東華大學圖書館 |

Language: English

Help

回圖書館首頁

手機版館藏查詢

Back

Switch To: Labeled | MARC Mode | ISBD

Pressure effects on entropically dri...

Lavery, Kristopher A.

Linked to FindBook

Google Book

Amazon

博客來

Pressure effects on entropically driven phase transitions in block copolymers.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Pressure effects on entropically driven phase transitions in block copolymers./
Author:	Lavery, Kristopher A.
Description:	143 p.
Notes:	Source: Dissertation Abstracts International, Volume: 66-11, Section: B, page: 6004.
Contained By:	Dissertation Abstracts International66-11B.
Subject:	Chemistry, Polymer. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3193915
ISBN:	9780542382871

Pressure effects on entropically driven phase transitions in block copolymers.
Lavery, Kristopher A.

Pressure effects on entropically driven phase transitions in block copolymers. - 143 p.

Source: Dissertation Abstracts International, Volume: 66-11, Section: B, page: 6004.

Thesis (Ph.D.)--University of Massachusetts Amherst, 2005.

The binary polymer system of polystyrene and poly(n-pentyl methacrylate) was recently found to exhibit closed-loop type phase behavior. This is the first known example of a weakly interacting system exhibiting such a phase diagram. At atmospheric pressure the block copolymer displays both a lower disorder-to-order and upper-order-to-disorder transition, representing the lower and upper bounds of the closed-loop phase diagram. The application of hydrostatic pressure served to shrink the closed-loop, yielding pressure coefficients of the lower disorder-to-order and upper order-to-disorder transitions of 725°C/kbar and -725°C/kbar respectively. These pressure coefficients were consistent with those calculated from the Clausius-Clapeyron equation, using the experimentally determined DeltaHdisorder and DeltaV disorder for each transition. The chieff determined from small angle neutron scattering (SANS) was found to decrease, pass through a minimum, increase to a maximum, and then decrease with increasing temperature. Swelling the system with carbon dioxide served to promote an expansion of the closed-loop. This was due to the entropic nature of both transitions, with differential dilation of the copolymer domains resulting in dissimilar compressibilities of the blocks. In addition to influencing block copolymer phase behavior, carbon dioxide can have a profound impact on resulting morphological structure. A 42/58 PS-b-PnPMA diblock copolymer was found to exhibit lamellar morphology at ambient pressures. With the application of 2500 psi carbon dioxide the morphology shifted to hexagonally-packed cylinders due to preferential absorption into the PnPMA block. Furthermore, the influence of carbon dioxide sorption on the morphology of the PS/poly(n-alkyl methacrylate) block copolymer series was studied both in thin films and in the bulk.

ISBN: 9780542382871Subjects--Topical Terms:

1018428
Chemistry, Polymer.

Pressure effects on entropically driven phase transitions in block copolymers.
LDR:02776nmm 2200277 4500 001 1826672
005 20061218070910.5
008 130610s2005 eng d
020 $a 9780542382871
035 $a (UnM)AAI3193915
035 $a AAI3193915
040 $a UnM $c UnM
100 1 $a Lavery, Kristopher A. $3 1915629
245 1 0 $a Pressure effects on entropically driven phase transitions in block copolymers.
300 $a 143 p.
500 $a Source: Dissertation Abstracts International, Volume: 66-11, Section: B, page: 6004.
500 $a Director: Thomas P. Russell.
502 $a Thesis (Ph.D.)--University of Massachusetts Amherst, 2005.
520 $a The binary polymer system of polystyrene and poly(n-pentyl methacrylate) was recently found to exhibit closed-loop type phase behavior. This is the first known example of a weakly interacting system exhibiting such a phase diagram. At atmospheric pressure the block copolymer displays both a lower disorder-to-order and upper-order-to-disorder transition, representing the lower and upper bounds of the closed-loop phase diagram. The application of hydrostatic pressure served to shrink the closed-loop, yielding pressure coefficients of the lower disorder-to-order and upper order-to-disorder transitions of 725°C/kbar and -725°C/kbar respectively. These pressure coefficients were consistent with those calculated from the Clausius-Clapeyron equation, using the experimentally determined DeltaHdisorder and DeltaV disorder for each transition. The chieff determined from small angle neutron scattering (SANS) was found to decrease, pass through a minimum, increase to a maximum, and then decrease with increasing temperature. Swelling the system with carbon dioxide served to promote an expansion of the closed-loop. This was due to the entropic nature of both transitions, with differential dilation of the copolymer domains resulting in dissimilar compressibilities of the blocks. In addition to influencing block copolymer phase behavior, carbon dioxide can have a profound impact on resulting morphological structure. A 42/58 PS-b-PnPMA diblock copolymer was found to exhibit lamellar morphology at ambient pressures. With the application of 2500 psi carbon dioxide the morphology shifted to hexagonally-packed cylinders due to preferential absorption into the PnPMA block. Furthermore, the influence of carbon dioxide sorption on the morphology of the PS/poly(n-alkyl methacrylate) block copolymer series was studied both in thin films and in the bulk.
590 $a School code: 0118.
650 4 $a Chemistry, Polymer. $3 1018428
650 4 $a Engineering, Materials Science. $3 1017759
690 $a 0495
690 $a 0794
710 2 0 $a University of Massachusetts Amherst. $3 1019433
773 0 $t Dissertation Abstracts International $g 66-11B.
790 1 0 $a Russell, Thomas P., $e advisor
790 $a 0118
791 $a Ph.D.
792 $a 2005
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3193915