Previously we found that covalent attachment of long-chained, moderately hydrophobic polycations to surfaces of solid objects renders the latter permanently bactericidal. Herein we replaced such surface-specific, multistep immobilization techniques with a single-step, general procedure akin to common painting. Glass or polyethylene slides were briefly dipped into organic solutions of certain optimally hydrophobic N-alkyl-PEI (where PEI stands for branched 750-kDa polyethylenimine) polycations, followed by solvent evaporation. The resultant polycation-coated slides were able to kill on contact all of the encountered bacterial cells, whether the Gram-positive human pathogen Staphylococcus aureus or its Gram-negative brethren Escherichia coli. This biocidal effect was found not to be caused by N-alkyl-PEI molecules leached from the surface. Further examination of the mechanism of this bactericidal action suggested that the surface-deposited N-alkyl-PEI kills bacteria by rupturing their cellular membranes. This conclusion was further supported by studies in which the molecular weight of PEI and the hydrophobicity of the alkyl moiety were varied.

One-step, painting-like coating procedures to make surfaces highly and permanently bactericidal.

This review summarizes the main advances published over the last 15 years outlining the different methods of grafting, including reactive extruder systems, surface modification, grafting and graft copolymerization of synthetic and natural polymers with maleic anhydride and its isostructural analogues such as maleimides and maleates, and anhydrides, esters and imides of citraconic and itaconic acids, derivatives of fumaric acid, etc. Special attention is spared to the grafting of conventional and non&conventional synth etic and natural polymers, including biodegradable polymers, mechanism of grafting and graft copolymerization, in situ grafting reactions in melt by reactive extrusion systems, in solutions and solid state (photo& and plasma& induced graftings), and H&bonding effect in the rea ctive blend processing. The structural phenomena, unique properties and application areas of these copolymers and their various modifications and composites as high performance engineering materials have been also described.

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Graft Copolymers of Maleic Anhydride and its Isostructural Analogues: High Performance Engineering Materials

Modification of deproteinized natural rubber via grafting polymerization with maleic anhydride

Grafting of maleic anhydride (MA) onto natural rubber (NR) has been investigated by using a radical initiated grafting process. NR was masticated to lower molecular weight than the original NR before treatment with 0.5-1.5% by mole of benzoyl peroxide (BPO) and 5-25% by mole of MA in toluene solution. Fourier transform infrared spectroscopy (FTIR) and titration method were used to analyze the fixation of MA on the NR. The reaction temperature was varied from 60 to 80°C. The % grafting of MA was higher at higher temperatures. Compared to the reaction without styrene, the addition of 0.1% by mole of styrene in the grafting process increased % MA grafting up to two times. It is postulated that the styrene may act as a charge transfer complex for the reaction of NR with MA.

Influence of styrene on grafting efficiency of maleic anhydride onto natural rubber

A review of phase structure of SBS modified asphalt: Affecting factors, analytical methods, phase models and improvements

Chemical initiation mechanism of maleic anhydride grafted onto styrene–butadiene–styrene block copolymer

This paper prepare a composite materials based on abandoned-nutshell,which can be used as low density proppant material in hydraulic fracturingThis composite material was prepared by impregnated crushed nutshell in Resol,and then enwrapped by E-44 resinBy INSTRON,TGA and SEM etc,this paper has studied the relationship between the structure and performanceThe experimental results show that: when Resol's mass fraction is 70 percent,the ant-deformation ability of the composite material is biggestMore E44 resin used,the ant-deformation ability of the composite material is bigger and when E-44 resin's content is bigger than 25 percent,its ant-deformation ability is not changedTGA shows that its hot-endurance ability is bigger than beforeSEM shows that after enwrapped,its surface is more lubricity,less aperturesAbsorbability in distilled water is dropped from(3045) percent to(658) percent

The Study of Phenolic Resin/Epoxy Resin Enwrapped and Modified Nutshell Composite Material

The introduction of polar constituents onto hydrophobic polymers containing polybutadiene block is known to result in considerable improvement of the physical chemical properties.The graft site of vinyl monomers onto polybutadiene have been studied widely but still remained obscure.In this paper the graft reaction mechanism of styrene-butadiene-styrene tri-block copolymer (SBS) with maleic anhydride (MAH) initiated by benzoperoxide (BPO) or 2,2′-azo-bis-iso-butyronitrile (AIBN) was studied by means of FTIR and 1H-NMR.The experimental results show that the graft reaction occurs by addition on the CC double band by the AIBN radical while the BPO radical function by removal of an allylic hydrogen atom from SBS and by addition on the CC double band at the same time.Content of CC bond in SBS-g-MAH of different graft ratio was studied to verify the different graft mechanism of BPO and AIBN.BPO is more effective to allylic hydrogen atom than to butadiene CC for the grafting reaction, so when the concentration of BPO increases, more and more allylic carbon atoms were grafted with MAH, the butadiene CC are protected because of steric hindrance, as a result the content of butadiene CC increase lately.For AIBN, the content of butadiene CC decreases as concentration of AIBN increases.The graft efficiency of AIBN is higher than BPO in this system, but one prefer to BPO than AIBN with the elastic property of SBS considered.

Studies on the mechanism of sbs graft maleic anhydride with different initiators

The contact angle of SBS-g-MAH initiat ed by different initiator was studied by dynamic contact angle (DCA) before and af ter anneal. DCA results show that the receding contact angle decreases as the gr aft rate increases. When the sample graft rate increases to 4.783%, the rece ding contact angle reaches 0°. The polar components of SBS-g-MAH initiated by AIBN is higher than that initiated by BPO. .After anneal, the receding contact angle initiated by different initiator both increase. Anneal has more effect on graft sample initiated by AIBN than that initiated by BPO. The surface structure of SBS-g-MAH was studied by attenuated total reflectance (FT-IR-ATR). FT-I R-ATR results show that sample initiated by AIBN has more carbonyl group on the surface than that of BPO. When the sample graft rate reaches 4.783%, carbon yl group dispersed at the surface increases sharply. After anneal, carbonyl grou p on the surface of SBS-g-MAH membrane decreases. Whether or not MAH transferr ing to the surface of membrane accounts for the change of contact angle.

THE STUDY ON SURFACE STRUCTURE OF SBS-g-MAH INITIA TEDBY DIFFERENT INITIATOR BEFORE AND AFTER ANNEAL

In order to prepare waterborne polyurethane(WPU) with better water resistance, the WPU emulsion was synthesized with polyester diol(PBA), toluene diisocyanate(TDI) and 2,2-dimethylol propionic acid (DMPA) as main raw materials. The influences of DMPA content, R value(namely molar ratio of -NCO to -OH) and cross linker were elaborated on water resistance of WPU pliofilm. The experiment results showed that the WPU pliofilm had better water resistance when mass fraction of DMPA was 4% and R value was 1.5. When the mass fraction of aziridine cross linker A was 3% in dry solid content of WPU emulsion, the water absorption of WPU pliofilm modified by different room temperature cross linker could be reduced to about 3%, and the WPU pliofilm had better permanent water resistance.

Zhang Ai-min

Papers

Chemical initiation mechanism of maleic anhydride grafted onto styrene–butadiene–styrene block copolymer

The Study of Phenolic Resin/Epoxy Resin Enwrapped and Modified Nutshell Composite Material

Studies on the mechanism of sbs graft maleic anhydride with different initiators

THE STUDY ON SURFACE STRUCTURE OF SBS-g-MAH INITIA TEDBY DIFFERENT INITIATOR BEFORE AND AFTER ANNEAL

Study on improving water resistance of waterborne polyurethane