Abstract: A high-grafting density cyclic comb shaped polymer and its preparation method therefor. The method comprises the following steps: 1) synthesizing linear poly(pentafluorophenyl 4-vinylbenzoate) (l-PPF4VB4.0k); 2) performing photo-induced cyclization on the linear polymer to prepare the cyclic polymer (c-PPF4VB4.0k); 3) performing post modification on the cyclic polymer c-PPF4VB4.0k by using small molecules to prepare a functionalized cyclic polymer (c-P1); 4) then performing polymer post modification on the cyclic polymer (c-P1) by using an efficient click reaction to construct the high-grafting density cyclic comb shaped polymer (c-P1-g-PS); and 5) directly performing polymer post modification on the cyclic polymer c-PPF4VB4.0k by using macromolecules to construct a high-grafting density cyclic comb shaped polymer (c-PPF4VB4.0k-g-PEG), the obtained cyclic comb shaped polymer still remaining the characteristic of a narrow molecular weight distribution.

Abstract: The present disclosure relates to an additive used in a methionine preparation process, and a methionine preparation method. The additive provided by the present disclosure is a mixture containing components A, B, and C; component A has a structure represented by the following general formula (1); component B has a structure represented by the following general formula (2); component C is silicone oil; RCON(CH3)CH2CH2SO3Na (1). The methionine preparation method provided in the present invention comprises subjecting methionine to crystallization and/or recrystallization in the presence of the additive provided by the present disclosure. The additive provided by the present disclosure results in uniform emulsification, has good stability, can be used stably for a long time, and is suitable for a continuous crystallization process. The prepared methionine crystal has a good crystal form, a large bulk density, and good flowability.

Abstract: The present disclosure relates to a dense boron nitride ceramic with high plasticity and high elasticity and the preparation process thereof. The preparation process includes the following steps: A) weighing a predetermined amount of spherical boron nitride nano-powders with onion-like structure, pre-pressing them into a pre-pressed body and putting the pre-pressed body into a sintering mold; B) putting the pre-pressed body obtained in step A) together with the sintering mold into a spark plasma sintering apparatus or a hot-pressing sintering apparatus for sintering; and C) taking out the mold after cooling, and removing the mold to obtain the boron nitride dense ceramic block with high plasticity and high elasticity. According to the present invention, a boron nitride ceramic with high strength and high plasticity is obtained via sintering spherical boron nitride nano-powders with onion-like structure.

Abstract: A high-grafting density cyclic comb shaped polymer and its preparation method therefor. The method comprises the following steps: 1) synthesizing linear poly(pentafluorophenyl 4-vinylbenzoate) (l-PPF4VB4.0k); 2) performing photo-induced cyclization on the linear polymer to prepare the cyclic polymer (c-PPF4VB4.0k); 3) performing post modification on the cyclic polymer c-PPF4VB4.0k by using small molecules to prepare a functionalized cyclic polymer (c-P1); 4) then performing polymer post modification on the cyclic polymer (c-P1) by using an efficient click reaction to construct the high-grafting density cyclic comb shaped polymer (c-P1-g-PS); and 5) directly performing polymer post modification on the cyclic polymer c-PPF4VB4.0k by using macromolecules to construct a high-grafting density cyclic comb shaped polymer (c-PPF4VB4.0k-g-PEG), the obtained cyclic comb shaped polymer still remaining the characteristic of a narrow molecular weight distribution.

Abstract: The present disclosure relates to a dense boron nitride ceramic with high plasticity and high elasticity and the preparation process thereof. The preparation process includes the following steps: A) weighing a predetermined amount of spherical boron nitride nano-powders with onion-like structure, pre-pressing them into a pre-pressed body and putting the pre-pressed body into a sintering mold; B) putting the pre-pressed body obtained in step A) together with the sintering mold into a spark plasma sintering apparatus or a hot-pressing sintering apparatus for sintering; and C) taking out the mold after cooling, and removing the mold to obtain the boron nitride dense ceramic block with high plasticity and high elasticity. According to the present invention, a boron nitride ceramic with high strength and high plasticity is obtained via sintering spherical boron nitride nano-powders with onion-like structure.