An organic–inorganic hybrid polymer, composed of poly(methylsilsesquioxane) (PMSSQ) and poly(4‐vinyl benzaldehyde) (PStCHO), is prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization of 4‐vinyl benzaldehyde (StCHO) using a macro‐chain transfer agent (CTA) based on PMSSQ. The obtained PMSSQ–PStCHO is spin‐coated on substrates such as silicon wafers or copper plates to afford aldehyde‐functionalized surfaces. Successful Kabachnik‐Fields post‐polymerization modification (KF‐PMR) of the aldehyde‐functionalized surfaces is conducted with amines and dialkyl phosphonates, and characterized by surface analysis techniques including IR, energy‐dispersive X‐ray (EDX), and X‐ray photoelectron spectroscopy (XPS) measurements, documenting the installation of α‐amino phosphonates onto surfaces with practically quantitative conversion of aldehydes. In addition, the generated α‐amino phosphonates are successfully deprotected to afford the corresponding α‐amino phosphonic acids on surfaces, which make this route a reliable tool‐enabling surface functionalization with α‐amino phosphonic acids.
The preparation of novel nanoparticles is described, which consist of a poly(lactic acid) (PLA) core obtained by the nanoprecipitation method with a shell made of oppositely charged β‐cyclodextrin polymer (poly‐β‐CD) assembled using the layer‐by‐layer technique. Characterization of these nanoparticles is accomplished through dynamic light scattering, ζ‐potential measurements, X‐ray photoelectron spectroscopy and electron microscopy. The release of a loaded lipophilic molecule, benzophenone (BP), is mainly controlled by diffusion of BP and by its host–guest interaction with the β‐CD cavities of the adsorbed poly‐β‐CD. Increasing the number of poly‐β‐CD layers results in a better control of the release through the partition equilibrium between free BP and BP included in the cavities inside the multilayers.
The thermostable α‐glucan phosphorylase‐catalyzed enzymatic α‐glucuronylation and subsequent α‐glucosaminylation of glycogen using α‐d ‐glucuronic acid 1‐phosphate (GlcA‐1‐P) and α‐d ‐glucosamine 1‐phosphate (GlcN‐1‐P), respectively, produce amphoteric glycogens. The products exhibit the inherent isoelectric points, which change depending on the GlcA/GlcN ratios. Chain elongation of amyloses from the nonfunctionalized, nonreducing ends of the products through the thermostable α‐glucan phosphorylase‐catalyzed enzymatic polymerization of α‐d ‐glucose 1‐phosphate monomers is demonstrated to yield amphoteric glycogen hydrogels. The produced hydrogels exhibit pH‐responsive behavior.
Comb‐like copolymers based on a polyolefin backbone of poly(10‐undecene‐1‐ol) (PUol) with poly(ε‐caprolactone) (PCL) side chains are synthesized in two steps. After synthesis of PUol by metallocene‐catalyzed polymerization, the side‐chain hydroxyl functionalities of this polar polyolefin are used as an initiator for the ring‐opening polymerization (ROP) of ε‐caprolactone (CL). In this context, copolymers with different lengths of PCL grafts are prepared. The chemical structure and the composition of the synthesized copolymers are characterized by 1H and 13C NMR spectroscopy. It is shown that the hydroxyl end groups of PUol act effectively as initiating sites for the CL ROP. Size‐exclusion chromatography (SEC) measurements confirm the absence of non‐attached PCL and the expected increase in molar mass after grafting. The thermal and decomposition behaviors are investigated by DSC and thermogravimetric analysis (TGA). The effect of the length of the PCL grafts on the crystallization behavior of the comb‐like copolymers is investigated by DSC and wide‐angle X‐ray scattering (WAXS).
Using 22 metal triflates as catalysts, ε‐caprolactone is polymerized at 22 °C in bulk. Only five relatively acidic triflates prove active. Three triflates, including the neutral Sm3+, are active using water as initiator. A very low content of cyclics is found in all the experiments. With Ce3+ and Ce4+, polymerizations are performed in CH2Cl2 and in bulk at 2 °C and 22 °C. Low dispersities (down to 1.1) are obtained. At 22 °C, Ce4+ and, even better, Ce3+ also catalyze syntheses of CO2H‐ and CH2OH‐terminated polycaprolactones, whereby higher dispersities and larger fractions of cyclics are obtained. Further polymerizations and polycondensations are catalyzed with protic acids. The results can be explained by a proton‐catalyzed activated monomer mechanism.
A kind of γ‐(cyclodextrin) (γ‐CD)‐based polyrotaxane (PR) is synthesized via an aqueous click reaction between propargylamine‐substituted β‐CD and polypseudorotaxanes (PPRs) self‐assembled from azido‐endcapped PNIPAAm‐b‐Pluronic F68‐b‐PNIPAAm with a varying amount of γ‐CD. The evolution of the self assembly, dependent on the preparation process, is observable by X‐ray diffraction (XRD) and DSC analyses. The γ‐CD is able to be included and preferably entrapped on the PNIPAAm blocks, showing a unique loose‐fit aggregate structure after the click reaction. Most γ‐CDs gradually slip over to the middle PPG block of Pluronic F68, giving rise to a characteristic channel‐type crystal structure in the dialysis process. In addition, the lower critical solution temperature (LCST) is sharply enhanced due to the coverage of the remaining γ‐CDs hindering the thermally responsive aggregation of the PNIPAAm blocks.
A novel spacer‐free liquid crystalline polyrotaxane (LCPR) is synthesized by directly grafting 4‐phenylazobenzoyl chloride onto the hydroxyl of threaded α‐cyclodextrin (α‐CD) as the side‐chain. It is found that LCPR can form nematic LC phase above 180 °C or under the concentration of 5–0.2 wt% in dimethyl sulfoxide (DMSO) solution. The mechanisms of formation of thermotropic and lyotropic LC phase are proposed, respectively, which show the mobility of both threaded α‐CDs and substituted azo‐mesogens is responsible for the formation of LC phase. This mechanism is further demonstrated by the formation of crystalline phase under UV radiation, which is characterized by polarizing optical microphotograph and UV measurements.
Films of semicrystalline poly(ε‐caprolactone) (PCL) are fabricated by casting drops of fully biocompatible ethyl lactate (EL) and ethyl acetate (EA) solutions onto a glass substrate. The main goals of this work are: i) to assess the interplay among the physico‐chemical properties of the solution and its interaction with the casting substrate; and ii) determine how the solution/substrate interactions influence the formation of the films and their final surface morphology and hydrophilicity. The competition between the rates of solution drop spreading and solvent evaporation controls the polymer crystallization process and the final film properties. Compared with EA, EL provides better wetting properties and a slower evaporation rate, eventually resulting in thinner films. The film thickness increases with polymer concentration in the solution; this parameter also affects the crystalline structure and, ultimately, the film surface roughness. As a result, the film hydrophilicity is finely tunable by changing the solution composition, so as to control the crystal nucleation density.
Novel structural motifs in macromolecular chemistry are introduced by the use of the Asinger multicomponent reaction. The combination of ammonia, acetone, α‐chloroisobutyraldehyde, and either water or sodium hydrosulfide, leads to an oxazoline or thiazoline scaffold, respectively, which is subsequently modified with 10‐undecenol and 10‐undecenoyl chloride to obtain heterocycle‐functionalized α,ω‐dienes. These substrates are used as monomers in an acylic diene metathesis (ADMET) or thiol‐ene step‐growth polymerization. The thus‐obtained polymers are studied in post‐polymerization modifications, like hydrogenation and oxidation. Here, the thiazolidine‐ and oxazolidine‐containing polymers show dramatically different chemical stability due to the heterocyclic moieties.
The synthesis of high‐aspect‐ratio (AR) CdSe (NRs) nanorods and their ordered assembly over large areas are reported. Long‐range ordering of hexagonal arrays of high‐AR NRs is achieved by a combination of controlled solvent evaporation and the use of an applied electric field. Vertically oriented assemblies of CdSe NRs functionalized with oligo‐ and polythiophene are also obtained. Aligned and oriented polythiophene CdSe NRs have potential applications in organic–inorganic hybrid bulk‐heterojunction photovoltaic devices.
Randomly methylated β‐cyclodextrin (me‐β‐CD) is used to include the hydrophobic monomer N‐(4‐methylphenyl)maleimide (MPM) ( 1 ) yielding the corresponding water‐soluble host‐guest structure 1a . Free‐radical copolymerization of 1a with N‐vinylpyrrolidone (NVP) ( 2 ) is performed and the reactivity ratios r1 and r2 are determined: 0.24 ± 0.03 (r2) and 1.10 ± 0.05 (r1a). This indicates a preferred incorporation of complexed maleimide into the copolymer chain. In contrast to that, the copolymerization of the uncomplexed monomers 1 and 2 is carried out using organic solvent (DMF/H2O) showing reactivity ratios corresponding to nearly alternating copolymerization (r2 = 0.09 ± 0.02; r1 = 0.34 ± 0.03).
The control of reactivity of several bis(N‐glycidylsulfonamides) by aromatic substituents is presented. Therefore, disulfonamides with electron‐withdrawing or electron‐donating aryl moieties and a linear, branched, or oxygen‐substituted spacer are synthesized and further N‐alkylated with epichlorohydrin. Their curing times with N,N‐dimethyl aminopropyl amine in comparison with standard bisphenol A diglycidyl ether are measured by oscillatory rheology. A dependence of curing time with the Hammett σ‐value is found.
The Passerini three‐component reaction is applied to synthesize, in a one‐step procedure, diverse asymmetric α,ω‐dienes containing an acrylate and a terminal olefin. Such monomers are well known to undergo head‐to‐tail acyclic diene metathesis (ADMET) polymerization due to the high cross‐metathesis selectivity between acrylates and terminal olefins. Additionally, amphiphilic block copolymers are synthesized using a monofunctional PEG480 monoacrylate, which acts as a selective chain‐transfer agent during the polymerization process. Thus, control over the molecular weight of the amphiphilic ADMET polymers is shown by using different ratios of monomer and chain‐transfer agent. All the polymers are thoroughly characterized, and their ability to form nanoparticles in aqueous solution is studied.
A novel‐donor‐π‐acceptor‐type conjugated polymer based on the benzo[c][1,2,5]selenadiazole moiety and the fluorene group via an alkyne module is prepared by the the Sonogashira–Hagihara reaction. The polymer displays an absorption peak at a longer wavelength at 477 nm and shows orange fluorescence at 576 nm. The responsive optical properties of the polymer on various metal ions are investigated by fluorescence emission and UV–vis absorption spectroscopy measurements. Compared with other metal cations, Hg2+ shows the most pronounced UV–vis absorption and fluorescence response of the polymer. The visible color and the fluorescence color of the polymer sensor both disappear after addition of Hg2+, which can be easily detected by the naked eye. The results indicate this kind of polymer containing benzoselenadiazole units can be used as a highly selective and sensitive chemosensor for Hg2+ detection.
In the current investigation, nanocomposites containing a β‐nucleated poly(propylene‐co‐ethylene) (PPR) matrix filled with untreated (SiO2) and methacrylate‐modified silica nanoparticles (SiO2‐MAA) are prepared. Transmission electron microscopy (TEM) reveals the improvement in the quality of dispersion due to the surface modification of the nanoparticles. Also, from differential scanning calorimetry (DSC) and X‐ray diffraction (XRD), it is found that the β‐nucleating agent and silica nanoparticles work synergistically in order to increase the relative β‐content in the nanocomposite samples. The thermal stability of each samples is evaluated by means of thermogravimetric analysis (TGA) and the enhancement of the thermal stability of the nanocomposites is attributed to the nanoconfinement of the macromolecular chains caused by the presence of the fillers.
Novel branched polyoxymethylene copolymers are synthesized by cationic copolymerization of 1,3,5‐trioxane (TOX) with 3‐(alkoxymethyl)‐3‐ethyloxetane (ROX) using BF3·Et2O as an initiator. Four oxetane derivatives with different side‐chain lengths (from 1 to 6 carbons) are tested for copolymerization. The copolymer composition is controlled by the feed ratio of ROX, and influenced by the chain length of alkyl group on ROX. The incorporation ratio and side‐chain length of the ROX unit have great influence on the thermomechanical properties and crystallinity of the copolymers.
Electron‐acceptor units, combined with bithiophene substituted with flexible chains end‐functionalized with cross‐linkable moieties, provide soluble donor‐acceptor‐donor (DAD) π‐conjugated oligomer‐type molecules with cross‐linking ability and broad absorption in the visible spectrum. A study on the cross‐linking conditions of the new oligomers to yield insoluble polymer networks is presented, including conditions for obtaining polymer films over poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate‐covered substrates. The combination of the DAD molecular design and cross‐linking functionality opens prospects for applications in solution‐processed small‐molecule solar cells with morphologically‐stable organic layers.
Two novel chiral β‐ketoiminate‐based boron hybrid polymers, P‐1 and P‐2, are synthesized from a chiral β‐ketoiminate‐based boron hybrid complex ( M‐1 ), with 1,4‐dioctyl‐2,5‐diethynylbenzene ( M‐2 ) and 3,6‐diethynyl‐9‐octyl‐9H‐carbazole ( M‐3 ), respectively, via a Pd‐catalyzed Sonogashira coupling reaction. The resulting polymers P‐1 and P‐2 show strong fluorescence emission centered at 525 nm and 534 nm with large Stokes’ shifts and high quantum yields. Most importantly, compared with the circularly polarized luminescence (CPL) dissymmetry factor (glum = +0.042) of chiral small model molecules, P‐1 and P‐2 can exhibit a large glum as high as +0.105 and +0.349 in CH2Cl2 solution, which can be attributed to the amplification effect of CPL arising from the conjugated polymer structure.
A series of multiarmed and multicomponent miktoarm (μ‐) star polymers have been successfully synthesized by developing a new iterative methodology based on a specially designed linking reaction of the block copolymer in‐chain anions, whose anions are positioned between the blocks, with α‐phenylacrylate (PA)‐functionalized polymers. The iterative methodology involves the following two reaction steps: a) introduction of two different polymer segments by the linking reaction of a block copolymer in‐chain anion with a PA‐functionalized polymer and b) regeneration of the PA reaction site. By repeating this reaction sequence, two different polymer segments are advantageously and successively introduced into the μ‐star polymer. In practice, repetition of the reaction sequence affords well‐defined 3‐arm ABC, 5‐arm ABCDE, 7‐arm ABCDEFG, and even 9‐arm ABCDEFGHI μ‐star polymers, composed of polystyrene, polystyrenes substituted with functional groups, polyisoprene, and poly(alkyl methacrylate) arms, respectively.
Multi‐shape‐memory polymers (MSMPs) are a novel kind of shape‐memory polymer that can fix two or more temporary shapes and recover from the first temporary shape to the other temporary shapes one by one, and finally to a permanent shape. The key factor to realize multi‐shape‐memory effects (MSMEs) is the integration of two or more reversible phases into a polymer network, which is extremely challenging work. Here, a novel strategy is used to achieve MSMEs with just one reversible phase. The polymer networks are prepared based on poly(ε‐caprolactone) (PCL) and ethyl cellulose (EC); two graft polymers with different lengths of PCL chains are combined to prepare MSMPs by three methods. All of them exhibit well triple‐shape‐memory effects and that of direct mixing of EC‐PCL even shows quadruple‐shape‐memory effects. Moreover, the effects of the thermomechanical conditions on the MSMEs are also investigated and the results demonstrate that the programming conditions have a great impact.
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