Synthetic control of molecular weight and microstructure of processible poly(methylsilsesquioxane)s for low-dielectric thin film applications

Lee, Jin-Kyu; Char, Kookheon; Rhee, Hee‐Woo; Ro, Hyun Wook; Yoo, Dae Young; Yoon, Do Young

doi:10.1016/s0032-3861(01)00401-3

Cited by 70 publications

(50 citation statements)

References 20 publications

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“…The properties or microstructures of the polysilsesquioxanes are known to greatly affect the miscibility of dissimilar materials as well as the film properties, as indicated in previous reports. [17,18] In this regard, the CS-PSSQs, which act as the main matrices, are designed to have many functional end-groups such as SiOH or SiOCH 3 in order to enhance their miscibility with other domain forming materials such as PCL, when dielectric thin films are formed. The contents of the functional groups of the CSPSSQs were analyzed by 1 H NMR spectroscopy.…”

Section: Resultsmentioning

confidence: 99%

Nanoporous Low Dielectric Cyclosiloxane Bearing Polysilsesquioxane Thin Films Templated by Poly(ε‐caprolactone)

Hyeon-Lee¹,

Lyu²,

Lee³

et al. 2004

Macro Materials & Eng

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Summary: Dielectric cyclosiloxane bearing polysilsesquioxanes (CS‐PSSQs) were prepared by acid catalyzed polymerization using 2,4,6,8‐tetramethyl‐2,4,6,8‐tetra(trimethoxysilylethyl)cyclotetrasiloxane. The molecular weight, and content of the functional end‐groups of the CS‐PSSQs were found to be dependent on the process parameters, such as the molar ratio of water and catalyst to the OCH3 group of the silane monomer, the amount of solvent, and the poly(ε‐caprolactone) (PCL) content, etc. Based on these CS‐PSSQ prepolymers, nanoporous organic/inorganic hybrid thin films were fabricated by spin‐coating mixtures of these prepolymers with star‐shaped PCL on the silicon substrate, and subsequently heating them at 150 and 250 °C for 1 minute each and then at 420 °C for 1 hour. A dielectric constant as low as 2.28 was achieved for the nanoporous PCL/CS‐PSSQ (3:7 v/v) film, along with low moisture absorption in ambient and water conditions, primarily due to the presence of hydrophobic moieties such as ethylene and methyl groups of the polymer and nano‐sized hydrophobic pores inside the matrix, resulting in the film having stable dielectric properties. Moreover, the PCL/CS‐PSSQ (3:7 v/v) nanohybrid film revealed a nanoporous structure containing ca. 1.52 nm of average‐sized mesopores, as measured by the N2 adsorption method. The CS‐PSSQ‐only film showed high mechanical strengths having an elastic modulus and hardness of 6.64 and 0.88 GPa, respectively, for the 7 500 Å thick film and 2.41 and 0.38 GPa, respectively, for the PCL/CS‐PSSQ (3:7 v/v) film. In addition, the crack velocity of the CS‐PSSQ‐only film was found to be ca. 10−11 m · s−1 in ambient conditions and an aqueous environment, probably due to the enhanced hydrophobicity and mechanical toughness of the incorporated methyl group, siloxane unit and ethylene moieties in the polymer matrix. magnified image

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Section: Resultsmentioning

confidence: 99%

Nanoporous Low Dielectric Cyclosiloxane Bearing Polysilsesquioxane Thin Films Templated by Poly(ε‐caprolactone)

Hyeon-Lee¹,

Lyu²,

Lee³

et al. 2004

Macro Materials & Eng

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“…[1][2][3][4][5][6][7][8][9][10][11][12] The graft polymerization from the silsesquioxane backbone is an effective method for transforming the silsesquioxanes into practical and useful materials. [13][14][15][16][17][18][19][20] Grafted silsesquioxanes are expected to show functions based on the incorporated polymeric components without losing the essential properties of the inorganic polysiloxane structure, such as durability against heat and weatherability.…”

Section: Introductionmentioning

confidence: 99%

Graft polymerization of acrylamide monomers from polysilsesquioxane containing xanthate groups

Kashio

Sugizaki

Miyasaka

et al. 2012

Polym J

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Polysilsesquioxanes (PSQs) containing 4-chloromethylphenyl groups were prepared and used for introducing ethylxanthate groups. The obtained PSQs that contained benzyl xanthate structures (XAPSQs) were employed as macroinitiators for grafting acrylamide monomers. The use of XAPSQs for the radical polymerization with acryloylmorpholine (ACMO), N,Ndimethylacrylamide (DMAA) or N-isopropylacrylamide enabled the preparation of the respective grafted PSQ, in which no cross-linked product was formed. The results of the graft polymerizations from XAPSQs supported the interpretation that the reversible addition-fragmentation chain transfer polymerization progressed effectively using the technique known as macromolecular design via the interchange of xanthate. The introduction of polymerized ACMO and DMAA units provided an amphiphilic property to the grafted PSQ. In addition, the PSQs containing poly(ACMO) components showed reversible hydrophobic aggregation behavior at approximately 801C in aqueous solution. Polymer Journal ( The graft polymerization from the silsesquioxane backbone is an effective method for transforming the silsesquioxanes into practical and useful materials. [13][14][15][16][17][18][19][20] Grafted silsesquioxanes are expected to show functions based on the incorporated polymeric components without losing the essential properties of the inorganic polysiloxane structure, such as durability against heat and weatherability. With the regard to this expectation, we also tried to develop new multifunctional hybrid materials using acrylamide monomers by the graft polymerizations from polysilsesquioxane (PSQ). [21][22][23][24][25][26] In fact, the graftings of polymeric N,N-dimethylacrylamide (DMAA) and N-isopropylacrylamide (NIPAM) successfully produced amphiphilic and thermoresponsive PSQs. 23,24 For the graft polymerizations, the reversible addition-fragmentation chain transfer (RAFT) process was utilized, in which the N,Ndimethyldithiocarbamate (DTC) group was chosen as the chain transfer species. 24 The use of the DTC group was appropriate for designing the sequence and number of monomer units of the graft chains that were the important factors for extending grafted PSQ to a high performance hybrid material. However, in a few examples, the formation of a small amount of by-product that showed unexpectedly high number average molecular weights (M n s) was observed.

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“…In the modification, the properties of the incorporated components are provided to the PSQs in addition to thermal stability and weatherability from the inorganic polysiloxane backbone. [1][2][3][4][5][6][7] Therefore, graft polymerization from or onto PSQ is an effective method to create useful hybrid materials. Consequently, various combinations of polymeric components and PSQs have been investigated.…”

Section: Introductionmentioning

confidence: 99%

“…The possibility of developing a new hybrid led us to attempt the ring-opening polymerization of TMC using 1,5,7-triazabicyclo [4,4,0]-dec-7-ene, which was found to be a metal-free catalyst in our previous grafting of cyclic esters from APSQ. 14 However, in the ring-opening polymerization conducted at 80 1C with furfurylamine as an initiator, the researchers observed the formation of byproducts through decarboxylation.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of grafted polysilsesquioxane by ring-opening polymerization of lactide and trimethylene carbonate

Kashio

Sugizaki

Tanaka

et al. 2011

Polym J

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The polysilsesquioxane (PSQ) containing 3-aminopropyl and phenyl groups (APSQ) was prepared from the corresponding trimethoxysilanes by co-condensation under basic conditions. The amino groups on APSQ were used as the initiator species for the graft polymerization of 1,3-trimethylene carbonate (TMC) and L-(-)-lactide (LA). The ring-opening polymerization of TMC and LA in the presence of the catalytic 1-trimethylsilylimidazole proceeded effectively to afford the PSQ with poly(TMC) and/or poly(LA) as the graft chains. The grafted PSQ containing poly(LA) showed the heat durability as an advantage of the hybrid polymer. In differential scanning calorimetry analysis, the grafted random copolymer of TMC and LA showed no clear endotherm corresponding to melting point (T m ). For the poly(LA)-grafted PSQ, the peak indicating T m was observed in the first heating run, but the corresponding peak was very small in the second run.

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Synthetic control of molecular weight and microstructure of processible poly(methylsilsesquioxane)s for low-dielectric thin film applications

Cited by 70 publications

References 20 publications

Nanoporous Low Dielectric Cyclosiloxane Bearing Polysilsesquioxane Thin Films Templated by Poly(ε‐caprolactone)

Nanoporous Low Dielectric Cyclosiloxane Bearing Polysilsesquioxane Thin Films Templated by Poly(ε‐caprolactone)

Graft polymerization of acrylamide monomers from polysilsesquioxane containing xanthate groups

Synthesis of grafted polysilsesquioxane by ring-opening polymerization of lactide and trimethylene carbonate

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