AB2 Monomer Research Articles

Synthesis of Aldehyde‐Functionalized Fluorescent Micelles by Self‐Assembly of a Hybrid Polymer Constructed by Hyperbranched Conjugated Polymer Core with Aldehyde End groups and Polyethylene Glycol Shell

AbstractWater‐dispersible fluorescent nano‐/microspheres have been widely used as fluorescent probes in many fields. In this paper, aldehyde‐functionalized fluorescent micelles are synthesized by self‐assembly of end‐modified hyperbranched poly(m‐phenyleneethynylene‐alter‐p‐phenyleneethynylene)(hb‐PMPE). First, hb‐PMPE with ‐Br end‐groups(hb‐PMPE‐Br) is obtained by the polymerization of AB2 monomer PhBr2–C≡C–Ph–C≡CH, then the reaction of hb‐PMPE‐Br with 4‐ethynylbenzaldehyde (EBA) gives end aldehyde‐functionalized hyperbranched polymer hb‐PMPE‐CHO. Hence, hb‐PMPE‐CHO is reacted with aminooxy methoxypolyethylene glycol‐2000 (NH2O‐MPEG2000) to link poly(ethylene glycol) (PEG) chains to the ends of hb‐PMPE‐CHO with partial residual aldehyde end‐groups, resulting in aldehyde‐functionalized amphiphilic polymer hb‐PMPE‐PEG. Fluorescent micelles with aldehyde‐containing fluorescent hb‐PMPE core and PEG shell are obtained by self‐assembling hb‐PMPE‐PEG in water. The micelle diameter is determined by the PEG content in hb‐PMPE‐PEG, which can be controlled by the reaction weight ratio of NH2O‐MPEG2000/hb‐PMPE‐CHO. When the ratio of NH2O‐MPEG2000/hb‐PMPE‐CHO > 0.75/1, micelles with a diameter < 50 nm are obtained. The water dispersion of hb‐PMPE‐PEG‐1/2 micelles (28.9 nm) emits bright green fluorescence with λmax ≈ 490 nm under UV irradiation, and the emission intensity increases with increasing concentration.

A unified kinetic analysis for the hyperbranched polymerization with ABg type monomers

The unified analytical expressions of the size distribution function and the degree of branching for the hyperbranched polymerization with ABg type monomers are developed by kinetic theory of polymerization, based on the ABg + ABh + Bf model. The effect of the reactant parameters, the monomers branching degree g and h, the monomers feed ratio r, the functionality f and feed ratio α of the core molecule Bf, on the molecular parameters of the products formed was investigated. Compared with the general polycondensation of ABg monomer or copolycondensation of ABg and AB monomer without core molecule, the presence of multifunctional core molecules makes the polydispersity index of the products go down fast when the reaction approaches completion. At the end of the reaction, the polydispersity index increases with increasing g, and decreases with increasing α and f. For the ABg + AB + B3 polycondensation system, within the range of the feed ratio of ABg monomer less than 0.3, the average chain segment length significantly decreases with the increasing r, and then the change becomes moderate with its further increase. For g > 2, the average chain segment length shows a shallow minimum with increasing r. The degree of branching, fractions of terminal and branching units also show maximum value with the change of monomer feed ratio r. The information obtained in this work can help people understand the structure of ABg type hyperbranched polymers and carry out molecular design.

Synthesis of Nano-Structured Conjugated Polymers with Multiple Micro-/Meso-Pores by the Post-Crosslinking of End-Functionalized Hyperbranched Conjugated Polymers.

A nano-structured conjugated polymer with multiple micro-/meso-pores was synthesized by post-crosslinking of an end-functionalized hyperbranched conjugated prepolymer. Firstly, an AB2 monomer 3-((3,5-dibromo-4-(octyloxy)phenyl)ethynyl)-6-ethynyl-9-octyl-9H-carbazole (PECz) was synthesized and polymerized by Sonogashira reaction to give the -Br end-functionalized hyperbranched conjugated prepolymer hb-PPECz. The photophysical and electrochemical properties of hb-PPECz were investigated. The λmax of absorption and emission of hb-PPECz in tetrahydrofuran (THF) solution was 313 and 483 nm, respectively. The optical energy bandgap, highest occupied molecular orbital (HOMO), and lowest unoccupied molecular orbital (LUMO) energy levels of hb-PPECz were 2.98, -5.81, and -2.83 eV, respectively. Then, the prepolymer hb-PPECz was post-crosslinked by Heck reaction with divinylbenzene to give the porous conjugated polymer c-PPECz. The effects of hb-PPECz concentration and added dispersant polyvinylpyrrolidone (PVP K-30) on the morphology and porosity of c-PPECz were investigated. The resulting c-PPECzs showed multiple porous structures mainly constructed by micropores and mesopores. Under a higher hb-PPECz concentration (4 wt/v%), a bulky gel product was obtained. Under lower hb-PPECz concentrations (0.6 wt/v%~2 wt/v%), the resulting c-PPECzs were mainly composed of nano-sized particles. Nearly spheric nanoparticles (200~300 nm) (c-PPECz-5) were obtained under the concentration of 1 wt/v% in the presence of PVP (10 wt% of hb-PPECz). The Brunauer-Emmett-Teller (BET) surface area, pore volume, average pore size, and percentage of pore size below 10 nm of c-PPECz-5 were 10.7781 m2·g-1, 0.0108 cm3·g-1, 4.0081 nm, and 94.47%, respectively.

Synthesis Landscapes for Ammonia Borane Chemical Vapor Deposition of h-BN and BNNT: Unraveling Reactions and Intermediates from First-Principles.

Planar hexagonal boron nitride (h-BN) and tubular BN nanotube (BNNT), known for their superior mechanical and thermal properties, as well as wide electronic band gap, hold great potential for nanoelectronic and optoelectronic devices. Chemical vapor deposition has demonstrated the best way to scalable synthesis of high-quality BN nanomaterials. Yet, the atomistic understanding of reactions from precursors to product-material remains elusive, posing challenges for experimental design. Here, performing first-principles calculations and ab initio molecular simulations, we explore pyrolytic decomposition pathways of the most used precursor ammonia borane (H3BNH3, AB) to BN, in gas-phase and on Ni(111) or amorphous boron (for BNNT growth) surfaces, for comparison. It reveals that in the gas phase, a pair of AB molecules cooperate to form intermediate NH3 and ammonia diborane, which further dissociates into H2BNH2, accompanied by critical BH4- and NH4+ ions. These ions act as H scavengers facilitating H2BNH2 dehydrogenation into HBNH. The consequent HBNH directly feeds BN flake growth by reacting with the crystal edge, while the addition of H2BNH2 to the edge is prohibited at 1500 K. In contrast, on Ni and boron surfaces, AB monomer dehydrogenates stepwise, deeper, yielding BNH and BN dimer as the primary building unit. Our study maps out three typical experimental conditions regarding the dissociation of AB-precursor, providing insights into the underlying reaction mechanisms of gas-phase precursors, to help as guidelines for the experimental growth of BN nanomaterials.

A Theoretical Investigation of the Polyaddition of an AB2+A2+B4 Monomer Mixture.

Hyperbranched polymers (HBPs) are widely applied nowadays as functional materials for biomedicine needs, nonlinear optics, organic semiconductors, etc. One of the effective and promising ways to synthesize HBPs is a polyaddition of AB2+A2+B4 monomers that is generated in the A2+CB2, AA'+B3, A2+B'B2, and A2+C2+B3 systems or using other approaches. It is clear that all the foundational features of HBPs that are manufactured by a polyaddition reaction are defined by the component composition of the monomer mixture. For this reason, we have designed a structural kinetic model of AB2+A2+B4 monomer mixture polyaddition which makes it possible to predict the impact of the monomer mixture's composition on the molecular weight characteristics of hyperbranched polymers (number average (DPn) and weight average (DPw) degree of polymerization), as well as the degree of branching (DB) and gel point (pg). The suggested model also considers the possibility of a positive or negative substitution effect during polyaddition. The change in the macromolecule parameters of HBPs formed by polyaddition of AB2+A2+B4 monomers is described as an infinite system of kinetic equations. The solution for the equation system was found using the method of generating functions. The impact of both the component's composition and the substitution effect during the polyaddition of AB2+A2+B4 monomers on structural and molecular weight HBP characteristics was investigated. The suggested model is fairly versatile; it makes it possible to describe every possible case of polyaddition with various monomer combinations, such as A2+AB2, AB2+B4, AB2, or A2+B4. The influence of each monomer type on the main characteristics of hyperbranched polymers that are obtained by the polyaddition of AB2+A2+B4 monomers has been investigated. Based on the results obtained, an empirical formula was proposed to estimate the pg = pA during the polyaddition of an AB2+A2+B4 monomer mixture: pg = pA = (-0.53([B]0/[A]0)1/2 + 0.78)υAB2 + (1/3)1/2([B]0/[A]0)1/2, where (1/3)1/2([B]0/[A]0)1/2 is the Flory equation for the A2+B4 polyaddition, [A]0 and [B]0 are the A and B group concentration from A2 and B4, respectively, and υAB2 is the mole fraction of the AB2 monomer in the mixture. The equation obtained allows us to accurately predict the pg value, with an AB2 monomer content of up to 80%.

Synthesis of triphenylamine-based nanoporous organic polymers for highly efficient capture of SO2 and CO2

Two triphenylamine-based nanoporous organic polymers were synthesized through the self-condensation of AB2 monomers. These polymers exhibit promising potential for capturing toxic gases and contaminants due to their highly effective uptake of SO2.

Synthesis of AB2 type hyperbranched polymer by CuAAC based 1,3-dipolar cycloaddition and its application in delivering curcumin to cancer cell cultures in-vitro

Hyperbranched polymers are three-dimensional macromolecules with unique physical and chemical properties, such as high solubility, low viscosity, and many functional groups at the terminals, as well as possible applications in several fields. Herein, we report the synthesis of a trifunctional AB2 monomer in a three-step process followed by "Click" polymerization via copper-catalyzed azide-alkyne cycloaddition to prepare a polytriazole-based hyperbranched polymer. Synthesized monomer and polymer were subsequently characterized by 1H and 13C NMR spectroscopy, and size-exclusion chromatography. The AB2 type hyperbranched polymer was self-assembled into lipid-polymer hybrid nanoparticles (HBP-NPs) through a nanoprecipitation approach, and curcumin (CUR) was incorporated into the HBP-NPs. The CUR-loaded HBP-NPs were characterized by particle size analysis, zeta potential, polydispersity index, morphology, drug entrapment efficiency, in vitro drug release, cellular uptake, and anticancer potential against HepG2 and NCI-H460 cell lines. The results indicated the CUR-loaded HBP-NPs demonstrated enhanced cell inhibition due to the improved delivery of CUR upon incorporation into HBP-NPs.

Polylactic-Containing Hyperbranched Polymers through the CuAAC Polymerization of Aromatic AB2 Monomers.

We report on the synthesis and characterization of a novel class of hyperbranched polymers, in which a copper(I)-catalyzed alkyne azide cycloaddition (CuAAC) reaction (the prototypical "click" reaction) is used as the polymerization step. The AB2 monomers bear two azide functionalities and one alkyne functionality, which have been installed onto a 1,3,5 trisubstituted benzene aromatic skeleton. This synthesis has been optimized in terms of its purification strategies, with an eye on its scalability for the potential industrial applications of hyperbranched polymers as viscosity modifiers. By taking advantage of the modularity of the synthesis, we have been able to install short polylactic acid fragments as the spacing units between the complementary reactive azide and alkyne functionalities, aiming to introduce elements of biodegradability into the final products. The hyperbranched polymers have been obtained with good molecular weights and degrees of polymerization and branching, testifying to the effectiveness of the synthetic design. Simple experiments on glass surfaces have highlighted the possibility of conducting the polymerizations and the formation of the hyperbranched polymers directly in thin films at room temperature.

Synthesis of Degradable Polysulfamides via Sulfur(VI) Fluoride Exchange Click Polymerization of AB-Type Monomers.

Polysulfamides are the -SO2- analogues of polyureas and form an intriguing family of polymers containing hydrogen-bond donor and acceptor groups. However, unlike polyureas, their physical properties are mostly unknown because of the scarcity of synthetic methods to access such polymers. Herein, we report an expedient synthesis of AB monomers for the synthesis of polysulfamides via Sulfur(VI) Fluoride Exchange (SuFEx) click polymerization. Upon optimization of the step-growth process, a variety of polysulfamides were isolated and characterized. The versatility of the SuFEx polymerization allowed structural modulation of the main chain through the incorporation of aliphatic or aromatic amines. While all synthesized polymers presented high thermal stability via thermogravimetric analysis, the glass-transition temperature and crystallinity were shown to be highly tied to the structure of the backbone between repeating sulfamide units through differential scanning calorimetry and powder X-ray diffraction. Careful analysis via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and X-ray crystallography also revealed the formation of macrocyclic oligomers during the polymerization of one AB monomer. Finally, two protocols were developed to efficiently degrade all synthesized polysulfamides through either chemical recycling for polymers derived from aromatic amines or oxidative upcycling for those based on aliphatic amines.

Eco-friendly synthesis of cardanol-based AB monomer for formaldehyde-free phenolic thermosets

Oxidative cleavage of cardanol to a single-component AB monomer allows the preparation of bio-based formaldehyde-free phenolic resins.

Synthesis of Well‐Defined Block Copolymers of Hyperbranched Polyamide and Polystyrene and Their Micelle‐to‐Vesicle Transformation in Organic Solvents

AbstractWell‐defined block copolymers consisting of hyperbranched polyamide (HBPA) and polystyrene (PSt) are synthesized, and their self‐assembled structures in solutions are investigated. Atom transfer radical polymerization (ATRP) of styrene initiated from an HBPA macroinitiator, prepared by the chain‐growth condensation polymerization of an AB2 monomer, followed by introduction of an ATRP initiator unit at the focal point, gives the desired block copolymers, PSt‐b‐HBPAs, with well‐defined molecular weight and narrow molecular weight distribution. The block copolymer (PSt/HBPA = 84/16) undergoes self‐assembly in toluene to form spherical micelles (≈10–20 nm), but upon addition of methanol to the toluene solution (toluene/methanol = 0.97/0.03), the morphology changes to vesicles. Further addition of methanol (toluene/methanol = 0.90/0.10) leads to an increase in vesicle size (200–300 nm) and the morphology further transforms from vesicles to large aggregates (>100 nm) at toluene/methanol = 0.80/0.20. In the case of PSt‐b‐HBPA with shorter PSt segments (PSt/HBPA = 76/24 and 60/40), spherical micelles are formed in toluene, but the micelle morphology remains unchanged when 10 wt% methanol is added, though large aggregates (>100 nm) are still formed in toluene/methanol = 0.80/0.20. Interestingly, the morphological transformations of linear/hyperbranched block copolymers are different from those of their double linear block copolymer counterparts.

Nonconventional Fluorescent Hyperbranched Polymer Dots as Skin Nanocarriers Constructed from an Olefinic Aliphatic AB2-Type Monomer

We constructed an olefinic aliphatic AB2 monomer (π-AB2) for the synthesis of a nonconventional fluorescent hyperbranched polymers (π-HBPs) through self-polymerization. We obtained π-AB2 from N-(3-aminopropyl)diethanolamine and maleic anhydride in three steps with a total yield of 79%. The π-HBPs possessed hyperbranched poly(amido acid) structures with internal alkene moieties, branched amino groups, and carboxyl terminal units. With their nonconjugated hyperbranched structures, the π-HBPs functioned as water-soluble polymer dots. Inter- and intramolecular hydrogen bonding in the π-HBPs resulted in a physically cross-linked structures displaying nonconventional fluorescence. This fluorescence arose from spatial conjugation at the molecular level, leading to clustering-induced emission with the lone pairs of electrons and the π-electrons interacting in a narrow confinement space. The emission of π-HBP 03 occurred at 460 nm upon excitation of 390 nm, with quantum yields of 13.5 and 7.5% at pH 7 and 3, respectively. From an examination of the relationship between chemical structure and photoluminescence, we found that the fluorescence emissions of the HBP without internal alkene moieties and π-HBP 03 (with internal alkene moieties) were 395 and 460 nm, respectively (a red-shift of 65 nm when removing the olefinic units). The self-assembly of π-HBP 03 in aqueous solution produced nanosized (ca. 9.1 nm) particles, as determined through dynamic light scattering. π-HBP 03 is noncytotoxic, with a cell viability of >90% at 1500 μg mL–1. When applied to percutaneous absorption mouse skin, the penetration ability of the π-HBPs increased in various time profiles according to the cluster size and nanostructure of the polymer dots. When we incubated HaCaT cells with π-HBP 03 for 24 h, confocal microscopy revealed that π-HBP 03 became located within the cells. Furthermore, assays revealed that π-HBP 03 displayed effective antioxidant abilities when employed at concentrations of 0.6 and 1.5 mg mL–1.

Hyperbranched Polyesters Based on Indole- and Lignin-Derived Monomeric Aromatic Aldehydes as Effective Nonionic Antimicrobial Coatings with Excellent Biocompatibility.

This research aims to investigate nonionic hyperbranched polyesters (HBPs) derived from indole and lignin resources as new nontoxic antimicrobial coatings. Three nonionic HBPs with zero to two methoxy ether substituents on each benzene ring in the polymer backbones were synthesized by melt-polycondensation of three corresponding AB2 monomers. The molecular structures and thermal properties of the obtained HBPs were characterized by gel permeation chromatography, nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry analyses. These HBPs were conveniently spin-coated on a silicon substrate, which exhibited significant antibacterial effect against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis). The presence of methoxy substituents enhanced the antimicrobial effect, and the resulting polymers showed negligible leakage in water. Finally, the polymers with the methoxy functionality exhibited excellent biocompatibility according to the results of hemolysis and MTT assay, which may facilitate their biomedical applications.

New applications of diffusion model based prediction of pathological brain alterations: Introducing amyloid‐tau interactions

AbstractBackgroundAlzheimer’s disease involves widespread and progressive deposition of misfolded protein tau. There is mounting evidence for “prion‐like” trans‐neuronal transmission, whereby proteins misfold, triggering subsequent misfolding of adjacent same‐species proteins, which spread along white matter projections. It is not well understood how tau and amyloid beta interact, and how their subsequent spread lead to stereotypical progression in the Alzheimer brain.MethodHere we present a major advancement of our previously established Network Diffusion Model (Raj et al. Neuron 2012) that includes three key processes: a) Tau monomer seeding and production in the entorhinal cortex, and Ab monomer seeding in metabolically active areas. b) Interaction between Ab and tau, whereby Ab facilitates production of tau, or both facilitate each other. c) Both species then undergo network spread via our prior Network‐Diffusion model, whereby anatomic connections govern the rate at which two distant but connected brain regions can transfer pathologic species. This extended joint Ab‐tau model was thoroughly tested on empirical group‐averaged regional data (MRI‐derived atrophy, AV45‐PET for Ab and AV1451‐PET for tau) from ADNI‐3 (Table 1).ResultThe extended NDM model exhibits all hallmarks of tau and amyloid progression seen in human patients (Figure 1), accurately capturing the spatial distribution of empirical regional atrophy, Ab and tau (Table 2). Figure 1 shows evolution of the joint model with (middle column) and without amyloid‐facilitation of tau (right). Remarkably, the introduction of a 1‐way directed Aβ to tau influence recapitulated the concept of amyloid‐facilitated tauopathy, and was critical to the models’ success. In comparison, the non‐interacting model was significantly worse, while the 2‐way interaction model (bidirectional influence between tau and Ab) was essentially the same (see Table 2).ConclusionThis in silico exposition of the “pas de deux” of co‐evolving proteins supports a key role for an amyloid‐facilitated‐tau rather than the classic amyloid‐cascade or pure‐tau hypotheses, and helps explain known but poorly understood aspects of AD (Figure 2).

Branched copolylactides: the effect of the synthesis method on their properties

In this work, L-lactide, acting as a cyclic AB monomer, was copolymerized with various AB2 comonomers. Depending on the nature of the AB2 comonomer, it was either a combination of L-lactide ring-opening polymerization with glycidol polymerization or a combination of L-lactide ring-opening polymerization with 2,2-bis (hydroxymethyl) propionic acid (BHP) polycondensation. Both synthetic methods resulted in branched copolyesters. A number of polymers with varying degrees of branching were obtained by systematically changing the proportion of comonomer AB2. The polymers were characterized using 1H NMR spectroscopy and SEC, and their thermal properties were studied using differential scanning calorimetry and thermogravimetric analysis. Also were investigated the viscosity of the solution and the wettability of the branched copolymers. Although structurally similar macromolecules were formed in both synthesis methods, polymers with BHP as AB2 comonomers have higher melting- and glass transition temperatures, higher thermal stability, solution viscosity and lower wettability than polymers with glycidol as AB2 comonomers.

Clickable 2,2‐bis(hydroxymethyl)propionic acid‐derived AB2 monomers: Hyperbranched polyesters through the CuAAC cycloaddition (click) reaction

AbstractWe present the synthesis and characterization of two aliphatic AB2 monomers derived from the readily available 2,2‐bis(hydroxymethyl)propionic acid and containing one alkyne group and two azide functionalities. The distance between the polymerizable groups differs in the two monomers by the insertion of an additional carbon atom in the aliphatic structure that addresses the steric demand during polymerization. The synthetic procedure for the monomers is relatively simple and scalable, and the monomers are able to polymerize through the Copper(I)‐catalyzed Azide‐Alkyne Cycloaddition (CuAAC reaction). The polymerization affords hyperbranched polymers in good yields and molecular weights and moderate degrees of branching. Copyright © 2021 John Wiley & Sons, Ltd.

Effect of hyperbranched polycarboxylic acid superplasticiser on the properties of cement paste

Comb-like polycarboxylate is a superplasticiser possessing a high water reducing rate and excellent molecular design, and has been widely used in the concrete industry. Most research studies have adjusted the effect of the superplasticiser by improving the groups on the superplasticiser molecular chain, but few studies have been carried out that change the structure of the comb molecular chain. AB2 monomer was prepared by the Michael addition reaction of diethanolamine and methyl acrylate, and hyperbranched polymer was prepared with trihydroxypropane as the core. In this paper, an advanced hyperbranched polycarboxylate, which was modified by a hyperbranched polyamine-ester, was designed as a superplasticiser. The hyperbranched polycarboxylic acid superplasticiser has the advantage of improving the rheological properties of cement slurry and the strength of mortar test blocks, compared with the traditional polycarboxylate superplasticiser; this is attributed to the hyperbranched polymers that provide hydroxyl groups and enhance the molecular spatial structure.

Synthesis of a New Hyperbranched Pyridylphenylene Polymer Based on an АB2 Monomer and a Pair of АB/АB2 Monomers

A hyperbranched pyridylphenylene polymer with the weight average molecular mass of 56000 Da is synthesized for the first time from an AB2 monomer bearing one diene and two internal triple bonds. The introduction of a linear AB comonomer into the reaction system leads to an increase in the yield of the polymer which has the weight average molecular mass of 21400 Da. Due to the limited degree of intramolecular cyclization, the high content of functional groups facilitates the formation of defect-free structures and provides an opportunity to modify the resulting polymers.

Synthesis of Heterofunctional Polyester Dendrimers with Internal and External Functionalities as Versatile Multipurpose Platforms.

Heterofunctional dendrimers with internal and external representations of functionalities are considered as the ultimate dendritic frameworks. This is reflected by their unprecedented scaffolding, such as precise control over the structure, molecular weight, number, and location of different cargos across the whole dendritic skeleton. Consequently, these dendrimers with multipurpose characters are the pinnacle of precision polymers and thereof are highly attractive to the scientific community as they can find use in a great number of cutting-edge applications, especially as discrete unimolecular carriers for therapeutic exploitation. Unfortunately, most established dendrimer families display external functionalities but lack internal scaffolding ability, which leads to inherent limitations to their full potential use as precision carriers. Consequently, here, we embark on a novel synthetic strategy facilitating the introduction of internal functionalization of established dendrimers. As a proof of concept, a new class of internally and externally functionalized multipurpose dendrimers based on the established 2,2-bis(methylol)propionic acid (bis-MPA) was successfully obtained by the elegant and simple design of AB2C monomers, amalgamated from two traditional AB2 monomers. Utilizing fluoride-promoted esterification (FPE), straightforward layer-by-layer divergent growth up to the fourth generation was successful in less than one day of reaction time, with a molecular weight of 15 kDa, and displaying 93 reactive groups divided by 45 internal and 48 external functionalities. The feasibility of postfunctionalization through click reactions is demonstrated, where the fast and effective attachment of drugs, dyes, and PEG chains is achieved, as well as cross-linking into multifunctional hydrogels. The simplicity and versatility of the presented strategy can easily be transferred to generate a myriad of functional materials such as polymers, surfaces, nanoparticles, or biomolecules.

Selective monobenzylation of 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) to yield an AB linear monomer and analogous linear oligomers

The synthesis of a mono-benzylated AB monomer based on bis-MPA is explored and accomplished via a three-step synthesis without column chromatography. This optimized synthesis utilizes a generic acid-catalyzed esterification of bis-MPA to the ethyl ester. Subsequently, a selective mono-benzylation mediated by silver(I) oxide affords the monobenzyl ether of the ethyl ester. Finally, a simple base hydrolysis of monobenzyl ether ethyl ester yields 3-(benzyloxy)-2-(hydroxymethyl)-2-methylpropanoic acid, the AB monomer. This synthesis was utilized to generate gram quantities of the linear monomer (47% yield) and this monomer was used to produce a small amount of the linear polymer analogs. Although there are many branched analogs of bis-MPA, this is the first linear oligomer that has been confirmed.