Divinyl Adipate Research Articles

Degradable biporous polymeric networks based on 2-methylene-1,3-dioxepane: Towards hierarchically structured materials meant for biomedical applications

For the first time, the preparation of doubly porous “poly(ε-caprolactone)-like” networks through free-radical ring-opening copolymerization of 2-methylene-1,3-dioxepane with divinyl adipate was achieved via a double porogen templating approach. This versatile strategy allowed for the formation of macropores of around 150 μm generated by removal of sieved and sintered NaCl particles in water, while smaller pores in the 1–10 μm range were created by phase separation during the copolymerization process through a syneresis mechanism in the presence of a porogenic solvent. The chemical nature of the as-obtained scaffolds was evidenced by Raman spectroscopy. The two distinct porosity levels could be examined by scanning electron microscopy and mercury intrusion porosimetry. The nature of the porogenic solvent as well as its volume proportion and the amount of crosslinking agent in the polymerization feed allowed for finely tuning the porous features of the micropores. The crucial role of the double porosity of such biporous scaffolds on their water uptake and mechanical properties under compression was assessed by comparing them with their monoporous analogues, while their degradability was investigated in different alkaline aqueous media. The double porosity enabled a synergistic effect regarding the water uptake of the resulting scaffolds when compared to their monoporous counterparts. Doubly porous polymeric materials with appropriate mechanical properties were obtained, possessing high compressibility and shape memory behavior upon consecutive compression cycles. Finally, these materials display degradation rates that could be controlled depending on medium pH.

Synthesis of linear polyesters bearing amino groups via lipase-catalyzed polymerization of N-protected monomer and deprotection

Linear biodegradable polyesters with a controlled number of side chains of amino groups have been synthesized. Such polyesters with a large number of amino side groups can be conjugated with a wide variety of functional molecules to obtain multi-functional biodegradable polyesters. In this study, poly(1,3-propylene-co-2-amino-1,3-propylene) adipate) (P(P-co-AP)A) was synthesized by enzymatic polymerization of divinyl adipate, 1,3-propanediol, and N-Boc-2-amino-1,3-propanediol (BocAPDO), and subsequent deprotection under strong acidic conditions. The mild reaction conditions and the specificity of the enzymatic polymerization could effectively inhibit side reactions, while the protecting groups of the monomers prevented polymer branching from the amino groups. It was found that the introduction rates of BocAPDO in the polymers could be well-controlled as the feeding rates changed from 0 to 100 mol%. After the deprotection and desalting, the ester groups in the main chain gradually converted into amide groups by intramolecular ester aminolysis at room temperature for a few days due to nucleophilic free amino groups. It was also found that the synthesized functional copolymers were all amorphous, since the random component of amino groups disrupted the crystallinity of poly(1,3-propylene adipate) (PPA). The glass transition temperature gradually increased with the increase in the content of 2-amino-1,3-propylene adipate (APA), eventually reaching −0.4 °C at the APA content of 100 mol% due to the intermolecular hydrogen bonding. Moreover, P(P-co-AP)A shows high hygroscopicity, where 3.9 wt% and 8.1 wt% of water were absorbed in the polymers with the APA contents of 50 and 100 mol%, respectively, when left in air at 60–70 % humidity for 6 h. Thus, the hydrophilicity dramatically improved with the increase in the APA content, eventually resulting in the acquisition of water solubility. The model post-polymerization modification using butyric acid was also conducted, and it was confirmed that carboxylic acids could be conjugated to the polymers by simple condensation reaction. Since polymerization of functional monomers is generally susceptible to the polarity of metal catalysts, the mild and selective reaction employed in this study could realize a higher content of various functional groups in the side chains of polyesters leading to a newly designed multi-functional polyester.

Straightforward Enzymatic Methacrylation of Poly(Glycerol Adipate) for Potential Applications as UV Curing Systems.

Enzymatic one-pot synthesis procedures in a one-step and two-step monomers addition were developed to obtain poly(glycerol adipate) macromers with methacrylate end-functional groups under the presence of 1 and 3 wt% of Candida antarctica lipase B (CALB). Glycerol, divinyl adipate, and vinyl methacrylate were enzymatically reacted (vinyl methacrylate was either present from the beginning in the monomers solution or slowly dropped after 6 h of reaction) in tetrahydrofuran (THF) at 40 °C over 48 h. Macromers with a methacrylate end groups fraction of ≈52% in a simple one-pot one-step procedure were obtained with molecular weights (Mn) of ≈7500-7900 g/mol. The obtained products under the one-pot one-step and two steps synthesis procedures carried out using 1 and 3 wt% of a CALB enzymatic catalyst were profusely characterized by NMR (1H and 13C), MALDI-TOF MS, and SEC. The methacrylate functional macromers obtained with the different procedures and 1 wt% of CALB were combined with an Irgacure® 369 initiator to undergo homopolymerization under UV irradiation for 10 and 30 min, in order to test their potential to obtain amorphous networks within minutes with similar properties to those typically obtained by complex acrylation/methacrylation procedures, which need multiple purification steps and harsh reagents such as acyl chlorides. To the best of our knowledge, this is the first time that it has been demonstrated that the obtention of methacrylate-functional predominantly linear macromers based on poly(glycerol adipate) is able to be UV crosslinked in a simple one-step procedure.

Enzymatic acylation improves the stability and bioactivity of lutein: Protective effects of acylated lutein derivatives on L-O2 cells upon H2O2-induced oxidative stress

The instability of lutein has limited its wide application especially in the food industry. In this study, enzymatic acylation of lutein with divinyl adipate was investigated. Three new acylated lutein derivatives, lutein-3-O-adipate (compound 1), lutein-3′-O-adipate (compound 2) and lutein-di-adipate (compound 3), were identified and their stabilities and bioactivates were evaluated. Notably, compounds 1–3 showed better thermal, light stability and stronger scavenging capacity to ABTS radical cation (ABTS+) and hydroxyl radical (OH). Most importantly, these acylated lutein derivatives exhibited excellent protective effects on L-O2 cells upon hydrogen peroxide (H2O2)-induced oxidative stress. In particular, the acylated lutein derivative termed compound 3 prevented cellular oxidative stress via restraining the overproduction of reactive oxygen species (ROS), thereby increasing related antioxidant enzymes activity and inhibiting apoptosis by mitochondria pathway. Our research provides important insights into the application of acylated lutein derivatives in food, cosmetic, and pharmaceutical products.

Glycerol-based enzymatically synthesized renewable polyesters: Control of molecular weight, degree of branching and functional endgroups

The catalytic specificity of Lipase B from Candida antarctica (CALB) has been exploited to achieve specific terminal groups for the synthesis of glycerol poly(ester)s. This permits the preparation of glycerol-derived macromers able to undergo further reactions/chemical modifications for customization as functional systems and building blocks for polymer synthesis. Poly(glycerol adipate) based macromers with different terminal structures were achieved from the reaction between glycerol and divinyl adipate by varying the stoichiometry (from equimolar to 1.5 and 3.0 excess either of glycerol or divinyl adipate) and amount of catalyst (1 and 3 wt%). In the course of polymerization, transesterification and hydrolysis reactions occur over vinyl functionalities that result in acid endgroups. Thus, the resulting macromers are either terminated with hydroxyl groups and/or acid groups and/or vinyl groups. Therefore, an understanding of how acid functionality appears (from vinyl groups hydrolysis) and its quantification under various conditions may provide an opportunity for the design of synthetic strategies to avoid acid production and obtain the desired structures. Endgroup analysis was carried out using 1H NMR and 13C NMR spectroscopies and MALDI-TOF spectrometry. Mainly linear hydroxyl and vinyl-terminated macromers were obtained with high efficiency without significant hydrolysis of the chain ends (for vinyl terminated).

Emulsion Templated Porous Poly(thiol-enes): Influence of Photopolymerisation, Emulsion Composition, and Phase Behaviour on the Porous Structure and Morphology.

1,6-hexanediol diacrylate (HDDA) or divinyl adipate (DVA) and pentaerythritol tetrakis(3-mercaptopropionate) (TT) were polymerised via a thiol-ene radical initiated photopolymerisation using emulsions with a high volume fraction of internal droplet phase and monomers in the continuous phase as precursors. The porous structure derived from the high internal phase emulsions (HIPEs) followed the precursor emulsion setup resulting in an open porous cellularly structured polymer. Changing the emulsion composition and polymerisation conditions influenced the resulting morphological structure significantly. The investigated factors influencing the polymer monolith morphology were the emulsion phase ratio and surfactant concentration, leading to either interconnected cellular type morphology, bicontinuous porous morphology or a hollow sphere inverted structure of the polymerised monoliths. The samples with interconnected cellular morphology had pore diameters between 4 µm and 10 µm with approx. 1 µm sized interconnecting channels while samples with bicontinuous morphology featured approx. 5 µm wide pores between the polymer domains. The appropriate choice of emulsion composition enabled the preparation of highly porous poly(thiol-enes) with either polyHIPE or bicontinuous morphology. The porosities of the prepared samples followed the emulsion droplet phase share and could reach up to 88%.

Enzymatic synthesis of hydrophilic phytosterol polyol esters and assessment of their bioaccessibility and uptake using an in vitro digestion/Caco-2 cell model

A novel enzyme-catalyzed method was developed for the synthesis of phytosterol polyol esters from β-sitosterol and polyols (sorbitol, mannitol and xylitol) by two-step transesterification using divinyl adipate (DVA) as a link. A high conversion (exceeding 94%) of β-sitosterol with a vinyl group was achieved, in the presence of Candida rugosa lipase (CRL), at low temperature (35 °C) within 30 min. Subsequently, the maximum conversion of phytosterol polyol esters (>94%) was obtained using alkaline protease from Bacillus subtilis at 65 °C. Phytosterol polyol esters had enhanced thermal stability (up to an above 355 °C) and excellent water solubility (4.6–7.9 mM at 35 °C). Moreover, obvious increases in the bioaccessibility (41.5–63.6%) and intestinal uptake (5.2–6.5%) were observed using a simulated gastrointestinal digestion/Caco-2 cell model. These results highlighted the key role of hydrophilic structural modifications on physicochemical properties and absorption of phytosterols.

Lipase‐catalyzed synthesis of epigallocatechin gallate‐based polymer for long‐term release of epigallocatechin gallate with antioxidant property

ABSTRACTEpigallocatechin gallate (EGCG) must be released in a controlled manner in order to maximize its long‐term potential as an antioxidant. In this study, lipase‐catalyzed polymerization of EGCG with divinyl adipate and sugar alcohols was conducted to form polyEGCG, which enables long‐term controlled release of EGCG via hydrolysis of ester linkages. The polymer yields were influenced by monomer ratios, volume of solvent, and lipase concentration. EGCG was gradually released from polyEGCG under a physiological condition as ester groups of polyEGCG degraded over a period of more than two months, and the releasing rate was influenced by the type of the sugar alcohols and EGCG ratios. EGCG released from polyEGCG maintained its antioxidant activity and the cell viability of polyEGCG eluent with polymer concentration higher than 0.05 mg/mL was as high as 100%. These results indicate that polyEGCG has potential application as a highly efficient and long‐term antioxidative material with low cytotoxicity. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47693.

Multiple grafting to enzymatically synthesized polyesters.

Enzymatic polymerization is an environmentally benign process for the synthesis of biodegradable and biocompatible polymers. The regioselectivity of lipase B from Candida Antarctica (CAL-B) produces linear functional polyesters without protection-deprotection steps. In this work, two different methods for the enzymatic synthesis of functional polyesters based on renewable resources, as, e.g., glycerol, using CAL-B are outlined. Poly(glycerol adipate) was synthesized by enzymatic transesterification between glycerol and divinyl adipate or dimethyl adipate. Methods are also reported to graft poly(glycerol adipate) with different amounts of hydrophobic side chains (lauric, stearic, behenic, and oleic acids) and hydrophilic poly(ethylene glycol) side chains, respectively. The hydrophilicity or lipophilicity of grafted polyesters is well controlled by changing the degree of grafting of hydrophilic and hydrophobic side chains. The multiple grafted polyesters are characterized by NMR spectroscopy, differential scanning calorimetry, gel permeation chromatography, and X-ray diffraction. Furthermore, the self-assembly of the graft copolymers in water and their use as steric stabilizers for cubosomes are discussed. For this purpose mainly dynamic light scattering and small angle X-ray scattering have been employed.

Preparation of Polyester PolyMIPEs by Polycondensation of Low-Molecular Weight Polyol and Divinyl Ester Using Microwave Activation.

Several stable non-aqueous apolar-in-polar medium internal phase emulsions (MIPEs) containing divinyl adipate and pentaerythritol in the continuous phase are formulated by varying the nature of the hydrocarbon. Polycondensation is then conducted either under conventional heating or microwave irradiation after addition of a commercially available organocatalyst. Solvent elimination and drying lead to the corresponding polyester polyMIPEs. A tremendous morphological difference between materials is observed according to the heating method employed. The particular efficiency of microwave activation in the polycondensation of the continuous phase of a non-aqueous emulsion is discussed.

Properties of acyl modified poly(glycerol-adipate) comb-like polymers and their self-assembly into nanoparticles.

ABSTRACTThere is an increasing need to develop bio‐compatible polymers with an increased range of different physicochemical properties. Poly(glycerol‐adipate) (PGA) is a biocompatible, biodegradable amphiphilic polyester routinely produced from divinyl adipate and unprotected glycerol by an enzymatic route, bearing a hydroxyl group that can be further functionalized. Polymers with an average Mn of ∼13 kDa can be synthesized without any post‐polymerization deprotection reactions. Acylated polymers with fatty acid chain length of C4, C8, and C18 (PGAB, PGAO, and PGAS, respectively) at different degrees of substitution were prepared. These modifications yield comb‐like polymers that modulate the amphiphilic characteristics of PGA. This novel class of biocompatible polymers has been characterized through various techniques such as FT‐IR, 1H NMR, surface, thermal analysis, and their ability to self‐assemble into colloidal structures was evaluated by using DLS. The highly tunable properties of PGA reported herein demonstrate a biodegradable polymer platform, ideal for engineering solid dispersions, nanoemulsions, or nanoparticles for healthcare applications. © 2016 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3267–3278

Enzymatic Synthesis and Characterization of Hydrophilic Sugar Based Polyesters and Their Modification with Stearic Acid.

Biodegradable and hydrophilic functional polyesters were synthesized enzymatically using xylitol or d-sorbitol together with divinyl adipate and lipase B from Candida antartica (CAL-B). The resulting polyesters had pendant OH-groups from their sugar units which were esterified to different degrees with stearic acid chloride. The structure and the degrees of polymerization of the resulting graft copolymers based on poly(xylitol adipate) and poly(d-sorbitol adipate) were characterized by 1H NMR spectroscopy and SEC. DSC, WAXS and SAXS measurements indicated that a phase separation between polymer backbone and stearoyl side chains occurred in the graft copolymers, and, additionally, the side chains were able to crystallize which resulted in the formation of a lamellar morphology. Additionally, nanoparticles of the graft copolymers in an aqueous environment were studied by DLS and negative stain TEM.

Variation in structure and properties of poly(glycerol adipate) via control of chain branching during enzymatic synthesis

Poly (glycerol adipate) (PGA) can be produced from divinyl adipate and unprotected glycerol by an enzymatic route to generate a polymer with relatively low molar mass (12 kDa). PGA bears a pendant hydroxyl group which imparts a hydrophilic character to this water insoluble polymer. We have examined the effect of synthesis temperature on polymer characteristics through various techniques including FT-IR, 1H and 13C NMR, surface and thermal analysis, both to expand the data already present in the literature about this material and to understand better its properties for potential pharmaceutical applications. The use of a lipase (Novozym 435) as a catalyst suppresses cross-linking at the pendant glyceryl hydroxyl through steric hindrance at the active site, thus producing polymers with low degrees of branching (5–30%), and removes the need for any pre- or post-polymerization protection/deprotection reactions. Careful temperature control during synthesis can give polymers with reproducible molecular weights and reduced amounts of polymer branching compared to synthesis at higher temperatures. Due to the ability of the synthetic route to produce a range of structures, PGA generated by enzymatic routes may emerge as a useful biodegradable polymer platform to engineer solid dispersions or nanoparticles for healthcare applications.

Additive manufactured, biocompatible hydrogels based on hyaluronic acid

Event Abstract Back to Event Additive manufactured, biocompatible hydrogels based on hyaluronic acid Stefan Baudis1, Zuzana Tomášiková1, Elise Zerobin1, Xiao-Hua Qin1, Jürgen Stampfl2, Aleksandr Ovsianikov2 and Robert Liska1 1 Vienna University of Technology, Institute of Applied Synthetic Chemistry, Austria 2 Vienna University of Technology, Institute of Materials Science and Technology, Austria Introduction: Hyaluronic acid (HA) is a polysaccharide, a major component in the extracellular matrix (ECM), and the basis of a large number of bio-inspired materials. In order to produce photo-crosslinked, biocompatible hydrogels it is necessary to introduce double bonds to the polysaccharide back bone. (Meth)acrylate-functionalization, however, is unsuitable due to the inherent cytotoxicity. The low cytotoxicity of vinyl esters along with the superior photo-reactivity as thiol-ene system[1] makes vinyl ester-functionalized HA an interesting candidate material for 3D biomaterial constructs manufactured by laser fabrication using two-photon lithography. Materials and Methods: HA vinyl esters (HA-VE) were synthesized from HA with different molecular weights by lipase catalyzed transesterification with divinyl adipate (DVA) (Scheme 1)[2]. Macromeres were formulated with varied macromere contents and their reactivity was examined by photorheology. Furthermore, the influence of the addition of dithiothreitol (DTT) as chain transfer agent (CTA) was investigated. The slope of the storage modulus from rheometric curves was taken as a measure for the reactivity whereas the final storage modulus was used to calculate the mesh size of the hydrogels as reference value for the crosslink density. Additionally, the swellability of ready-cured hydrogels was determined. Cell compatibility of HA-VEs were assessed by metabolic as well as DNA assays. An exemplary HA-VE based formulation was used for the encapsulation of human umbilical vein cells (HUVECs) by two-photon polymerization (2PP) based microfabrication. The viability of the encapsulated cells was assessed by LIVE/DEAD staining. Results: Two HA batches with different m.w. were converted to HA-VEs with different degrees of substitution (DS) resulting in six batches of HA-VE with different macromere size and DS. Photo-reactivity increased with macromere content, macromere size, and DS. Crosslink density followed the same trend, however, it was found that 80 mol% of thiol led to an optimized reactivity and final storage modulus. Swellability of hydrogels is decreased with increasing DS. Metabolic as well as DNA assay indicated the same trend for the cytocompatibility of vinyl ester-modified HA. The influence of the number of vinyl ester-groups (represented by DS) on the cytotoxicity of HA-VEs was found to be negligible. As a proof of the concept HUVECs were encapsulated in 3D hydrogel constructs[3] and found to be viable after 24 and 96 h (Figure 1). Discussion: HA can be transformed to biocompatible HA-VE by lipase-catalyzed transesterification reaction with DVA in high yields. DS is easily adjusted by consideration of the reaction time. By variation of macromere content, macromere size, and/or DS the material properties can be adjusted and adapted to the demands. The cytocompatibility of the synthesized macromeres enables the fabrication of 3D hydrogel constructs with encapsulated cells by laser fabrication using two-photon lithography. Conclusion: The modification of HA with vinyl esters in order to obtain macromeres that can be polymerized on demand by photopolymerization was found to be a promising modular material platform to engineer 3D hydrogel constructs as environment for living cells by laser based additive manufacturing technologies. Austrian research funding association (FFG, project number 849787); European Research Council (Starting Grant-307701, A.O.)

Green polymer chemistry: synthesis of symmetric and asymmetric telechelic ethylene glycol oligomers

Kinetic investigation of the enzyme-catalyzed polycondensation of divinyl adipate and TEG led to the optimization of end group structures (vinyl V and OH O).

L-Arabinose (pyranose and furanose rings)-branched poly(vinyl alcohol): Enzymatic synthesis of the sugar esters followed by free radical polymerization

Herein this study reports the successful synthesis of a new poly(vinyl alcohol) (PVA), containing L-arabinose (L-arabinopyranose and arabinofuranose isomers) branched in only two steps: (1) production of polymerizable monomers of L-arabinose isomers (pyranose and furanose forms) through enzymatic synthesis using alkaline protease from Bacillus subtilis as catalyst and two substrates: L-arabinose and Divinyl Adipate (DVA) in N,N-dimethylformamide (DMF); (2) radical polymerization of the monomers, using an initiator system consisting of potassium persulfate and hydrogen peroxide in water. The transesterification of DVA with L-arabinose was monitored via qualitative analysis by TLC, confirming the formation of the vinyl sugar ester. The acylation occurred on the two different cyclic conformations of the L-arabinose which coexist in equilibrium: (α/β) arabinofuranose and (α/β) arabinopyranose. The acylation positions and the chemical structure of the 5-O-vinyl adipoyl L-arabinofuranose and 4-O-vinyl adipolyl L-arabinopyranose formed were determined by 13C NMR. The surface activity of the L-arabinose esters mixture (monomers) was compared with a commercial product based on phenol formaldehyde polyoxyalkylene polyamine, largely used as surfactant in many industries. FTIR spectroscopy of the sugar ester monomers and the respective polymer were compared revealing the disappearance of the vinyl group in the polymer spectrum. The polymer number-average molar mass (Mn) and the weight-average molar mass (Mw) were determined by gel permeation chromatography (GPC) presenting the following results: 2.9×104Da and 7.2×104Da, respectively, and polydispersity (Mw/Mn) equal to 2.48.

Microcellular open porous monoliths for cell growth by thiol-ene polymerization of low-toxicity monomers in high internal phase emulsions.

Open porous microcellular polymers with high degrees of porosity are prepared from divinyl adipate and pentaerythritol tetrakis(3-mercaptopropionate) by thiol-ene polymerization within high internal phase emulsions. The influence of monomer ratio, droplet phase volume, and emulsion stirring rate on the morphology and mechanical properties of the products is studied. The newly produced material is successfully applied as a scaffold for osteoblastic MC3T3-E1 cells in vitro, showing increased rates of cell growth compared to material prepared by standard methods.

Synthesis of functionalized polyisobutylenes using the propylene epoxide/TiCl4initiating system

In this paper, we report the synthesis of symmetric and asymmetric telechelic polyisobutylenes (PIBs). A PIB with a primary hydroxy head group and an allyl end group (HO–PIB–Allyl, Mn = 4300 g mol−1; Mw/Mn = 1.2) was synthesized by living carbocationic polymerization of isobutylene (IB) using propylene epoxide as an initiator and allyltrimethylsilane as a terminating agent. Thiol–ene click chemistry using 2-mercaptoethanol and 1,2-ethanedithiol yielded an asymmetric HO–PIB–SEt–OH (Mn = 4646 g mol−1; Mw/Mn = 1.18) and a symmetric HO–PIB–OH (Mn = 8594 g mol−1; Mw/Mn = 1.2) respectively. A symmetric allyl telechelic PIB (Mn = 8669 g mol−1; Mw/Mn = 1.2) was prepared by enzymatic transesterification of divinyl adipate with the primary hydroxy group of HO–PIB–Allyl.

Enzyme-catalyzed quantitative chain-end functionalization of poly(ethylene glycol)s under solventless conditions

This is the first report of quantitative vinyl chain-end functionalization of poly(ethylene glycol)s (PEGs) with reduced environmental effects and renewable catalysis. Divinyl adipate (DVA) was transesterified using Candida antarctica lipase B (CALB) supported on an acrylic resin at 50 °C under dry nitrogen and solventless conditions. After the reactions CALB was removed by filtration and excess DVA was recovered by hexane extraction followed by distillation for reuse. 1H and 13C NMR spectroscopy and MALDI-ToF mass spectrometry was used to analyze the structure and purity of the products. The effects of DVA excess and PEG chain length were investigated. Model experiments with tetra(ethylene glycol) (TEG) led to polycondensation. At DVA/TEG 20/1 molar ratio ∼82% of the product was Vinyl–TEG–Vinyl, together with vinyl-telechelic dimers and trimers. When reacting monomethoxy MeO–PEG–OH of Mn = 1100 g mol−1 under the same conditions, pure MeO–PEG–Vinyl was obtained with no coupling. MeO–PEG–OH with Mn = 2000 g mol−1 gave pure MeO–PEG–Vinyl at 5 molar excess of DVA. With HO–PEG–OH1000 of Mn = 1000 g mol−1 at DVA/PEG 20/1 molar ratio no polycondensation and only 2% coupled product was found, while HO–PEG–OH with Mn = 2000 g mol−1 under the same conditions gave pure telechelic Vinyl–PEG–Vinyl.

Synthesis and Characterization of Stearoyl Modified Poly (Glycerol Adipate) Containing ATRP Initiator on its Backbone

Poly (glycerol adipate) is enzymatically prepared by reacting glycerol with divinyl adipate in the presence of a lipase as catalyst fromCandida Antarcticatype B (CAL-B). The reaction yields linear polyesters with free pendent hydroxyl groups. Poly (glycerol adipate) is hydrophobically modified by incomplete acylation of some of the pendent hydroxyl groups using stearoyl chloride. The resulting polymer is further functionalized with α-bromoisobutyryl groups. The final polymer is purified and well characterized to calculate the ratio of substitution in both cases. Furthermore, nanoparticles in water are prepared from the functionalized polymer using the interfacial precipitation method. Dynamic light scattering measurements depict nanoparticles with relatively narrow size distributions and with an average hydrodynamic radius of 70 nm. Additionally, transmission electron microscopy images reveal well dispersed spherical nanoparticles with nanophase separation. Finally, the interactions between the graft copolymers and lipid monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) are investigated on a Langmuir trough equipped with a fluorescence microscope.