The present invention relates to the technical field of well drilling, and discloses a plugging agent for temperature-resistant calcium-resistant water-based drilling fluid used in oil and gas reservoir protection, a drilling fluid, and uses of the plugging agent and the drilling fluid. The plugging agent for temperature-resistant calcium-resistant water-based drilling fluid used in oil and gas reservoir protection contains acrylamide-diallyldimethylammonium chloride copolymer modified graphene, wherein in the acrylamide-diallyldimethylammonium chloride copolymer, a molar ratio of structural units provided by acrylamide to structural units provided by diallyldimethylammonium chloride is 1:5-15, and the number-average molecular weight of the acrylamide-diallyldimethylammonium chloride copolymer is 15,000-30,000. The water-based drilling fluid described in the present invention is especially applicable to well drilling in deep salt-gypsum formations, and can exhibit good filtrate reducing, plugging, temperature-resistant, anti-collapsing, and reservoir protection performance.

Provided are an organic rare-earth solid micelle, a preparation method therefor, and a method for increasing the photoelectric conversion efficiency of a solar battery. A small organic conjugated ligand is taken as a first ligand, an amphiphilic diblock polymer is taken as a second ligand, and the first ligand and the second ligand are mixed and doped with a rare-earth chloride solution, and self-assembled to form an organic rare-earth solid micelle, whereby the fluorescence emission intensity and the fluorescence efficiency of the rare-earth element are improved. Next, the prepared organic rare-earth solid micelle is spin coated on an ITO layer of a solar battery, to prepare a solar battery with the organic rare-earth solid micelle. Therefore the sunlight absorption of a cell is increased, and the photoelectric conversion efficiency is improved. The preparation process is simple, low in cost, high in photoelectric conversion efficiency, and environmentally friendly.

The present invention relates to a modified conjugated diene-based polymer having a high modification ratio with improved compounding properties by being excellent affinity with a filler and a method for preparing the same. The modified conjugated diene-based polymer thus prepared includes a functional group derived from a compound represented by Formula 1 at one terminal, and has excellent affinity with a filler. If the modified conjugated diene-based polymer is applied to a rubber composition, excellent processability, tensile strength and viscoelasticity may be achieved.

A biodegradable and substantially water-soluble thermoplastic polyvinyl alcohol-based diverting agent is provided which comprises pellets of a specified polyvinyl alcohol optionally with certain specified additives, which pellets are made in an extruder and cut to a specified size.

Provided are particulate polyvinyl alcohol-based loss circulation control compositions for use in subterranean treatments, which are prepared by compacting a specified polyvinyl alcohol copolymer with an acid-soluble weighting agent, optionally with other specified additives and other polyvinyl alcohols.

Provided are low dust-content particulate polyvinyl alcohol-based compositions suitable for a variety of end uses including for use in subterranean treatments and for manufacturing chemical materials, which are prepared by compacting a specified polyvinyl alcohol polymer resins, optionally with specified additives and/or other polyvinyl alcohols.

Polar modifier systems based on a blend of DTHFP, ETE, TMEDA, DMTHFMA and/or functionally similar compounds with BDMAEE and SMT are used to make block copolymers having high levels of pendant vinyl double bond repeat units, which is through highly selective 1,2-bond butadiene addition, low vinylcyclopentane formation, unimodal narrow molecular weight distribution, and a low level of randomized co-monomer repeat units. The block copolymers have very high levels of 1,2-vinyl content and high 3,4-vinyl bond addition of the conjugated diene monomer and low vinylcyclopentane content. The polar modifier systems provide a fast polymerization rate, with a unimodal narrow molecular weight distribution. The polar modifier systems allow operation at a higher temperature than in prior art systems, which reduces cooling requirements.

The present invention provides a gel containing a crosslinked polymer having at least one selected from the group consisting of an acidic dissociative group, an acidic dissociative group in a salt form, and a derivative group of an acidic dissociative group, and a condensate of a compound represented by the following formula (I): Si{R.sup.1N(R.sup.2)(R.sup.3)}(OR.sup.4)(OR.sup.5)(R.sup.6) (wherein each group is as defined in the DESCRIPTION).

A modified conjugated diene-based polymer having a weight average molecular weight of 2010.sup.4 or more and 30010.sup.4 or less, and having a molecular weight distribution Mw/Mn of 1.6 or more and 4.0 or less, wherein a modification ratio with respect to a total amount of the conjugated diene-based polymer is 50% by mass or more, a modification ratio of a component having a molecular weight which is of a molecular weight at a peak top, or a peak top of the minimum molecular weight when a plurality of the peak tops of molecular weights is present, in a gel permeation chromatography curve is or more of the modification ratio with respect to the total amount of the conjugated diene-based polymer, and a content of nitrogen contained in the modified conjugated diene-based polymer is 3 mass ppm or more and 70 mass ppm or less.

An aqueous emulsion is made by emulsion polymerizing at least one free-radically polymerizable monomer and one or more di- or higher-functional chain-extending monomers in the presence of an aqueous solution of an oligomer made from a mixture of free-radically polymerizable monomers including acid-functional free-radically polymerizable comonomers, adhesion-promoting free-radically polymerizable comonomers and other free-radically polymerizable comonomers. The aqueous emulsion is substantially free of adipic dihydrazide, has a minimum film forming temperature55 C., and on drying has a Koenig hardness of at least 40 sec.