Preparation Of Hyperbranched Polymer And Its Application In PDMS Microfluidic Chips

In this paper, hyperbranched polyaminoester (HPAE) consisted of multitude end hydroxy (-OH) groups was synthesized and its three-dimensional molecule structure was charactered. The HPAE served as modified material for PDMS microchips modified. The modified PDMS microchips were made with physical method and chemical method. The EOF, sepration efficiency of proteins and stability of the coated modified were evaluated, and the results were satisfactory.Particular contents in this paper were summarized as follows:(1) Preparation of HPAE and characterized: The G2, G3 and G4 of HPAE were synthesised via a intiator of polymerization of p-toluenesulfonic acid using trimethylol propane as core molecule and N,N-dihydroxyethyl-3-aminomethyl propionates as monomer. At the same time, a series of HPAE with different degree of branching (DB) were synthesized using one-step procedure by changing the molar ratio of the initiator boron trifluoride ether complex and the monomer N, N-dihydroxyethyl-3-aminomethyl propionates. The characteristic functional groups of the HPAE were characterized by IR. The hydroxyl content was tested by hydroxyl value. The content of C&H were determined by element analysis. The rheological behavior of the the HPAE was investigated using a viscometer. The thermal property has been also estimated by TG-DTA.(2) Modification of PDMS: HPAE was introduced for surface modification of PDMS. The modification of PDMS based microfluidic channels starts from the solution-phase oxidation reaction of PDMS surfaces. And then, the treated PDMS was modified with physical method and chemical method. The characteristic of modified PDMS was characterized tough contact angels measured and surface characteristics.(3) Preparation and evaluation of physical modified PDMS chips: G2, G3 and G4 HPAE modified PDMS chips were fabricated. The HPAE layer can reduce the electroosmotic flow greatly and suppress protein adsorption on the channel surface of PDMS chips effectively. The coated chips provided clean separations of the basic protein at pH=4.5 with phosphate buffer and the separation characteristics of the reproducbility, stability, longevity and separation efficiency were satisfactory. The separation efficiency and resolution (Rs) was gradually improved with the generation of HPAE.(4) Preparation and evaluation of chemical modified PDMS chips: The chemical modified chips were fabricated with G2, G3 and G4 HPAE. Different generations HPAE were coated on the channels of the PDMS chips by silane coupling agentγ-GPTMS using BF3·OEt2 as initiator. The chemical-bonded coated laye also can reduce the electroosmotic flow greatly, suppress protein adsorption on the channel surface of PDMS chips effectively, and provide clean separations of the basic protein at pH=4.5 with phosphate buffer. The separation efficiency and resolution (Rs) was gradually improved with the generation of HPAE.(5) The physical coated chip with HPAE proven to be successful by meeting the simple preparation step, high efficiency, low cost and good stability. All of these merits warrant that this method is superior to many other coatings. Therefore, it has broader application area and generalizable worth.