Abstract: A positive electrode active material for a secondary battery includes a lithium composite transition metal oxide including nickel (Ni), cobalt (Co), and manganese (Mn), wherein the lithium composite transition metal oxide has a layered crystal structure of space group R3m, includes the nickel (Ni) in an amount of 60 mol % or less based on a total amount of transition metals, includes the cobalt (Co) in an amount greater than an amount of the manganese (Mn), and is composed of single particles.

Abstract: A positive electrode active material precursor having a uniform particle size distribution and represented by Formula 1, wherein a percentage of fine powder with an average particle diameter (D50) of 1 ?m or less is generated when the positive electrode active material precursor is rolled at 2.5 kgf/cm2 is less than 1%, and an aspect ratio is 0.93 or more, and a method of preparing the positive electrode active material precursor [NixCoyM1zM2w](OH)2 ??[Formula 1] in Formula 1, 0.5?x<1, 0<y?0.5, 0<z?0.5, and 0?w?0.1, M1 includes at least one selected from the group consisting of Mn and Al, and M2 includes at least one selected from the group consisting of Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, and Y. A method of preparing the positive electrode active material precursor is also provided.

Abstract: The present invention relates to a polyethylene glycol derivative and a preparation method thereof. A preparation process of a polyethylene glycol derivative, according to the present invention, may provide a novel polyethylene glycol derivative which can be utilized in various ways as a drug linker, and is appropriate and effective for mass production and is advantageous in reproducible mass production of high-quality products.

Abstract: The present invention relates to an improved method for preparing a high purity polyethylene glycol dialdehyde derivative. The preparation method can provide the polyethylene glycol dialdehyde derivative suitable as a raw material for pharmaceuticals because of high purity and terminal activity, by using PEG-diacetal, which is prepared by reacting polyethyleneglycol methanesulfonate with dialkoxy-1-propanol, as an intermediate.

Abstract: The present invention relates to a polyethylene glycol derivative and a preparation method thereof. A preparation process of a polyethylene glycol derivative, according to the present invention, may provide a novel polyethylene glycol derivative which can be utilized in various ways as a drug linker, and is appropriate and effective for mass production and is advantageous in reproducible mass production of high-quality products.

Abstract: The present invention relates to an improved method for preparing a high purity polyethylene glycol dialdehyde derivative. The preparation method can provide the polyethylene glycol dialdehyde derivative suitable as a raw material for pharmaceuticals because of high purity and terminal activity, by using PEG-diacetal, which is prepared by reacting polyethyleneglycol methanesulfonate with dialkoxy-1-propanol, as an intermediate.