type and quantity of functionalization by varying the amount of VPDS in the monomer feed.

Ultraperformance liquid chromatography (UPLC) and ion mobility (IM) spectrometry were interfaced with mass spectrometry (MS) and tandem mass spectrometry (MS/MS) to characterize a complex nonionic surfactant mixture. The surfactant was composed of a glycerol core, functionalized with poly(ethylene oxide) units (PEOn) that were partially esterified by caprylic and/or capric acid. Reversed-phase UPLC classified the blend based on polarity into four groups of eluates, corresponding to compounds with zero, one, two, or three fatty acid residues. Additional separation within each eluate group was achieved according to the length of the fatty acid chains. Coeluting molecules of similar polarity were dispersed in the gas phase by their collision cross section in the IM dimension. Performed in series, UPLC and IM allowed for the separation and detection of several isomeric and isobaric blend constituents, thereby enabling their isolation for conclusive MS/MS analysis to confirm or elucidate their primary structures and architectures (overall four-dimensional, 4D, characterization).

Tandem mass spectrometry (MS2) has been employed to elucidate the topology and branching architecture of star-branched polyethers. The polymers were ionized by matrix-assisted laser desorption/ionization (MALDI) to positive ions and dissociated after leaving the ion source via laser-induced fragmentation. The bond scissions caused under MALDI-MS2 conditions occur preferentially near the core-branch joining points due to energetically favorable homolytic and heterolytic bond cleavages near the core and release of steric strain and/or reduction of crowding. This unique fragmentation mode detaches complete arms from the core generating fragment ion series at the expected molecular weight of each branch. The number of fragment ion distributions observed combined with their mass-to-charge ratios permit conclusive determination of the degree of branching and the corresponding branch lengths, as demonstrated for differently branched homo- and mikto-arm polyether stars synthesized via azide-alkyne click chemistry. The results of this study underscore the utility of MS2 for the characterization of branching architecture and branch lengths of (co) polymers with two or more linear chains attached to a functionalized central core.

Three bimetallic triangles were constructed via a step-wise assembly of tailored terpyridine building blocks. Oligomeric trimer 2 was obtained by reacting ligand 1 with Ru(II). Subsequent cyclization of trimer 2 with Zn(II), Cd(II), and Fe(II) resulted in the formation of bimetallic triangles 3, 4, and 5 in high yield, respectively. All triangles were characterized by NMR spectroscopy, ESI and travelling-wave ion mobility-mass spectrometry (MS), as well as gradient MS, which provided insight into their stabilities.

In this work, we studied the linker effect on the nanostructures of a serious of specifically designed, functionalized polyhedral oligomeric silsesquioxane (POSS) based Dendron-like macro-isomers. The varying linkers between hydrophilic and hydrophobic POSS cages lead to topological isomers with identical composition but different molecular shapes. Their unique phase behaviors highlight remarkable effects of molecular architectures on the formation of nanostructures. Due to topological constraints, these macro-isomers assume either a fan- or a cone-molecular shape, which assembles into either hexagonally packed cylindrical phase (HEX) or Frank-Kasper A15 phase. This work provides guiding rules on designing precise molecular nanostructures with desired properties via linker engineering.

Thermal desorption/degradation with an atmospheric solids analysis probe (ASAP) and ion mobility (IM) separation are coupled with mass spectrometry (MS) analysis and tandem mass spectrometry (MS/MS) fragmentation to characterize thermoplastic elastomers. The compounds investigated, which are used in the manufacture of a wide variety of packaging materials, are mainly composed of thermoplastic copolymers, but also contain additional chemicals ("additives"), like antioxidants and UV stabilizers, for enhancement of their properties or protection from degradation. The traditional method for analyzing such complex mixtures is vacuum pyrolysis followed by electron or chemical ionization mass spectrometry, often after gas chromatography separation. Here, an alternative, faster approach, involving mild degradation at atmospheric pressure (ASAP) and subsequent characterization of the desorbates and pyrolyzates by IM-MS, and if needed, MS/MS is presented. Such multidimensional dispersion considerably simplifies the resulting spectra, permitting the conclusive separation, characterization, and classification of the multicomponent materials examined.

Three sets of polyoxometalate (POM)-based amphiphilic hybrid macromolecules with different rigidity in their organic tails are used as models to understand the effect of molecular rigidity on their possible self-recognition feature during self-assembly processes. Self-recognition is achieved in the mixed solution of two structurally similar, sphere-rigid T-shape-linked oligofluorene(TOF

Nonenzymatic RNA polymerization, a major challenge in understanding the origins of life on early Earth, was previously achieved in the presence of montmorillonite clay and high magnesium concentrat...

An efficient method for synthesis of well-defined, well-characterized, tadpole-shaped polystyrene with a single atom junction point that is optimal for the study of dynamics has been developed using anionic polymerization, silicon chloride linking chemistry, and metathesis ring closure. The difunctional macromolecular linking agent, ω-methyldichlorosilylpolystyrene, was formed by reacting sec-butyllithium-initiated poly(styryl)lithium with excess (30×) methyltrichlorosilane to eliminate formation of linear dimer and three-arm star polystyrene. The asymmetric, three-arm, star precursor was formed by linking excess α-4-pentenylpoly(styryl)lithium (α-PSLi) with the macromolecular linking agent, and the excess α-PSLi functionalized with ethylene oxide before termination with methanol to facilitate chromatographic separation. Cyclization of the three-arm, star precursor to form tadpole-shaped polystyrene was effected in methylene chloride at high dilution using the Grubbs first generation catalyst, bis(tricycl...

Planar, terpyridine-based metal complexes with the Sierpinski triangular motif and alkylated corners undergo a second self-assembly event to give megastructural Sierpinski pyramids; assembly is driven by the facile lipophilic-lipophilic association of the alkyl moieties and complementary perfect fit of the triangular building blocks. Confirmation of the 3D, pyramidal structures was verified and supported by a combination of TEM, AFM, and multiscale simulation techniques.

Thermotropic order-order phase transitions (OOTs) in block copolymers are not commonly observed in the strong segregation region. Phase separation of giant surfactants composed of hydrophilic molecular nanoparticles (MNPs) as heads and hydrophobic flexible polymer chains as tails occurs generally in the strong segregation region. By introducing a rigid molecular segment at the junction point of the giant surfactants, the interface between the MNPs and polymer tails could be delicately manipulated, resulting in the occurrence of thermotropic OOTs that are sensitively dependent on the properties of those junction segments. For samples with hydrophilic junction segments, no thermal-induced OOT has been observed. However, for samples with hydrophobic junction segments, complicated thermotropic OOTs between as many as four different ordered phases in a single giant surfactant system, from lamellae (LAM) to hexagonally perforated layer structure (HPL), double gyroids (DG), and finally to hexagonally packed cylinders (HEX), have been observed with increasing temperature. These results demonstrated that interfacial engineering could be used to regulate the self-assemble behavior of macromolecules at the nanometer scales.

We observe the formation of highly controllable and responsive onion-like vesicles by using rigid sphere-rod amphiphilic hybrid macromolecules, composed of charged, hydrophilic Keggin-type clusters (spheres) and hydrophobic rod-like oligofluorenes (OFs). Unlike the commonly used approach, which mainly relies on chain bending of flexible molecules to satisfy different curvatures in onion-like vesicles, the rigid hybrids form flexible interdigitations by tuning the angles between OFs, leading to the formation of bilayers with different sizes. The self-assembled vesicles possess complete onion-like structures from most inner to outer layers, and their size (layer number) can be accurately manipulated by different solution conditions including solvent polarity, ionic strength, temperature, and hybrid concentration, with fixed interbilayer distance under all conditions. Moreover, the vesicle size (layer number) shows excellent reversibility to the change of temperature. The charged feature of spheres, rod length, and overall hybrid architecture shows significant effects on the formation of such onion-like vesicles.

HBT-Cy 1 has been previously reported as a highly selective fluorescent probe for lysosome visualization in live cells. To further investigate the role of the structural components of HBT-Cy in lysosome selectivity, cyanine based fluorescent probe series (2–5) have been synthesized in good yields by connecting benzothiazolium cyanine (Cy) with 2-hydroxyphenylbenzothiazole (HBT) via a meta phenylene ring. Probes 2–5 exhibited exceptional photophysical properties including bright red-emission (λem ≈ 630–650 nm), a large Stokes shift (Δλ > 130 nm) and high fluorescence quantum yields (ϕfl ≈ 0.1–0.5). Probes 2, 3, and 5 exhibited exceptional selectivity towards cellular lysosomes in NHLF and MO3.13 cells. Our further study revealed that the phenyl benzothiazolium cyanine component (6) was the lysosome directing group in the HBT-Cy probe structure. The attachment of the hydroxyphenyl benzothiazole (HBT) component to the HBT-Cy probe structure has significantly improved its photophysical properties. Lysosome probes 2, 3 and 5 exhibited excellent biocompatibility, quick staining, bright red fluorescence, and wash-free application for live cell imaging. These probes further exhibited excellent characteristics for bioimaging experiments including a non-alkalinizing nature, high biocompatibility, high photostability and long-term imaging ability (>4 hours).

The surface of a blend of 6 kDa polystyrene and 6 kDa polystyrene functionalized with hydroxymethyl ends not only is depleted of the higher energy end groups but also is depleted of any segments belonging to the functionalized chains. This is demonstrated using the emerging technique of surface layer matrix-assisted laser desorption ionization time-of-flight mass spectrometry (SL-MALDI-ToF-MS), which detects entire chains that have any repeat unit at the outer surface, and requires no labeling. Detecting entire chains provides information about the relationship of chain functionalization to surface segregation behavior of entire chains. That the surface is depleted of interior segments of functionalized chains as well as of the ends is remarkable, since the functionality at the single chain end involves less than 0.5 wt % of the functionalized polymer chain.

Tandem mass spectrometry (MS2) via collisionally activated dissociation (CAD), coupled with ion mobility (IM) separation, has been employed to determine the sequence of macrocyclic polyester copolymers with thermoresponsive properties. The polyesters were synthesized by polyesterification of succinic acid with two diols functionalized with different, bioinspired amide pendants. MS analysis confirmed the formation of cyclic and linear chains composed of two different polyester repeat units, N and P. MS2 experiments on the sodiated macrocyclic trimer P3 showed that fragmentation encompasses ring opening by 1,5-H rearrangement over an ester group and consecutive dissociation of the ring-opened species via the same mechanism. Investigation of the macrocyclic trimers N1P2 and N2P3 revealed that ring opening occurs randomly at any of the ester groups of the macrocycle. Armed with these data, the sequence of the macrocyclic tetramer N2P2 was elucidated based on the dimeric NN, NP (or PN), and PP fragments generated by CAD of the sodiated ion. The observed fragment distribution provided evidence that the tetramer had predominantly a block architecture, viz. cyclo-NNPP. Preference for the block arrangement of the monomers was also found for a linear oligomer with four diol units. The IM dimension enabled the examination of singly sodiated cyclic or linear chains that overlapped with higher charge states of larger oligomers. The described sequencing strategy should be generally applicable to polymers with ester groups in the backbone. The architectural information deduced by such sequencing would significantly facilitate structure/property correlations and the design of copolymers with the desired physical properties.

Incorporating the building blocks of nature (e.g., peptides and DNA) into inorganic polyoxometalate (POM) clusters is a promising approach to improve the compatibilities of POMs in biological fields. To extend their biological applications, it is necessary to understand the importance of different non-covalent interactions during self-organization. A series of Anderson POM-peptide hybrids have been used as a simple model to demonstrate the role of different interactions in POM-peptide (biomolecules) systems. Regardless of peptide chain length, these hybrids follow similar solution behaviors, forming hollow, spherical supramolecular structures in acetonitrile/water mixed solvents. The incorporation of peptide tails introduces interesting stimuli-responsive properties to temperature, hybrid concentration, solvent polarity and ionic strength. Unlike the typical bilayer amphiphilic vesicles, they are found to follow the blackberry-type assemblies of hydrophilic macroions, which are regulated by electrostatic interaction and hydrogen bonding. The formation of electrostatic assemblies before the supramolecular formation is confirmed by ion-mobility mass spectrometry (IMS-MS).

Conjugation of poly(ethylene glycol) (PEG) to protein drugs (PEGylation) is increasingly utilized in the biotherapeutics field because it improves significantly the drugs' circulatory half-life, solubility, and shelf-life. The activity of a PEGylated drug depends on the number, size, and location of the attached PEG chain(s). This study introduces a 2D separation approach, including reversed-phase ultra-performance liquid chromatography (RP-UPLC) and ion mobility mass spectrometry (IM-MS), in order to determine the structural properties of the conjugates, as demonstrated for a PEGylated insulin sample that was prepared by random amine PEGylation. The UPLC dimension allowed separation based on polarity. Electrospray ionization (ESI) of the eluates followed by in-source dissociation (ISD) truncated the PEG chains and created insulin fragments that provided site-specific information based on whether they contained a marker at the potential conjugation sites. Separation of the latter fragments by size and charge in the orthogonal IM dimension (pseudo-4D UPLC-ISD-IM-MS approach) enabled clear detection and identification of the positional isomers formed upon PEGylation. The results showed a highly heterogeneous mixture of singly and multiply conjugated isomers plus unconjugated material. PEGylation was observed on all three possible attachment sites (e-NH2 of LysB29, A- and B-chain N-termini). Each PEGylation site was validated by analysis of the same product after disulfide bond cleavage, so that the PEGylated A- and B- chain could be individually characterized with the same pseudo-4D UPLC-ISD-IM-MS method.

The sequence and helical content of two alanine-rich peptides (AQK18 and GpAQK18, Gp: l-propargylglycine) and their conjugates with poly(ethylene glycol) (PEG) have been investigated by multidimensional mass spectrometry (MS), encompassing electrospray ionization (ESI) or matrix-assisted laser desorption ionization (MALDI) interfaced with tandem mass spectrometry (MS2) fragmentation and shape-sensitive separation via ion mobility mass spectrometry (IM-MS). The composition, sequence, and molecular weight distribution of the peptides and bioconjugates were identified by MS and MS2 experiments, which also confirmed the attachment of PEG at the C-terminus of the peptides. ESI coupled with IM-MS revealed the existence of random coil and α-helical conformers for the peptides in the gas phase. More importantly, the proportion of the helical conformation increased substantially after PEG attachment, suggesting that conjugation adds stability to this conformer. The conformational assemblies detected in the gas pha...

The quantitative, single step, self-assembly of a shape-persistent, three-dimensional C3v-symmetric, triptycene-based tris-terpyridinyl ligand initially gives a platonic-based cubic architecture, which was unequivocally characterized by 1D and 2D NMR spectroscopy, mass spectrometry, and single crystal X-ray structural analysis. The unique metal-ligand binding properties of the Cd2+ analogue of this construct give rise to a concentration-dependent dynamic equilibrium between cube, prism, and tetrahedron-shaped architectures. Dilution transforms this cube into two identical tetrahedra through a stable prism-shaped intermediate; increasing the concentration reverses the process.

Spontaneous organizations of designed elements with explicit shape and symmetry are essential for developing useful structures and materials. We report the topologically directed assemblies of four categories (a total of 24) of sphere–rod conjugates, composed of a sphere-like fullerene (C60) derivative and a rod-like oligofluorene(s) (OF), both of which are promising organic semiconductor materials. Although the packing of either spheres or rods has been well-studied, conjugates having both shapes substantially enrich resultant assembled structures. Mandated by their shapes and topologies, directed assemblies of these conjugates result not only in diverse unconventional semiconducting supramolecular lattices with controlled domain sizes but also in tunable charge transport properties of the resulting structures. These results demonstrate the importance of persistent molecular topology on hierarchically assembled structures and their final properties.

Although controlling the primary structure of synthetic polymers is itself a great challenge, the potential of sequence control for tailoring hierarchical structures remains to be exploited, especially in the creation of new and unconventional phases. A series of model amphiphilic chain-like giant molecules was designed and synthesized by interconnecting both hydrophobic and hydrophilic molecular nanoparticles in precisely defined sequence and composition to investigate their sequence-dependent phase structures. Not only compositional variation changed the self-assembled supramolecular phases, but also specific sequences induce unconventional phase formation, including Frank-Kasper phases. The formation mechanism was attributed to the conformational change driven by the collective hydrogen bonding and the sequence-mandated topology of the molecules. These results show that sequence control in synthetic polymers can have a dramatic impact on polymer properties and self-assembly.

A methodology to efficiently synthesize well-defined, 8-shaped polystyrene using anionic polymerization, silicon chloride linking chemistry, and metathesis ring closure has been developed, and the 8-shaped architecture was ascertained using the fragmentation pattern of the corresponding Ag+ adduct, acquired with tandem mass spectrometry. The 4-arm star precursor, 4-star-α-4-pentenylpolystyrene, was formed by linking α-4-pentenylpoly(styryl)lithium (PSLi) with 1,2-bis(methyldichlorosilyl)ethane and reacting the excess PSLi with 1,2-epoxybutane to facilitate purification. Ring closure of 4-star-α-4-pentenylpolystyrene was carried out in dichloromethane under mild conditions using a Grubbs metathesis catalyst, bis(tricyclohexylphosphine)benzylidine ruthenium(IV) chloride. Both the 4-arm star precursor and resulting 8-shaped polystyrene were characterized using SEC, NMR, and MALDI-ToF mass spectrometry (MS). Tandem mass spectrometry (MS2) was used for the first time to study the fragmentation pattern of 8-sha...

The biodegradable polyester copolymer poly(propylene fumarate) (PPF) is increasingly utilized in bone tissue engineering studies due to its suitability as inert cross-linkable scaffold material. The well-defined poly(propylene fumarate) oligomers needed for this purpose are synthesized by post-polymerization isomerization of poly(propylene maleate), which is prepared by ring opening polymerization of maleic anhydride and propylene oxide. In this study, multidimensional mass spectrometry methodologies, interfacing matrix-assisted laser desorption ionization and electrospray ionization with mass analysis, tandem mass spectrometry fragmentation and/or ion mobility mass spectrometry, have been employed to characterize the composition, end groups, chain connectivity and isomeric purity of the isomeric copolyesters poly(propylene maleate)and poly(propylene fumarate). It is demonstrated that the polymerization catalyst is incorporated into the polymer chain (as the initiating chain end) and that the poly(propylene maleate) to poly(propylene fumarate) isomerization using an amine base proceeds with quantitative yield. Hydrolytic degradation is shown not to alter the double bond geometry of the poly(propylene fumarate) or poly(propylene maleate) chains.