Copolymer Research Articles

Effect of Phosphoric Acid on Corrosion Performance of Vinyl Chloride-acrylic Copolymer Coating on Rust Steel

Effect of Phosphoric Acid on Corrosion Performance of Vinyl Chloride-acrylic Copolymer Coating on Rust Steel

Study on unsaturated structure and tacticity of poly1-hexene and new copolymer of 1-hexene/5-hexene-1-ol prepared by metallocene catalyst

1-hexene homopolymerization and 1-hexene/5-hexene-1-ol copolymerization were conducted using metallocene, Cp2ZrCl2, catalyst with methylaluminoxane (MAO) as activating agent. IR and 13C NMR analyses of the resulting (co)polymers was done to confirm incorporation of functional monomer to the poly1-hexene backbone.13C-and 1H NMR analyses were carried out to identify the tacticity and termination reaction mechanisms of (co)polymerization and study unsaturated structures of the (co)polymers. Our results showed that this catalytic system produces homopolymer chains with, vinylidene (CH2=CRR′, Vd, resulted from 1,2-inserted chain-end) end structure and with 74% isotacticity; while that in the copolymer both Vd (resulted from 1,2-inserted mechanism, 70%) and di-substituted vinylene (2Vn, resulted from 2,1-inserted mechanism, 30%) chain ends have been seen.

Прищеплені кополімери ПВС-g-ПАА як ефективні матриці для формування і стабілізації наночастинок срібла

Прищеплені кополімери ПВС-g-ПАА як ефективні матриці для формування і стабілізації наночастинок срібла

External Cross-linked Mucoadhesive Microbeads for Prolonged Drug Release: Development and In vitro Characterization.

Mucoadhesive microbeads of low methoxyl pectin were prepared, either alone or in combinations with hydroxypropyl methyl cellulose, sodium carboxymethyl cellulose, methyl cellulose and carbopol 934P, by ionotropic gelation. The influence of copolymers on mucoadhesivity, microbeads characteristics and in vitro drug release was investigated. Spherical microbeads with 78.69±0.59 to 85.84±0.78% drug entrapment and of a size of 791.90±4.58 to 960.88±4.61 μm were prepared. The concentration of cross linking agent affects the encapsulation efficiency of microbeads. Mucoadhesiveness of microbeads was dependent on the concentration of copolymers. The formulations exhibiteda pH-dependent release and followed diffusion-controlled first-order kinetics.

PET-RAFT + ROP = Copolymers!

Key words chain transfer polymerization - ring-opening polymerization - copolymers - radical polymerization

Experimental research about the copolymers of DR-PLGA microcapsule and CPC on the treatment of rabbit femoral defect model

Objective To study the effects about rhizoma drynariae poly(lactic-co-glycolic acid) (DR-PLGA) /Calcium phosphate cement (CPC) composite scaffold on treating rabbit femoral bone defect. Methods Eight Newzealand rabbits were randomly divided into experiment group(n=4) and control group (n=4). The preparation of rabbit femoral bone defect model, separately implanted DR-PLGA/CPC scaffold and PLGA/CPC scaffold. After 4, 8 weeks, we took out the materials, observed with X-ray, gross anatomy, histology observation to evaluate the osteogenetic activity, the effect of accelerating the healing of bone defect. Resuits At the 4th week and 8th week after implantation, the effect of promoting fracture healing and osteogenic activity of the experiment group were greater than those in the control group. Conclusions DR-PLGA combined with CPC could induce new bone formation, promote the healing of rabbit femoral defect. Key words: Polypodiacease; Rhizoma-drynariae/poly, lactic-co-glycolide facid; Calcium phosphate cement; Rabbits; Treatment outcome

Approach to Rapid Synthesis and Functionalization of Iron Oxide Nanoparticles for High Gene Transfection

Surface functionalization of theranostic nanoparticles (NPs) typically relies on lengthy, aqueous postsynthesis labeling chemistries that have limited ability to fine-tune surface properties and can lead to NP heterogeneity. The need for a rapid, simple synthesis approach that can provide great control over the display of functional moieties on NP surfaces has led to increased use of highly selective bioorthoganol chemistries including metal-affinity coordination. Here we report a simple approach for rapid production of a superparamagnetic iron oxide NPs (SPIONs) with tunable functionality and high reproducibility under aqueous conditions. We utilize the high affinity complex formed between catechol and Fe((III)) as a means to dock well-defined catechol modified polymer modules on the surface of SPIONs during sonochemical coprecipitation synthesis. Polymer modules consisted of chitosan and poly(ethylene glycol) (PEG) copolymer (CP) modified with catechol (CCP), and CCP functionalized with cationic polyethylenimine (CCP-PEI) to facilitate binding and delivery of DNA for gene therapy. This rapid synthesis/functionalization approach provided excellent control over the extent of PEI labeling, improved SPION magnetic resonance imaging (MRI) contrast enhancement and produced an efficient transfection agent.

Preparation and Characterization of Chitosan Oligo-Saccharide-Hydrolyzed Gliadin Copolymer

Preparation and Characterization of Chitosan Oligo-Saccharide-Hydrolyzed Gliadin Copolymer

NEW SYNTHESIZED METALS CHELATING TERPOLYMER RESIN (O-AABF)

Anew chelating terpolymer resin (o-AABF) was synthesized through the copolymerization of o-Amino acetophenone, Biuret, Formaldehyde in (1:1:3) mol ratio in acidic medium (HCl) by condensation reaction. The synthesized copolymer resin was characterized by UV-Visible, FTIR and 1 HNMR techniques. The empirical structure and molecular weight of the resin were analyzed by elemental analysis. Morphological structure of the synthesized resin was studied by scanning electron microscopy (SEM). Thermal properties and stability of the resin was determined by DSC and TGA instruments. The intrinsic viscosity and the viscosity average molecular weight were calculated. Selectivity and binding capacity of the terpolymer resin studied by Batch equilibrium method toward certain trivalent and divalent metal ions Ni +2 , Co +2 , Cd +2 , Cu +2 , Zn +2 and Cr +3 in different pH and treatment time.

Theoretical insights into the CO dimerization and trimerization on Pt nanocluster

CO dimerizaiton and trimerization on icosahedral Pt55 cluster.

Fabrication of polycarboxylate/graphene oxide nanosheet composites using copolymerization, for reinforcing and toughening cement composites

Fabrication of polycarboxylate/graphene oxide nanosheet composites using copolymerization, for reinforcing and toughening cement composites

Studies on the Synthesis, Micellization and Gelation of Novel Temperature- and pH-Sensitive ABA Triblock Copolymers

采用原子转移自由基聚合（ATRP）方法合成了水溶性良好的不同聚合度的三嵌段共聚物P（DEAEMA-co-MEO，MA-co-HMAM）-b-PEG-b-P（DEAEMA-CO-MEO2MA-co-HMAM）．利用傅里叶变换红外光谱（FT-IR）、核磁共振氢谱（1HNMR）以及凝胶渗透色谱（GPC）对聚合物结构及组成进行表征；通过透光率、表面张力的测定以及动态光散射（DLS）、荧光探针和透射电镜（TEM）技术研究了共聚物水溶液的性质及胶束化行为．通过对不同pH下共聚物的凝胶状态和不同pH下温度诱导的溶胶-凝胶转变过程的观察，研究了温度和pH对共聚物凝胶化行为的影响．测定了载药凝胶分别在不同温度和不同pH的缓冲溶液中对药物的累积释放率．结果表明：ABA型三嵌段共聚物具有良好的温敏性和pH敏感性，在温度或pH诱导下可形成核壳胶束和凝胶．载药凝胶对药物的累积释放率随温度和pH的降低而升高．

Visual detection of Al3+ ions using conjugated copolymer-ATP supramolecular complex

A colorimetric Al3+ sensor based on fluorescence recovery of a conjugated copolymer-ATP complex is proposed. An optimized ratio of two polythiophene (PT) monomers is utilized to synthesize copolymer (CP) that yielded maximized colorimetric response for Al3+ in deionized (DI) and tap water. The electrostatic disassembly of CP-ATP upon addition of Al3+ led to an evident visual color change. The lowest concentration of Al3+ for naked eye observation is around 4 μM, which is below the threshold levels in drinking water according to European Economic Community (EEC) standard. Besides, the proposed assay showed a similar response to Al3+ in tap water. The proposed methodology showed selective and sensitive detection for Al3+ in analytically relevant concentration ranges without involving sophisticated instrumentation, illustrating the applicability for on-site drinking water monitoring.

Synthesis and characterization of a novel amphiphilic block copolymer as a potential drug carrier

This paper presents the synthesis procedure of a novel amphiphilic block-copolymer poly(ethylene glycol)-b-poly(lactic acid) (PEG-b-PLA) and its various characterization techniques in order to explore the applicability of this copolymer as an agent of encapsulation for hydrophobic drugs. The synthesis consists of ring-opening polymerization (ROP) of L-lactide with stannous octoate (Sn(Oct) 2 ) as a catalyst and methoxy poly(ethylene glycol) mPEG as an initiator. The copolymer is characterized and confirmed by 1 H-NMR spectroscopy, Gel Permeation Chromatography (GPC), and Fourier Transform Infrared spectroscopy (FT-IR). The thermal properties of the synthesized copolymer are determined by Differential Scanning Calorimeter (DSC). The nanoscale size (100-130 nm) and its distribution is verified by Dynamic Light Scattering (DLS) and the critical micelle concentration (CMC) is determined by fluorescence spectrophotometry. The UV measurements show that the polymer has a high encapsulation efficiency (72%) and is able to enhance (28 times) the solubility of a hydrophobic drug, namely Ibuprofen, in an aqueous medium. The results of this study reveal that the novel copolymer could be a potential candidate for hydrophobic drug delivery systems.

聚（ε-己内酯-L-丙交酯）无规共聚物与聚乳酸共混材料的制备与性能

通过开环聚合,合成不同比例的e-己内酯（e-CL）与L-丙交酯（L-LA）的无规共聚物P（CL/LLA）。将上述共聚物P（CL/LLA）与聚乳酸（PLLA）共混,制备了PLA/P（CL/LLA）共混材料。并对其相容性、热性能、力学性能进行了研究。结果表明,共聚物P（CL/LLA）与PLA相容性与共聚物中LA单元含量和链段的平均长度有密切关系,P（CL/LLA）中LA链段平均长度达到3.4以上时,可以与PLA很好的相互作用。同时共聚物P（CL/LLA）中—CL—链段有很好的柔性,可以很好的改善PLLA的韧性,使PLLA材料的断裂伸长率达到500%以上。

Phase Diagram and Transformations of Iron Pentacarbonyl to nm Layered Hematite and Carbon-Oxygen Polymer under Pressure.

We present the phase diagram of Fe(CO)5, consisting of three molecular polymorphs (phase I, II and III) and an extended polymeric phase that can be recovered at ambient condition. The phase diagram indicates a limited stability of Fe(CO)5 within a pressure-temperature dome formed below the liquid- phase II- polymer triple point at 4.2 GPa and 580 K. The limited stability, in turn, signifies the temperature-induced weakening of Fe-CO back bonds, which eventually leads to the dissociation of Fe-CO at the onset of the polymerization of CO. The recovered polymer is a composite of novel nm-lamellar layers of crystalline hematite Fe2O3 and amorphous carbon-oxygen polymers. These results, therefore, demonstrate the synthesis of carbon-oxygen polymer by compressing Fe(CO)5, which advocates a novel synthetic route to develop atomistic composite materials by compressing organometallic compounds.

Synthesis and Characterization of Fluorinated Polybenzoxazole Copolymers

Synthesis and Characterization of Fluorinated Polybenzoxazole Copolymers

Синтез и молекулярные характеристики <i>N</i>-оксидированного сополимера <i>N</i>-винилпирролидона и 2-метил-5-винилпиридина

Окислением сополимеров N-винилпирролидона и 2-метил-5-винилпиридина надуксусной кислотой получены N-оксиды сополимеров с различной степенью N-оксидирования. Методом УФ-спектрофотометрии исследована кинетика N-оксидирования, рассчитаны константы скорости и определена зависимость предельной степени N-оксидирования от температуры процесса. Молекулярные характеристики N-оксидированных сополимеров установлены методом 13С ЯМР. Для практического контроля полноты протекания реакции предложен подход на основе прямой УФ-спектрофотометрии.

Selenophene as a Bridge in Molecular Architecture of Benzotriazole Containing Conjugated Copolymers to Gain Insight on Optical and Electrochemical Properties of Polymers

GRAPHICAL ABSTRACT

Syntheses and Electronic Properties of New Type of Donor–Acceptor Type Copolymers for Solar Cell Applications

GRAPHICAL ABSTRACT